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draftsjust417(at)gmail.co
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 Posted: Wed Apr 28, 2021 7:59 pm Post subject: Housai engine question: compression check |
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Good evening all-
A conundrum for you Housai engine experts; I need some advice to go fwd.
Doing the compression check today, I hit a weird wall.
With a partner I was checking cylinders starting with #1 at top, going CW when viewed from cockpit.
All #'s were good (avg 75/80 psi), until I got the last cylinder, #2. We got 0 psi on the pressure gauge.
Checking the pressure tester/gauges/fittings/hose, all are fine and perfectly functional.
So we double checked the previous cylinder, which had just 10 min prior tested at 74/80 psi.... now it also
showed 0/80 psi. ??
No obvious air leaks from oil breather, carburetor, or exhaust stack; no oil evident at bases of the cylinders;
the exhaust and intake stacks are good condition. I had flown the plane earlier in the day w/o any negative
indications.
Pulled the valve covers off to find the rocker arms, springs, etc in great condition, doing their job when we
slowly turned the prop thru by hand.
Stuck valves?
We tried the "rope trick" to slip a nylon cord into the cylinder thru the open sparkplug hole, then gently run
the piston up to TDC to try to reseat the possibly stuck-open valves. As yet, no help.
Fishing for advice & thoughts... what are we missing?
I've never seen a 0/80 psi reading... a bad piston ring or bad valve, should have SOME psi indication 30~60psi.
Thoughts? Pointers?
Thanks---
Justin Drafts
N280NC
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threein60
Joined: 04 Feb 2016
Posts: 51
Location: Everett Wa
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| Posted: Wed Apr 28, 2021 8:14 pm Post subject: Housai engine question: compression check |
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Clogged secondary gauge. If you collider off the gauge exist and open the valve between the two gauges, do you get 80/80? If not the second gauge is hosed.
Sent from Yahoo Mail for iPhone
On Wednesday, April 28, 2021, 20:58, Justin Drafts <draftsjust417(at)gmail.com> wrote: | Quote: | Good evening all-
A conundrum for you Housai engine experts; I need some advice to go fwd.
Doing the compression check today, I hit a weird wall.
With a partner I was checking cylinders starting with #1 at top, going CW when viewed from cockpit.
All #'s were good (avg 75/80 psi), until I got the last cylinder, #2. We got 0 psi on the pressure gauge.
Checking the pressure tester/gauges/fittings/hose, all are fine and perfectly functional.
So we double checked the previous cylinder, which had just 10 min prior tested at 74/80 psi.... now it also
showed 0/80 psi. ??
No obvious air leaks from oil breather, carburetor, or exhaust stack; no oil evident at bases of the cylinders;
the exhaust and intake stacks are good condition. I had flown the plane earlier in the day w/o any negative
indications.
Pulled the valve covers off to find the rocker arms, springs, etc in great condition, doing their job when we
slowly turned the prop thru by hand.
Stuck valves?
We tried the "rope trick" to slip a nylon cord into the cylinder thru the open sparkplug hole, then gently run
the piston up to TDC to try to reseat the possibly stuck-open valves. As yet, no help.
Fishing for advice & thoughts... what are we missing?
I've never seen a 0/80 psi reading... a bad piston ring or bad valve, should have SOME psi indication 30~60psi.
Thoughts? Pointers?
Thanks---
Justin Drafts
N280NC
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Looigi
Joined: 20 Apr 2015
Posts: 81
Location: Christchurch, New Zealand
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| Posted: Thu Apr 29, 2021 1:47 am Post subject: Housai engine question: compression check |
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Hi Justin,
I can’t speak for the Housai, but I had the identical thing on my M-14P.
Check your valve clearances. I found mine were a little tight. After adjustment, problem solved.
Failing that, give the top of the valves a whack with a plastic faced hammer to unseat them a few times. This will dislodge any debris that might be holding the valve slightly open.
I hope this helps.
Regards
Chris
draftsjust417(at)gmail.com (draftsjust417(at)gmail.com)> wrote:
Good evening all-
A conundrum for you Housai engine experts; I need some advice to go fwd.
Doing the compression check today, I hit a weird wall.
With a partner I was checking cylinders starting with #1 at top, going CW when viewed from cockpit.
All #'s were good (avg 75/80 psi), until I got the last cylinder, #2. We got 0 psi on the pressure gauge.
Checking the pressure tester/gauges/fittings/hose, all are fine and perfectly functional.
So we double checked the previous cylinder, which had just 10 min prior tested at 74/80 psi.... now it also
showed 0/80 psi. ??
No obvious air leaks from oil breather, carburetor, or exhaust stack; no oil evident at bases of the cylinders;
the exhaust and intake stacks are good condition. I had flown the plane earlier in the day w/o any negative
indications.
Pulled the valve covers off to find the rocker arms, springs, etc in great condition, doing their job when we
slowly turned the prop thru by hand.
Stuck valves?
We tried the "rope trick" to slip a nylon cord into the cylinder thru the open sparkplug hole, then gently run
the piston up to TDC to try to reseat the possibly stuck-open valves. As yet, no help.
Fishing for advice & thoughts... what are we missing?
I've never seen a 0/80 psi reading... a bad piston ring or bad valve, should have SOME psi indication 30~60psi.
Thoughts? Pointers?
Thanks---
Justin Drafts
N280NC
[/quote]
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dsavarese0812(at)bellsout
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| Posted: Thu Apr 29, 2021 3:47 am Post subject: Housai engine question: compression check |
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When you had the valve covers off on #2, did you check the valve lash at TDC? Should be between .25 and .35 mm or .010 - .014.
Dennis
On Thursday, April 29, 2021, 12:01:41 AM EDT, Justin Drafts <draftsjust417(at)gmail.com> wrote:
Good evening all-
A conundrum for you Housai engine experts; I need some advice to go fwd.
Doing the compression check today, I hit a weird wall.
With a partner I was checking cylinders starting with #1 at top, going CW when viewed from cockpit.
All #'s were good (avg 75/80 psi), until I got the last cylinder, #2. We got 0 psi on the pressure gauge.
Checking the pressure tester/gauges/fittings/hose, all are fine and perfectly functional.
So we double checked the previous cylinder, which had just 10 min prior tested at 74/80 psi.... now it also
showed 0/80 psi. ??
No obvious air leaks from oil breather, carburetor, or exhaust stack; no oil evident at bases of the cylinders;
the exhaust and intake stacks are good condition. I had flown the plane earlier in the day w/o any negative
indications.
Pulled the valve covers off to find the rocker arms, springs, etc in great condition, doing their job when we
slowly turned the prop thru by hand.
Stuck valves?
We tried the "rope trick" to slip a nylon cord into the cylinder thru the open sparkplug hole, then gently run
the piston up to TDC to try to reseat the possibly stuck-open valves. As yet, no help.
Fishing for advice & thoughts... what are we missing?
I've never seen a 0/80 psi reading... a bad piston ring or bad valve, should have SOME psi indication 30~60psi.
Thoughts? Pointers?
Thanks---
Justin Drafts
N280NC
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dsavarese0812(at)bellsout
Guest
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| Posted: Thu Apr 29, 2021 4:04 am Post subject: Housai engine question: compression check |
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Also check the the air injector to make sure it is fully closed. It
too
has a very small valve inside of it about the size of a pencil eraser.
If the little valve spring is broken or the valve remains open, it will
of course affect the compression test.
Dennis
A. Dennis Savarese
334-546-8182
www.yak-52.com
On 4/28/2021 11:58 PM, Justin Drafts wrote:
| Quote: | Good evening all-
A conundrum for you Housai engine experts; I need some advice to go fwd.
Doing the compression check today, I hit a weird wall.
With a partner I was checking cylinders starting with #1 at top, going
CW when viewed from cockpit.
All #'s were good (avg 75/80 psi), until I got the last cylinder, #2.
We got 0 psi on the pressure gauge.
Checking the pressure tester/gauges/fittings/hose, all are fine and
perfectly functional.
So we double checked the previous cylinder, which had just 10 min
prior tested at 74/80 psi.... now it also
showed 0/80 psi. ??
No obvious air leaks from oil breather, carburetor, or exhaust stack;
no oil evident at bases of the cylinders;
the exhaust and intake stacks are good condition. I had flown the
plane earlier in the day w/o any negative
indications.
Pulled the valve covers off to find the rocker arms, springs, etc in
great condition, doing their job when we
slowly turned the prop thru by hand.
Stuck valves?
We tried the "rope trick" to slip a nylon cord into the cylinder thru
the open sparkplug hole, then gently run
the piston up to TDC to try to reseat the possibly stuck-open valves.
As yet, no help.
Fishing for advice & thoughts... what are we missing?
I've never seen a 0/80 psi reading... a bad piston ring or bad valve,
should have SOME psi indication 30~60psi.
Thoughts? Pointers?
Thanks---
Justin Drafts
N280NC
|
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bwade154(at)yahoo.com
Guest
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| Posted: Thu Apr 29, 2021 5:48 am Post subject: Housai engine question: compression check |
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Justin on your next compression test start at 1 go to 3, 5, 7, 9, 2, 4, 6, 8, the reason being you only need to move the prop a few deg to be TDC on compression stroke at the next cylinder. Also what kind of air flow do you have with your tester? Valves should be quite evident with the sound of air coming out the exhaust or carb, you don't want to hear it feel it at the breather that's BAD. Maybe take the tester out of the equation and inject air into the cylinder to find the direction of the leak as 0/80 is a very good flow?
On Thursday, April 29, 2021, 12:10:19 AM EDT, Justin Drafts <draftsjust417(at)gmail.com> wrote:
Good evening all-
A conundrum for you Housai engine experts; I need some advice to go fwd.
Doing the compression check today, I hit a weird wall.
With a partner I was checking cylinders starting with #1 at top, going CW when viewed from cockpit.
All #'s were good (avg 75/80 psi), until I got the last cylinder, #2. We got 0 psi on the pressure gauge.
Checking the pressure tester/gauges/fittings/hose, all are fine and perfectly functional.
So we double checked the previous cylinder, which had just 10 min prior tested at 74/80 psi.... now it also
showed 0/80 psi. ??
No obvious air leaks from oil breather, carburetor, or exhaust stack; no oil evident at bases of the cylinders;
the exhaust and intake stacks are good condition. I had flown the plane earlier in the day w/o any negative
indications.
Pulled the valve covers off to find the rocker arms, springs, etc in great condition, doing their job when we
slowly turned the prop thru by hand.
Stuck valves?
We tried the "rope trick" to slip a nylon cord into the cylinder thru the open sparkplug hole, then gently run
the piston up to TDC to try to reseat the possibly stuck-open valves. As yet, no help.
Fishing for advice & thoughts... what are we missing?
I've never seen a 0/80 psi reading... a bad piston ring or bad valve, should have SOME psi indication 30~60psi.
Thoughts? Pointers?
Thanks---
Justin Drafts
N280NC
| | - The Matronics Yak-List Email Forum - | | | Use the List Feature Navigator to browse the many List utilities available such as the Email Subscriptions page, Archive Search & Download, 7-Day Browse, Chat, FAQ, Photoshare, and much more:
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Clouddog
Joined: 02 Jun 2016
Posts: 122
Location: Lebanon, TN
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| Posted: Thu Apr 29, 2021 5:49 am Post subject: Housai engine question: compression check |
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Ok, I may need some help here. It's early, I haven't had my coffee yet and I am but the sharpest knife in the drawer. I saw where you started at the #1 cylinder and went counter clockwise. Then you said you got on the last cylinder (#2) and you started showing problems. The firing order is 1,3,5,7,9,2,4,6,8. In my simple world the last compression check should have been #8. Any chance you are just out of sequence?
Greg "Clouddog" Wrobel
On Thu, Apr 29, 2021, 00:03 Justin Drafts <draftsjust417(at)gmail.com (draftsjust417(at)gmail.com)> wrote:
| Quote: | Good evening all-
A conundrum for you Housai engine experts; I need some advice to go fwd.
Doing the compression check today, I hit a weird wall.
With a partner I was checking cylinders starting with #1 at top, going CW when viewed from cockpit.
All #'s were good (avg 75/80 psi), until I got the last cylinder, #2. We got 0 psi on the pressure gauge.
Checking the pressure tester/gauges/fittings/hose, all are fine and perfectly functional.
So we double checked the previous cylinder, which had just 10 min prior tested at 74/80 psi... now it also
showed 0/80 psi. ??
No obvious air leaks from oil breather, carburetor, or exhaust stack; no oil evident at bases of the cylinders;
the exhaust and intake stacks are good condition. I had flown the plane earlier in the day w/o any negative
indications.
Pulled the valve covers off to find the rocker arms, springs, etc in great condition, doing their job when we
slowly turned the prop thru by hand.
Stuck valves?
We tried the "rope trick" to slip a nylon cord into the cylinder thru the open sparkplug hole, then gently run
the piston up to TDC to try to reseat the possibly stuck-open valves. As yet, no help.
Fishing for advice & thoughts... what are we missing?
I've never seen a 0/80 psi reading... a bad piston ring or bad valve, should have SOME psi indication 30~60psi.
Thoughts? Pointers?
Thanks---
Justin Drafts
N280NC
|
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draftsjust417(at)gmail.co
Guest
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| Posted: Thu Apr 29, 2021 5:55 am Post subject: Housai engine question: compression check |
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Ah, the air injector, good point.That is, the small thimble sized aluminum input line on the top front of each cylinder? (Want to make sure I understand the line you're speaking of.)
I've never had one apart... how are they disassembled & serviced?
Thanks--
Justin
On Thu, Apr 29, 2021, 5:09 AM A. Dennis Savarese <dsavarese0812(at)bellsouth.net (dsavarese0812(at)bellsouth.net)> wrote:
| Quote: | --> Yak-List message posted by: "A. Dennis Savarese" <dsavarese0812(at)bellsouth.net (dsavarese0812(at)bellsouth.net)>
Also check the the air injector to make sure it is fully closed. It
too
has a very small valve inside of it about the size of a pencil eraser.
If the little valve spring is broken or the valve remains open, it will
of course affect the compression test.
Dennis
A. Dennis Savarese
334-546-8182
www.yak-52.com
On 4/28/2021 11:58 PM, Justin Drafts wrote:
> Good evening all-
>
> A conundrum for you Housai engine experts; I need some advice to go fwd.
> Doing the compression check today, I hit a weird wall.
>
> With a partner I was checking cylinders starting with #1 at top, going
> CW when viewed from cockpit.
> All #'s were good (avg 75/80 psi), until I got the last cylinder, #2.
> We got 0 psi on the pressure gauge.
>
> Checking the pressure tester/gauges/fittings/hose, all are fine and
> perfectly functional.
>
> So we double checked the previous cylinder, which had just 10 min
> prior tested at 74/80 psi.... now it also
> showed 0/80 psi. ??
> No obvious air leaks from oil breather, carburetor, or exhaust stack;
> no oil evident at bases of the cylinders;
> the exhaust and intake stacks are good condition. I had flown the
> plane earlier in the day w/o any negative
> indications.
>
> Pulled the valve covers off to find the rocker arms, springs, etc in
> great condition, doing their job when we
> slowly turned the prop thru by hand.
>
> Stuck valves?
>
> We tried the "rope trick" to slip a nylon cord into the cylinder thru
> the open sparkplug hole, then gently run
> the piston up to TDC to try to reseat the possibly stuck-open valves.
> As yet, no help.
>
> Fishing for advice & thoughts... what are we missing?
> I've never seen a 0/80 psi reading... a bad piston ring or bad valve,
> should have SOME psi indication 30~60psi.
>
> Thoughts? Pointers?
> Thanks---
>
> Justin Drafts
> N280NC
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draftsjust417(at)gmail.co
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| Posted: Thu Apr 29, 2021 6:06 am Post subject: Housai engine question: compression check |
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Thanks for all the quick replies folks... going to the hangar in a bit for round 2.
I did try the rubber mallet approach to try and wallop the valves into obedience, no luck but might need to try again.
Mm, I've always had success feeling for the tell-tale puff of air out the open sparkplug hole to indicate the piston was starting it's way up on compression stroke, then finalize the tdc sweet spot (slight prop rotation) under ~40psi.
Once there, raise press to 80psi...
Has always worked well w/ consistent #'s, until yesterday.
With the 0/80 psi reading, esp on a cylinder I'd just checked at 74/80 psi, I lean to Dennis' idea of a stuck-open air input line. ?
But, not sure... I confess I'm a novice on in depth engine issues.
Justin
On Thu, Apr 29, 2021, 6:54 AM Greg Wrobel <clouddog22(at)gmail.com (clouddog22(at)gmail.com)> wrote:
| Quote: | Ok, I may need some help here. It's early, I haven't had my coffee yet and I am but the sharpest knife in the drawer. I saw where you started at the #1 cylinder and went counter clockwise. Then you said you got on the last cylinder (#2) and you started showing problems. The firing order is 1,3,5,7,9,2,4,6,8. In my simple world the last compression check should have been #8. Any chance you are just out of sequence?
Greg "Clouddog" Wrobel
On Thu, Apr 29, 2021, 00:03 Justin Drafts <draftsjust417(at)gmail.com (draftsjust417(at)gmail.com)> wrote:
| Quote: | Good evening all-
A conundrum for you Housai engine experts; I need some advice to go fwd.
Doing the compression check today, I hit a weird wall.
With a partner I was checking cylinders starting with #1 at top, going CW when viewed from cockpit.
All #'s were good (avg 75/80 psi), until I got the last cylinder, #2. We got 0 psi on the pressure gauge.
Checking the pressure tester/gauges/fittings/hose, all are fine and perfectly functional.
So we double checked the previous cylinder, which had just 10 min prior tested at 74/80 psi.... now it also
showed 0/80 psi. ??
No obvious air leaks from oil breather, carburetor, or exhaust stack; no oil evident at bases of the cylinders;
the exhaust and intake stacks are good condition. I had flown the plane earlier in the day w/o any negative
indications.
Pulled the valve covers off to find the rocker arms, springs, etc in great condition, doing their job when we
slowly turned the prop thru by hand.
Stuck valves?
We tried the "rope trick" to slip a nylon cord into the cylinder thru the open sparkplug hole, then gently run
the piston up to TDC to try to reseat the possibly stuck-open valves. As yet, no help.
Fishing for advice & thoughts... what are we missing?
I've never seen a 0/80 psi reading... a bad piston ring or bad valve, should have SOME psi indication 30~60psi.
Thoughts? Pointers?
Thanks---
Justin Drafts
N280NC
|
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pennington.construction.i
Guest
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| Posted: Thu Apr 29, 2021 6:52 am Post subject: Housai engine question: compression check |
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Justin
I can't agree more that Dennis is on top of his radial engine info for sure, he has made my life easier on more than one occasion. The one thing that I haven't seen in the thread is you have confirmed your test equipment didn't die. The reason I ask is you dont hear air anywhere resulting in the very low reading.. Do you get a good compression check on any cylinders at this point.????? Also, based on my education from Dennis, following the firing order for a compression check is preferable.
With the experience you have from the past etc. I would check my compression checker.... Hope you find the issue. Please share with the group once you know.
Mark Pennington
N621CJ
On Thu, Apr 29, 2021 at 10:11 AM Justin Drafts <draftsjust417(at)gmail.com (draftsjust417(at)gmail.com)> wrote:
| Quote: | Thanks for all the quick replies folks... going to the hangar in a bit for round 2.
I did try the rubber mallet approach to try and wallop the valves into obedience, no luck but might need to try again.
Mm, I've always had success feeling for the tell-tale puff of air out the open sparkplug hole to indicate the piston was starting it's way up on compression stroke, then finalize the tdc sweet spot (slight prop rotation) under ~40psi.
Once there, raise press to 80psi...
Has always worked well w/ consistent #'s, until yesterday.
With the 0/80 psi reading, esp on a cylinder I'd just checked at 74/80 psi, I lean to Dennis' idea of a stuck-open air input line. ?
But, not sure... I confess I'm a novice on in depth engine issues.
Justin
On Thu, Apr 29, 2021, 6:54 AM Greg Wrobel <clouddog22(at)gmail.com (clouddog22(at)gmail.com)> wrote:
| Quote: | Ok, I may need some help here. It's early, I haven't had my coffee yet and I am but the sharpest knife in the drawer. I saw where you started at the #1 cylinder and went counter clockwise. Then you said you got on the last cylinder (#2) and you started showing problems. The firing order is 1,3,5,7,9,2,4,6,8. In my simple world the last compression check should have been #8. Any chance you are just out of sequence?
Greg "Clouddog" Wrobel
On Thu, Apr 29, 2021, 00:03 Justin Drafts <draftsjust417(at)gmail.com (draftsjust417(at)gmail.com)> wrote:
| Quote: | Good evening all-
A conundrum for you Housai engine experts; I need some advice to go fwd.
Doing the compression check today, I hit a weird wall.
With a partner I was checking cylinders starting with #1 at top, going CW when viewed from cockpit.
All #'s were good (avg 75/80 psi), until I got the last cylinder, #2. We got 0 psi on the pressure gauge.
Checking the pressure tester/gauges/fittings/hose, all are fine and perfectly functional.
So we double checked the previous cylinder, which had just 10 min prior tested at 74/80 psi.... now it also
showed 0/80 psi. ??
No obvious air leaks from oil breather, carburetor, or exhaust stack; no oil evident at bases of the cylinders;
the exhaust and intake stacks are good condition. I had flown the plane earlier in the day w/o any negative
indications.
Pulled the valve covers off to find the rocker arms, springs, etc in great condition, doing their job when we
slowly turned the prop thru by hand.
Stuck valves?
We tried the "rope trick" to slip a nylon cord into the cylinder thru the open sparkplug hole, then gently run
the piston up to TDC to try to reseat the possibly stuck-open valves. As yet, no help.
Fishing for advice & thoughts... what are we missing?
I've never seen a 0/80 psi reading... a bad piston ring or bad valve, should have SOME psi indication 30~60psi.
Thoughts? Pointers?
Thanks---
Justin Drafts
N280NC
|
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threein60
Joined: 04 Feb 2016
Posts: 51
Location: Everett Wa
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| Posted: Thu Apr 29, 2021 7:05 am Post subject: Housai engine question: compression check |
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I think you have a gauge issue, use another one if you have one. Second connect your gauges to an air source, with the cross bleed valves off and not connect to a cylinder, both gauges should read the same pressure. If that checks, then look for cylinder issues. But what you described, cylinder God than bad doesn’t make sense. Rather points to the test excellent and not the hardware. Let me know what you find. Larry
Sent from Yahoo Mail for iPhone
On Thursday, April 29, 2021, 07:06, Justin Drafts <draftsjust417(at)gmail.com> wrote: | Quote: | Thanks for all the quick replies folks... going to the hangar in a bit for round 2.
I did try the rubber mallet approach to try and wallop the valves into obedience, no luck but might need to try again.
Mm, I've always had success feeling for the tell-tale puff of air out the open sparkplug hole to indicate the piston was starting it's way up on compression stroke, then finalize the tdc sweet spot (slight prop rotation) under ~40psi.
Once there, raise press to 80psi...
Has always worked well w/ consistent #'s, until yesterday.
With the 0/80 psi reading, esp on a cylinder I'd just checked at 74/80 psi, I lean to Dennis' idea of a stuck-open air input line. ?
But, not sure... I confess I'm a novice on in depth engine issues.
Justin
On Thu, Apr 29, 2021, 6:54 AM Greg Wrobel <clouddog22(at)gmail.com (clouddog22(at)gmail.com)> wrote:
| Quote: | Ok, I may need some help here. It's early, I haven't had my coffee yet and I am but the sharpest knife in the drawer. I saw where you started at the #1 cylinder and went counter clockwise. Then you said you got on the last cylinder (#2) and you started showing problems. The firing order is 1,3,5,7,9,2,4,6,8. In my simple world the last compression check should have been #8. Any chance you are just out of sequence?Greg "Clouddog" Wrobel
On Thu, Apr 29, 2021, 00:03 Justin Drafts <draftsjust417(at)gmail.com (draftsjust417(at)gmail.com)> wrote:
| Quote: | Good evening all-
A conundrum for you Housai engine experts; I need some advice to go fwd.
Doing the compression check today, I hit a weird wall.
With a partner I was checking cylinders startingwith #1 at top, going CW when viewed from cockpit.
All #'s were good (avg 75/80 psi), until I got the last cylinder, #2. We got 0 psi on the pressure gauge.
Checking the pressure tester/gauges/fittings/hose, all are fine and perfectly functional.
So we double checked the previous cylinder, which had just 10 min prior tested at 74/80 psi... now it also
showed 0/80 psi. ??
No obvious air leaks from oil breather, carburetor, or exhaust stack; no oil evident at bases of the cylinders;
the exhaust and intake stacks are good condition. I had flown the plane earlier in the day w/o any negative
indications.
Pulled the valve covers off to find the rocker arms, springs, etc in great condition, doing their job when we
slowly turned the prop thru by hand.
Stuck valves?
We tried the "rope trick" to slip a nylon cord into the cylinder thru the open sparkplug hole, then gently run
the piston up to TDC to try to reseat the possibly stuck-open valves. As yet, no help.
Fishing for advice & thoughts.. what are we missing?
I've never seen a 0/80 psi reading... a bad piston ring or bad valve, should have SOME psi indication 30~60psi.
Thoughts? Pointers?
Thanks---
Justin Drafts
N280NC
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draftsjust417(at)gmail.co
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| Posted: Thu Apr 29, 2021 7:25 am Post subject: Housai engine question: compression check |
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YES I'm perpetually grateful for all the expert advice in the group!One day I might advance past Nanchang novice status...
Oh I wish it was my test equipment that had pooped the bed, but it read great for 8 out of 9 cylinders, even going back to randomly check #7 again after #2 and #3 showed that suspicious 0/80 psi reading (even tho 10 min prior, #3 showed a very good 74/80 psi). In a failure of that magnitude, of course the 1st and wisest resort is to question the test equipment, but this time I'm confident, sigh, it's working well.
Will go tap the valves again, and look into the air inlet valves.
Thankfully at first insp, rocker arms, springs, etc still looked factory new.
Good info on the check sequence, thanks all for insights.
Pls keep them coming, and will pass on any new info or solutions I find today...
Justin
On Thu, Apr 29, 2021, 7:57 AM Mark Pennington <pennington.construction.inc.1(at)gmail.com (pennington.construction.inc.1(at)gmail.com)> wrote:
| Quote: | Justin
I can't agree more that Dennis is on top of his radial engine info for sure, he has made my life easier on more than one occasion. The one thing that I haven't seen in the thread is you have confirmed your test equipment didn't die. The reason I ask is you dont hear air anywhere resulting in the very low reading.. Do you get a good compression check on any cylinders at this point.????? Also, based on my education from Dennis, following the firing order for a compression check is preferable.
With the experience you have from the past etc. I would check my compression checker.... Hope you find the issue. Please share with the group once you know.
Mark Pennington
N621CJ
On Thu, Apr 29, 2021 at 10:11 AM Justin Drafts <draftsjust417(at)gmail.com (draftsjust417(at)gmail.com)> wrote:
| Quote: | Thanks for all the quick replies folks... going to the hangar in a bit for round 2.
I did try the rubber mallet approach to try and wallop the valves into obedience, no luck but might need to try again.
Mm, I've always had success feeling for the tell-tale puff of air out the open sparkplug hole to indicate the piston was starting it's way up on compression stroke, then finalize the tdc sweet spot (slight prop rotation) under ~40psi.
Once there, raise press to 80psi...
Has always worked well w/ consistent #'s, until yesterday.
With the 0/80 psi reading, esp on a cylinder I'd just checked at 74/80 psi, I lean to Dennis' idea of a stuck-open air input line. ?
But, not sure... I confess I'm a novice on in depth engine issues.
Justin
On Thu, Apr 29, 2021, 6:54 AM Greg Wrobel <clouddog22(at)gmail.com (clouddog22(at)gmail.com)> wrote:
| Quote: | Ok, I may need some help here. It's early, I haven't had my coffee yet and I am but the sharpest knife in the drawer. I saw where you started at the #1 cylinder and went counter clockwise. Then you said you got on the last cylinder (#2) and you started showing problems. The firing order is 1,3,5,7,9,2,4,6,8. In my simple world the last compression check should have been #8. Any chance you are just out of sequence?
Greg "Clouddog" Wrobel
On Thu, Apr 29, 2021, 00:03 Justin Drafts <draftsjust417(at)gmail.com (draftsjust417(at)gmail.com)> wrote:
| Quote: | Good evening all-
A conundrum for you Housai engine experts; I need some advice to go fwd.
Doing the compression check today, I hit a weird wall.
With a partner I was checking cylinders starting with #1 at top, going CW when viewed from cockpit.
All #'s were good (avg 75/80 psi), until I got the last cylinder, #2. We got 0 psi on the pressure gauge.
Checking the pressure tester/gauges/fittings/hose, all are fine and perfectly functional.
So we double checked the previous cylinder, which had just 10 min prior tested at 74/80 psi.... now it also
showed 0/80 psi. ??
No obvious air leaks from oil breather, carburetor, or exhaust stack; no oil evident at bases of the cylinders;
the exhaust and intake stacks are good condition. I had flown the plane earlier in the day w/o any negative
indications.
Pulled the valve covers off to find the rocker arms, springs, etc in great condition, doing their job when we
slowly turned the prop thru by hand.
Stuck valves?
We tried the "rope trick" to slip a nylon cord into the cylinder thru the open sparkplug hole, then gently run
the piston up to TDC to try to reseat the possibly stuck-open valves. As yet, no help.
Fishing for advice & thoughts... what are we missing?
I've never seen a 0/80 psi reading... a bad piston ring or bad valve, should have SOME psi indication 30~60psi.
Thoughts? Pointers?
Thanks---
Justin Drafts
N280NC
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dsavarese0812(at)bellsout
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| Posted: Thu Apr 29, 2021 7:28 am Post subject: Housai engine question: compression check |
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Try this. Bring the dead cylinder up to TDC. Then without using the compression tester, connect the compressor line directly to the plug adapter you use to do the compression test. If you can adjust the output pressure on the compressor, start at zero and slowly increase the pressure while listening carefully for any air leaks at the dead cylinder. As you increase the pressure from the compressor, if there is an air leak from an exhaust valve, you’ll hear it clearly out of the exhaust stack. If it’s an intake valve, listen at the throat of the carburetor. If it’s an air injector you’ll hear I at the injector’s banjo fitting. Dennis
Sent from my iPhone
| Quote: | On Apr 29, 2021, at 10:08 AM, Justin Drafts <draftsjust417(at)gmail.com> wrote:
Thanks for all the quick replies folks... going to the hangar in a bit for round 2.
I did try the rubber mallet approach to try and wallop the valves into obedience, no luck but might need to try again.
Mm, I've always had success feeling for the tell-tale puff of air out the open sparkplug hole to indicate the piston was starting it's way up on compression stroke, then finalize the tdc sweet spot (slight prop rotation) under ~40psi.
Once there, raise press to 80psi...
Has always worked well w/ consistent #'s, until yesterday.
With the 0/80 psi reading, esp on a cylinder I'd just checked at 74/80 psi, I lean to Dennis' idea of a stuck-open air input line. ?
But, not sure... I confess I'm a novice on in depth engine issues.
Justin
On Thu, Apr 29, 2021, 6:54 AM Greg Wrobel <clouddog22(at)gmail.com (clouddog22(at)gmail.com)> wrote:
| Quote: | Ok, I may need some help here. It's early, I haven't had my coffee yet and I am but the sharpest knife in the drawer. I saw where you started at the #1 cylinder and went counter clockwise. Then you said you got on the last cylinder (#2) and you started showing problems. The firing order is 1,3,5,7,9,2,4,6,8. In my simple world the last compression check should have been #8. Any chance you are just out of sequence?
Greg "Clouddog" Wrobel
On Thu, Apr 29, 2021, 00:03 Justin Drafts <draftsjust417(at)gmail.com (draftsjust417(at)gmail.com)> wrote:
| Quote: | Good evening all-
A conundrum for you Housai engine experts; I need some advice to go fwd.
Doing the compression check today, I hit a weird wall.
With a partner I was checking cylinders starting with #1 at top, going CW when viewed from cockpit.
All #'s were good (avg 75/80 psi), until I got the last cylinder, #2. We got 0 psi on the pressure gauge.
Checking the pressure tester/gauges/fittings/hose, all are fine and perfectly functional.
So we double checked the previous cylinder, which had just 10 min prior tested at 74/80 psi.... now it also
showed 0/80 psi. ??
No obvious air leaks from oil breather, carburetor, or exhaust stack; no oil evident at bases of the cylinders;
the exhaust and intake stacks are good condition. I had flown the plane earlier in the day w/o any negative
indications.
Pulled the valve covers off to find the rocker arms, springs, etc in great condition, doing their job when we
slowly turned the prop thru by hand.
Stuck valves?
We tried the "rope trick" to slip a nylon cord into the cylinder thru the open sparkplug hole, then gently run
the piston up to TDC to try to reseat the possibly stuck-open valves. As yet, no help.
Fishing for advice & thoughts... what are we missing?
I've never seen a 0/80 psi reading... a bad piston ring or bad valve, should have SOME psi indication 30~60psi.
Thoughts? Pointers?
Thanks---
Justin Drafts
N280NC
|
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dsavarese0812(at)bellsout
Guest
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| Posted: Thu Apr 29, 2021 7:33 am Post subject: Housai engine question: compression check |
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Try hitting the rocker arms with the rubber mallet when you have air pressure on the cylinder. It should have a pretty loud “pop” when you strike the rocker arm.
Don’t forget to check the valve lash. This is very important. Especially if a valve is tight.
Dennis
Sent from my iPhone
[quote] On Apr 29, 2021, at 11:28 AM, Anthony Savarese <dsavarese0812(at)bellsouth.net> wrote:
Try this. Bring the dead cylinder up to TDC. Then without using the compression tester, connect the compressor line directly to the plug adapter you use to do the compression test. If you can adjust the output pressure on the compressor, start at zero and slowly increase the pressure while listening carefully for any air leaks at the dead cylinder. As you increase the pressure from the compressor, if there is an air leak from an exhaust valve, you’ll hear it clearly out of the exhaust stack. If it’s an intake valve, listen at the throat of the carburetor. If it’s an air injector you’ll hear I at the injector’s banjo fitting.
Dennis
Sent from my iPhone
>> On Apr 29, 2021, at 10:08 AM, Justin Drafts <draftsjust417(at)gmail.com> wrote:
>>
>
> Thanks for all the quick replies folks... going to the hangar in a bit for round 2.
>
> I did try the rubber mallet approach to try and wallop the valves into obedience, no luck but might need to try again.
>
> Mm, I've always had success feeling for the tell-tale puff of air out the open sparkplug hole to indicate the piston was starting it's way up on compression stroke, then finalize the tdc sweet spot (slight prop rotation) under ~40psi.
> Once there, raise press to 80psi...
> Has always worked well w/ consistent #'s, until yesterday.
>
> With the 0/80 psi reading, esp on a cylinder I'd just checked at 74/80 psi, I lean to Dennis' idea of a stuck-open air input line. ?
> But, not sure... I confess I'm a novice on in depth engine issues.
> Justin
>
>> On Thu, Apr 29, 2021, 6:54 AM Greg Wrobel <clouddog22(at)gmail.com> wrote:
>> Ok, I may need some help here. It's early, I haven't had my coffee yet and I am but the sharpest knife in the drawer. I saw where you started at the #1 cylinder and went counter clockwise. Then you said you got on the last cylinder (#2) and you started showing problems. The firing order is 1,3,5,7,9,2,4,6,8. In my simple world the last compression check should have been #8. Any chance you are just out of sequence?
>>
>> Greg "Clouddog" Wrobel
>>
>>> On Thu, Apr 29, 2021, 00:03 Justin Drafts <draftsjust417(at)gmail.com> wrote:
>>> Good evening all-
>>>
>>> A conundrum for you Housai engine experts; I need some advice to go fwd
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draftsjust417(at)gmail.co
Guest
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| Posted: Thu Apr 29, 2021 7:34 am Post subject: Housai engine question: compression check |
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Excellent, thanks - will def try this. -Justin
On Thu, Apr 29, 2021 at 8:32 AM Anthony Savarese <
dsavarese0812(at)bellsouth.net> wrote:
[quote] Try this. Bring the dead cylinder up to TDC. Then without using the
compression tester, connect the compressor line directly to the plug
adapter you use to do the compression test. If you can adjust the output
pressure on the compressor, start at zero and slowly increase the pressure
while listening carefully for any air leaks at the dead cylinder. As you
increase the pressure from the compressor, if there is an air leak from an
exhaust valve, you’ll hear it clearly out of the exhaust stack. If it’s an
intake valve, listen at the throat of the carburetor. If it’s an air
injector you’ll hear I at the injector’s banjo fitting.
Dennis
Sent from my iPhone
On Apr 29, 2021, at 10:08 AM, Justin Drafts <draftsjust417(at)gmail.com>
wrote:
Thanks for all the quick replies folks... going to the hangar in a bit for
round 2.
I did try the rubber mallet approach to try and wallop the valves into
obedience, no luck but might need to try again.
Mm, I've always had success feeling for the tell-tale puff of air out the
open sparkplug hole to indicate the piston was starting it's way up on
compression stroke, then finalize the tdc sweet spot (slight prop rotation)
under ~40psi.
Once there, raise press to 80psi...
Has always worked well w/ consistent #'s, until yesterday.
With the 0/80 psi reading, esp on a cylinder I'd just checked at 74/80
psi, I *lean* to Dennis' idea of a stuck-open air input line. ?
But, not sure... I confess I'm a novice on in depth engine issues.
Justin
On Thu, Apr 29, 2021, 6:54 AM Greg Wrobel <clouddog22(at)gmail.com> wrote:
> Ok, I may need some help here. It's early, I haven't had my coffee yet
> and I am but the sharpest knife in the drawer. I saw where you started at
> the #1 cylinder and went counter clockwise. Then you said you got on the
> last cylinder (#2) and you started showing problems. The firing order is
> 1,3,5,7,9,2,4,6,8. In my simple world the last compression check should
> have been #8. Any chance you are just out of sequence?
>
> Greg "Clouddog" Wrobel
>
> On Thu, Apr 29, 2021, 00:03 Justin Drafts <draftsjust417(at)gmail.com>
> wrote:
>
>> Good evening all-
>>
>> A conundrum for you Housai engine experts; I need some advice to go fwd
| | - The Matronics Yak-List Email Forum - | | | Use the List Feature Navigator to browse the many List utilities available such as the Email Subscriptions page, Archive Search & Download, 7-Day Browse, Chat, FAQ, Photoshare, and much more:
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draftsjust417(at)gmail.co
Guest
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| Posted: Thu Apr 29, 2021 7:40 am Post subject: Housai engine question: compression check |
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|
More great inputs thanks...
Sorry but pls remind me on best practice to check valve lash?
(Haven't done it since A&P school in 2002.)
On Thu, Apr 29, 2021 at 8:37 AM Anthony Savarese <
dsavarese0812(at)bellsouth.net> wrote:
[quote] Try hitting the rocker arms with the rubber mallet when you have air
pressure on the cylinder. It should have a pretty loud “pop” when you
strike the rocker arm.
Don’t forget to check the valve lash. This is very important. Especially
if a valve is tight.
Dennis
Sent from my iPhone
On Apr 29, 2021, at 11:28 AM, Anthony Savarese <
dsavarese0812(at)bellsouth.net> wrote:
Try this. Bring the dead cylinder up to TDC. Then without using the
compression tester, connect the compressor line directly to the plug
adapter you use to do the compression test. If you can adjust the output
pressure on the compressor, start at zero and slowly increase the pressure
while listening carefully for any air leaks at the dead cylinder. As you
increase the pressure from the compressor, if there is an air leak from an
exhaust valve, you’ll hear it clearly out of the exhaust stack. If it’s an
intake valve, listen at the throat of the carburetor. If it’s an air
injector you’ll hear I at the injector’s banjo fitting.
Dennis
Sent from my iPhone
On Apr 29, 2021, at 10:08 AM, Justin Drafts <draftsjust417(at)gmail.com>
wrote:
Thanks for all the quick replies folks... going to the hangar in a bit for
round 2.
I did try the rubber mallet approach to try and wallop the valves into
obedience, no luck but might need to try again.
Mm, I've always had success feeling for the tell-tale puff of air out the
open sparkplug hole to indicate the piston was starting it's way up on
compression stroke, then finalize the tdc sweet spot (slight prop rotation)
under ~40psi.
Once there, raise press to 80psi...
Has always worked well w/ consistent #'s, until yesterday.
With the 0/80 psi reading, esp on a cylinder I'd just checked at 74/80
psi, I *lean* to Dennis' idea of a stuck-open air input line. ?
But, not sure... I confess I'm a novice on in depth engine issues.
Justin
On Thu, Apr 29, 2021, 6:54 AM Greg Wrobel <clouddog22(at)gmail.com> wrote:
> Ok, I may need some help here. It's early, I haven't had my coffee yet
> and I am but the sharpest knife in the drawer. I saw where you started at
> the #1 cylinder and went counter clockwise. Then you said you got on the
> last cylinder (#2) and you started showing problems. The firing order is
> 1,3,5,7,9,2,4,6,8. In my simple world the last compression check should
> have been #8. Any chance you are just out of sequence?
>
> Greg "Clouddog" Wrobel
>
> On Thu, Apr 29, 2021, 00:03 Justin Drafts <draftsjust417(at)gmail.com>
> wrote:
>
>> Good evening all-
>>
>> A conundrum for you Housai engine experts; I need some advice to go fwd
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draftsjust417(at)gmail.co
Guest
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| Posted: Thu Apr 29, 2021 10:00 am Post subject: Housai engine question: compression check |
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|
Ya, I end up rotating (correct direction!) the prop thru a bit more to find each successive cylinder's TDC this way... admittedly it does take longer, but I'm on vacation, 
Will take a crack at the small air intake valves asap.. thankfully I have a battered old spare parts engine to practice on.
Justin
On Thu, Apr 29, 2021, 10:51 AM Walter Lannon <wlannon(at)shaw.ca (wlannon(at)shaw.ca)> wrote:
| Quote: | Hi Justin;
I can’t ever remember doing a leakdown test in anything but the firing order. One cylinder follows the last after 40 Deg. of rotation – piece of cake. However I note you started from the top and rotated CW as viewed from the cockpit. But it seems to my addled old brain that all British and the rest of the worlds engines (other than the US) turn the other way.
Best;
Walt
From: Justin Drafts (draftsjust417(at)gmail.com)
Sent: Thursday, April 29, 2021 8:24 AM
To: yak-list(at)matronics.com (yak-list(at)matronics.com)
Subject: Re: Housai engine question: compression check
YES I'm perpetually grateful for all the expert advice in the group! One day I might advance past Nanchang novice status...
Oh I wish it was my test equipment that had pooped the bed, but it read great for 8 out of 9 cylinders, even going back to randomly check #7 again after #2 and #3 showed that suspicious 0/80 psi reading (even tho 10 min prior, #3 showed a very good 74/80 psi). In a failure of that magnitude, of course the 1st and wisest resort is to question the test equipment, but this time I'm confident, sigh, it's working well.
Will go tap the valves again, and look into the air inlet valves.
Thankfully at first insp, rocker arms, springs, etc still looked factory new.
Good info on the check sequence, thanks all for insights.
Pls keep them coming, and will pass on any new info or solutions I find today...
Justin
On Thu, Apr 29, 2021, 7:57 AM Mark Pennington <pennington.construction.inc.1(at)gmail.com (pennington.construction.inc.1(at)gmail.com)> wrote:
| Quote: | Justin
I can't agree more that Dennis is on top of his radial engine info for sure, he has made my life easier on more than one occasion. The one thing that I haven't seen in the thread is you have confirmed your test equipment didn't die. The reason I ask is you dont hear air anywhere resulting in the very low reading.. Do you get a good compression check on any cylinders at this point.????? Also, based on my education from Dennis, following the firing order for a compression check is preferable.
With the experience you have from the past etc. I would check my compression checker.... Hope you find the issue. Please share with the group once you know.
Mark Pennington
N621CJ
On Thu, Apr 29, 2021 at 10:11 AM Justin Drafts <draftsjust417(at)gmail.com (draftsjust417(at)gmail.com)> wrote:
| Quote: | Thanks for all the quick replies folks... going to the hangar in a bit for round 2.
I did try the rubber mallet approach to try and wallop the valves into obedience, no luck but might need to try again.
Mm, I've always had success feeling for the tell-tale puff of air out the open sparkplug hole to indicate the piston was starting it's way up on compression stroke, then finalize the tdc sweet spot (slight prop rotation) under ~40psi.
Once there, raise press to 80psi...
Has always worked well w/ consistent #'s, until yesterday.
With the 0/80 psi reading, esp on a cylinder I'd just checked at 74/80 psi, I lean to Dennis' idea of a stuck-open air input line. ?
But, not sure... I confess I'm a novice on in depth engine issues.
Justin
On Thu, Apr 29, 2021, 6:54 AM Greg Wrobel <clouddog22(at)gmail.com (clouddog22(at)gmail.com)> wrote:
| Quote: | Ok, I may need some help here. It's early, I haven't had my coffee yet and I am but the sharpest knife in the drawer. I saw where you started at the #1 cylinder and went counter clockwise. Then you said you got on the last cylinder (#2) and you started showing problems. The firing order is 1,3,5,7,9,2,4,6,8. In my simple world the last compression check should have been #8. Any chance you are just out of sequence?
Greg "Clouddog" Wrobel
On Thu, Apr 29, 2021, 00:03 Justin Drafts <draftsjust417(at)gmail.com (draftsjust417(at)gmail.com)> wrote:
| Quote: | Good evening all-
A conundrum for you Housai engine experts; I need some advice to go fwd.
Doing the compression check today, I hit a weird wall.
With a partner I was checking cylinders starting with #1 at top, going CW when viewed from cockpit.
All #'s were good (avg 75/80 psi), until I got the last cylinder, #2. We got 0 psi on the pressure gauge.
Checking the pressure tester/gauges/fittings/hose, all are fine and perfectly functional.
So we double checked the previous cylinder, which had just 10 min prior tested at 74/80 psi.... now it also
showed 0/80 psi. ??
No obvious air leaks from oil breather, carburetor, or exhaust stack; no oil evident at bases of the cylinders;
the exhaust and intake stacks are good condition. I had flown the plane earlier in the day w/o any negative
indications.
Pulled the valve covers off to find the rocker arms, springs, etc in great condition, doing their job when we
slowly turned the prop thru by hand.
Stuck valves?
We tried the "rope trick" to slip a nylon cord into the cylinder thru the open sparkplug hole, then gently run
the piston up to TDC to try to reseat the possibly stuck-open valves. As yet, no help.
Fishing for advice & thoughts... what are we missing?
I've never seen a 0/80 psi reading... a bad piston ring or bad valve, should have SOME psi indication 30~60psi.
Thoughts? Pointers?
Thanks---
Justin Drafts
N280NC
|
|
|
|
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rmhou(at)yahoo.com
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| Posted: Thu Apr 29, 2021 2:08 pm Post subject: Housai engine question: compression check |
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At 0/80, you should hear the air coming out somewhere if the gauge is set and working properly. If not hearing air, may be a gauge issue.
On Thursday, April 29, 2021, 07:00:39 AM PDT, Greg Wrobel <clouddog22(at)gmail.com> wrote:
Ok, I may need some help here. It's early, I haven't had my coffee yet and I am but the sharpest knife in the drawer. I saw where you started at the #1 cylinder and went counter clockwise. Then you said you got on the last cylinder (#2) and you started showing problems. The firing order is 1,3,5,7,9,2,4,6,8. In my simple world the last compression check should have been #8. Any chance you are just out of sequence?Greg "Clouddog" Wrobel
On Thu, Apr 29, 2021, 00:03 Justin Drafts <draftsjust417(at)gmail.com (draftsjust417(at)gmail.com)> wrote:
| Quote: | Good evening all-
A conundrum for you Housai engine experts; I need some advice to go fwd.
Doing the compression check today, I hit a weird wall.
With a partner I was checking cylinders startingwith #1 at top, going CW when viewed from cockpit.
All #'s were good (avg 75/80 psi), until I got the last cylinder, #2. We got 0 psi on the pressure gauge.
Checking the pressure tester/gauges/fittings/hose, all are fine and perfectly functional.
So we double checked the previous cylinder, which had just 10 min prior tested at 74/80 psi... now it also
showed 0/80 psi. ??
No obvious air leaks from oil breather, carburetor, or exhaust stack; no oil evident at bases of the cylinders;
the exhaust and intake stacks are good condition. I had flown the plane earlier in the day w/o any negative
indications.
Pulled the valve covers off to find the rocker arms, springs, etc in great condition, doing their job when we
slowly turned the prop thru by hand.
Stuck valves?
We tried the "rope trick" to slip a nylon cord into the cylinder thru the open sparkplug hole, then gently run
the piston up to TDC to try to reseat the possibly stuck-open valves. As yet, no help.
Fishing for advice & thoughts.. what are we missing?
I've never seen a 0/80 psi reading... a bad piston ring or bad valve, should have SOME psi indication 30~60psi.
Thoughts? Pointers?
Thanks---
Justin Drafts
N280NC
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markbitterlich(at)embarqm
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| Posted: Thu Apr 29, 2021 2:41 pm Post subject: Housai engine question: compression check |
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I'd suggest removing all gages and start over. Remove one set of plugs.
Go to a good cylinder stick your thumb over a good cylinder empty plug hole and spin prop. It should blow your thumb right off with a good WHOOSH.
Now go to bad cylinder. Repeat process. If there is little to no WHOOSH, you have an engine issue.
If you get a good WHOOSH, you have a measurement issue.
With 0/80 there is zero compression and this simple test will tell you something.
Mark
-------- Original message --------
From: Robin Hou <rmhou(at)yahoo.com>
Date: 4/29/21 6:11 PM (GMT-05:00)
To: yak-list(at)matronics.com
Subject: Re: Yak-List: Re: Housai engine question: compression check
At 0/80, you should hear the air coming out somewhere if the gauge is set and working properly. If not hearing air, may be a gauge issue.
On Thursday, April 29, 2021, 07:00:39 AM PDT, Greg Wrobel <clouddog22(at)gmail.com> wrote:
Ok, I may need some help here. It's early, I haven't had my coffee yet and I am but the sharpest knife in the drawer. I saw where you started at the #1 cylinder and went counter clockwise. Then you said you got on the last cylinder (#2) and you started showing problems. The firing order is 1,3,5,7,9,2,4,6,8. In my simple world the last compression check should have been #8. Any chance you are just out of sequence?Greg "Clouddog" Wrobel
On Thu, Apr 29, 2021, 00:03 Justin Drafts <draftsjust417(at)gmail.com (draftsjust417(at)gmail.com)> wrote:
| Quote: | Good evening all-
A conundrum for you Housai engine experts; I need some advice to go fwd.
Doing the compression check today, I hit a weird wall.
With a partner I was checking cylinders startingwith #1 at top, going CW when viewed from cockpit.
All #'s were good (avg 75/80 psi), until I got the last cylinder, #2. We got 0 psi on the pressure gauge.
Checking the pressure tester/gauges/fittings/hose, all are fine and perfectly functional.
So we double checked the previous cylinder, which had just 10 min prior tested at 74/80 psi.... now it also
showed 0/80 psi. ??
No obvious air leaks from oil breather, carburetor, or exhaust stack; no oil evident at bases of the cylinders;
the exhaust and intake stacks are good condition. I had flown the plane earlier in the day w/o any negative
indications.
Pulled the valve covers off to find the rocker arms, springs, etc in great condition,doing theirjob when we
slowly turned the prop thru by hand.
Stuck valves?
We tried the "rope trick" to slip a nylon cord into the cylinder thru the open sparkplug hole, then gently run
the piston up to TDC to try to reseat the possibly stuck-open valves. As yet, no help.
Fishing for advice & thoughts... what are we missing?
I've never seen a 0/80 psi reading... a bad piston ring or bad valve, should have SOME psi indication 30~60psi.
Thoughts? Pointers?
Thanks---
Justin Drafts
N280NC
|
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draftsjust417(at)gmail.co
Guest
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| Posted: Thu Apr 29, 2021 5:29 pm Post subject: Housai engine question: compression check |
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Ok helpful gents and engine experts-
A fruitful sunny day spent (at) hangar with the suspect cylinders.
Checked the small starting air valve: definitely in good working order and closing as appropriate.
Pulling off rocker covers and watching the rocker arm and valve springs, I see there is
no gap at TDC between the rocker arm and top of the spring /stem for cylinders #2 and #3.
Just so I'm understanding valve lash / clearance correctly:
- the 0.010-0.014" clearance mentioned is supposed to be here at the red circle in the
attached pic, correct? (While the stem is at its highest point of travel/valve fully seated/TDC...)
-adjusting this clearance/lash requires turning the large adjustment screw at the green arrow, correct?
Based on the air I hear escaping the exhaust stack, I suspect the exhaust valves are sticking or
otherwise remaining open.
Not sure how I went from great compression #'s last year to 0/80 psi this year, but very little surprises
me in maintenance anymore.
Thoughts gents?
Thanks- Justin
On Thu, Apr 29, 2021 at 5:09 AM A. Dennis Savarese <dsavarese0812(at)bellsouth.net (dsavarese0812(at)bellsouth.net)> wrote:
| Quote: | --> Yak-List message posted by: "A. Dennis Savarese" <dsavarese0812(at)bellsouth.net (dsavarese0812(at)bellsouth.net)>
Also check the the air injector to make sure it is fully closed. It
too
has a very small valve inside of it about the size of a pencil eraser.
If the little valve spring is broken or the valve remains open, it will
of course affect the compression test.
Dennis
A. Dennis Savarese
334-546-8182
www.yak-52.com
On 4/28/2021 11:58 PM, Justin Drafts wrote:
> Good evening all-
>
> A conundrum for you Housai engine experts; I need some advice to go fwd.
> Doing the compression check today, I hit a weird wall.
>
> With a partner I was checking cylinders starting with #1 at top, going
> CW when viewed from cockpit.
> All #'s were good (avg 75/80 psi), until I got the last cylinder, #2.
> We got 0 psi on the pressure gauge.
>
> Checking the pressure tester/gauges/fittings/hose, all are fine and
> perfectly functional.
>
> So we double checked the previous cylinder, which had just 10 min
> prior tested at 74/80 psi.... now it also
> showed 0/80 psi. ??
> No obvious air leaks from oil breather, carburetor, or exhaust stack;
> no oil evident at bases of the cylinders;
> the exhaust and intake stacks are good condition. I had flown the
> plane earlier in the day w/o any negative
> indications.
>
> Pulled the valve covers off to find the rocker arms, springs, etc in
> great condition, doing their job when we
> slowly turned the prop thru by hand.
>
> Stuck valves?
>
> We tried the "rope trick" to slip a nylon cord into the cylinder thru
> the open sparkplug hole, then gently run
> the piston up to TDC to try to reseat the possibly stuck-open valves.
> As yet, no help.
>
> Fishing for advice & thoughts... what are we missing?
> I've never seen a 0/80 psi reading... a bad piston ring or bad valve,
> should have SOME psi indication 30~60psi.
>
> Thoughts? Pointers?
> Thanks---
>
> Justin Drafts
> N280NC
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