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teamgrumman(at)yahoo.com
Guest

Posted: Wed Feb 22, 2012 7:38 pm Post subject: Oil Consumption

Look up the original work by Sam Heron.  The oil does not do the cooling.  At all.  You only want a minimum of oil on the valve stems for lubrication.  If you're flooding the stem with oil, some will get into the guide and the heat will cook it.  In sodium filled valves, the cooling is done through the valve seat and valve guide.

Sodium filled valves are used in a lot of top fuel dragsters.  For a reason.

        From: FLYaDIVE  <flyadive(at)gmail.com>

 To: teamgrumman-list(at)matronics.com 

 Sent: Wednesday, February 22, 2012 6:59 PM

 Subject: Re: Oil Consumption

  	  Quote: 	
		  Gary said:

 They are wrong.  Spraying extra oil on the valve stem causes coking on the valves.  Oil flow to the rocker boxes on an engine with sodium valves is intentionally limited.

The reality is, sodium filled valves do their work by direct metal to metal contact.  Or as close to that as possible. 

Gary:

Now that does not make sense.  I don't think anyone is around that was involved in the original design of the Lycoming engine.  The idea of a sodium filled valve and the extra transfer of heat because of the sodium is feasible but has proven short of goal.  Our problem has always been over heating of the exhaust valve and coking on the stem of that valve.  Continental uses solid stem valves and their failure mode is the same as Lycoming.   There is no way of collecting data as to how many Lycoming and Continental valve failures there are.

 BUT!  Isn't it COKING on the valve that causes the problem?  AND.. What is COKING?  Coking is the BURNING of OIL with the subsequent build up that causes the valve to stick.  When they stick in the DOWN position the piston comes up to smash the valve head and bend the valve shank.

 SO!  HOW WOULD ONE PREVENT THE COKING?  

BY LOWERING THE TEMPERATURE THAT CAUSES THE COKING.

 AND HOW WOULD ONE DO THAT?

BY INCREASING THE COOLING BY INCREASING THE OIL FLOW OVER THE VALVE STEM.  No, I'm not yelling, just emphasing the point.

Now, if this does not make sense, please explain why.  I cannot accept the idea that minimal oil for heat transfer is the way to go or the intent.

Barry

Here are my thoughts:

No mater how good or bad the heat transfer is between metal to meatal (something OIL is the medium that carries the heat away.

   	  Quote: 	
		  http://www.matronics.com/Navigator?TeamGrumma=====================

 [quote][b]

teamgrumman(at)yahoo.com
Guest

Posted: Wed Feb 22, 2012 7:39 pm Post subject: Oil Consumption

Not likely.  However, it wasn't long after talking to Lycoming that they came out with a common rocker for both intake and exhaust.

        From: 923TE <923te(at)att.net>

 To: "teamgrumman-list(at)matronics.com" <teamgrumman-list(at)matronics.com> 

 Sent: Wednesday, February 22, 2012 7:03 PM

 Subject: Re: Oil Consumption

 Gary,

Are you the reason Lycoming came out with just using the push rod with an oil gallery in it on all valves?

<><

On Feb 22, 2012, at 8:32 PM, Gary Vogt <teamgrumman(at)yahoo.com (teamgrumman(at)yahoo.com)> wrote:

[quote]he was old 28 years ago.  not sure if I have the ability to contact him at this point.

        From: 923te <923te(at)att.net (923te(at)att.net)>

 To: "teamgrumman-list(at)matronics.com (teamgrumman-list(at)matronics.com)" <teamgrumman-list(at)matronics.com (teamgrumman-list(at)matronics.com)> 

 Sent: Wednesday, February 22, 2012 10:46 AM

 Subject: Re: TeamGrumman-List: Oil Consumption

 Gary,

Any way to get Wayne here on the list?

It'd be great to have a Wayne's World Forum here;)

We need to get those guys head knowledge documented before they are all gone

On Feb 22, 2012, at 12:35 PM, Gary Vogt <teamgrumman(at)yahoo.com (teamgrumman(at)yahoo.com)> wrote:

[quote]I could give you all of the references to how to treat sodium filled valves, but then I'd have to go against everything Bill and Bill say.  

They are wrong.  Spraying extra oil on the valve stem causes coking on the valves.  Oil flow to the rocker boxes on an engine  with sodium valves is intentionally limited.

The reality is, sodium filled valves do their work by direct metal to metal contact.  Or as close to that as possible.  

The intakes could have seals.  The intake (originally) used a dribble method to keep oil flow to a minimum. With very little oil on the stem, very little was sucked in.   

The exhaust doesn't need them because the pressure pushes exhaust gases up the stem.  What little oil is squirted by the rocker is just enough to keep the stem lubricated.  

Lycoming had a knee jerk reaction to the valves in a Mooney.  It doesn't help.  Their research consisted of a corporate meeting.  Had that corporate decision not been a waste of manpower, time, and money, all new engines would have the retro fit.

30 years ago I called Lycoming and asked to talk to one of the engineers.  I wanted to know which rocker went on which valve.  You see, my <700 hr Cheetah had them one way on one side and the other way on the other side.  Both local AP/IAs didn't know.  I eventually talked to 6 engineers.  The last one gave me a phone number for a guy who worked for Lycoming 'in the old days.'  His name was  Wayne.  Nice guy.  He told me about the work done on the engines 'in the old days' and told me the correct order for the rockers.  My engine had been assembled wrong at the factory.

        From: 923te <923te(at)att.net (923te(at)att.net)>

 To: teamgrumman-list(at)matronics.com (teamgrumman-list(at)matronics.com) 

 Sent: Wednesday, February 22, 2012 9:24 AM

 Subject: Re:  TeamGrumman-List: Oil Consumption

          Bill Marvel and Bill Scott make for some very interesting reading and have  a very strong argument in the following articles:

 http://egaa.home.mindspring.com/valves.html

 Especially this article:

 http://egaa.home.mindspring.com/engine2.htm

 about the Lycoming TIO-540-AF1A Oil Cooled Exhaust Valve Guide  Kit

 Their arguments seem to be verified by what Lycoming did to cool the  exhaust valves with more oil flow onto the stems.

 I agree that the valve stem seals certainly go  counter to trying to cool them. 

 I guess it just depends on what you are trying  to do. It's a catch 22 isn't it?

 Sure would be great to see some R&D by  Lycolming on these issues. 

 [quote]   ---

BARRY CHECK 6

Joined: 15 Mar 2011
Posts: 738

Posted: Thu Feb 23, 2012 12:57 am Post subject: Oil Consumption

Gary:



I looked up Sam Heron and could not find anything.  Can you post a link?

IF - IF - The cooling is kept to a minimum to allow heat transfer someone has been feeding the industry a HUGE BLIVIT.  It makes better sense to keep the valve and guide clearance to a minimum to control valve and guide wear.  YOU DO NOT WANT THE VALVE SLOPPY AND FLOPPING AROUND.  Think of SB-388!!!  AND if you want to take the path that the heat is mainly or REQUIRED to be transferred through the Valve Head and Seat- That is true and all well and good, BUT... What do you think would happen if the valve head LOOSES contact surface because of SLOP between the valve guide and stem due to a larger SLOPPY fit?  

 AND what about the change in material of the valve seat years ago to better handle the heat?

AND there was a change in the valve guide material as well.  Maybe not to handle the heat transfer - But, to handle the ware. And where does ware come from?  

 No, I would not change the tolerance between valve stem and guide.  I would just REMOVE as much heat as possible while allowing two actions to take place:

1 - The material coefficient to keep the valve and guide tolerances.

 2 - The oil to remain in its optimum range.

Remember COKING is the burning of oil.  Keep the oil from burning and there is no coking.

No coking equals no valve failure - At least not from coking.

 



Barry

=============================

On Wed, Feb 22, 2012 at 10:38 PM, Gary Vogt <teamgrumman(at)yahoo.com (teamgrumman(at)yahoo.com)> wrote:

 [quote] Look up the original work by Sam Heron.  The oil does not do the cooling.  At all.  You only want a minimum of oil on the valve stems for lubrication.  If you're flooding the stem with oil, some will get into the guide and the heat will cook it.  In sodium filled valves, the cooling is done through the valve seat and valve guide.

 



Sodium filled valves are used in a lot of top fuel dragsters.  For a reason.

         From: FLYaDIVE  <flyadive(at)gmail.com (flyadive(at)gmail.com)>

 To: teamgrumman-list(at)matronics.com (teamgrumman-list(at)matronics.com) 

  Sent: Wednesday, February 22, 2012 6:59 PM

 Subject: Re: Oil Consumption

 

 

  

  	  Quote: 	
		  Gary said:

 They are wrong.  Spraying extra oil on the valve stem causes coking on the valves.  Oil flow to the rocker boxes on an engine with sodium valves is intentionally limited.

 



The reality is, sodium filled valves do their work by direct metal to metal contact.  Or as close to that as possible. 



	




   

Gary:

Now that does not make sense.  I don't think anyone is around that was involved in the original design of the Lycoming engine.  The idea of a sodium filled valve and the extra transfer of heat because of the sodium is feasible but has proven short of goal.  Our problem has always been over heating of the exhaust valve and coking on the stem of that valve.  Continental uses solid stem valves and their failure mode is the same as Lycoming.   There is no way of collecting data as to how many Lycoming and Continental valve failures there are.

  BUT!  Isn't it COKING on the valve that causes the problem?  AND... What is COKING?  Coking is the BURNING of OIL with the subsequent build up that causes the valve to stick.  When they stick in the DOWN position the piston comes up to smash the valve head and bend the valve shank.

  SO!  HOW WOULD ONE PREVENT THE COKING?  

BY LOWERING THE TEMPERATURE THAT CAUSES THE COKING.

  AND HOW WOULD ONE DO THAT?

BY INCREASING THE COOLING BY INCREASING THE OIL FLOW OVER THE VALVE STEM.  No, I'm not yelling, just emphasing the point.

   

Now, if this does not make sense, please explain why.  I cannot accept the idea that minimal oil for heat transfer is the way to go or the intent.

  



Barry



  

 



Here are my thoughts:

No mater how good or bad the heat transfer is between metal to meatal (something OIL is the medium that carries the heat away.

   



  

 	  Quote: 	
		  http://www.matronics.com/Navigator?TeamGrumma=====================



	


 

 

  

  	  Quote: 	
		  



st" target="_blank">http://www.matronics.com/Navigator?TeamGrumman-List

tp://forums.matronics.com

_blank">http://www.matronics.com/contribution



	




[b]

flyv35b(at)minetfiber.com
Guest

Posted: Thu Feb 23, 2012 5:24 am Post subject: Oil Consumption

On 2/22/2012 6:32 PM, Gary Vogt wrote:



 	  Quote: 	
		  > 30 years ago I called Lycoming and asked to talk to one of the

> engineers. I wanted to know which rocker went on which valve. You see,

> my <700 hr Cheetah had them one way on one side and the other way on

> the other side. Both local AP/IAs didn't know. I eventually talked to

> 6 engineers. The last one gave me a phone number for a guy who worked

> for Lycoming 'in the old days.' His name was Wayne. Nice guy. He told

> me about the work done on the engines 'in the old days' and told me

> the correct order for the rockers. My engine had been assembled wrong

> at the factory.


	


Bill Marvel had a new engine give to him from Lycoming free of charge 

because all the intake and exhaust rocker arms were swaped.  They since 

have gone to only one part (the previous exhaust rocker with the 

"squirt" hole) so that they can't be mixed up.  There is so little oil 

up there I'm not sure it makes any difference one way or the other.



Cliff

flyv35b(at)minetfiber.com
Guest

Posted: Thu Feb 23, 2012 5:32 am Post subject: Oil Consumption

On 2/22/2012 7:39 PM, Gary Vogt wrote:

 	  Quote: 	
		   Not likely. However, it wasn't long after talking to Lycoming that they

 came out with a common rocker for both intake and exhaust.


	


I suspect it was more likely due to Bill Marvel's dialog with Lycoming 

that resulted in this.



Cliff

flyv35b(at)minetfiber.com
Guest

Posted: Thu Feb 23, 2012 6:49 am Post subject: Oil Consumption

On 2/22/2012 6:59 PM, FLYaDIVE wrote:

 	  Quote: 	
		  > Gary said:

> They are wrong.  Spraying extra oil on the valve stem causes coking on

> the valves.  Oil flow to the rocker boxes on an engine with sodium

> valves is intentionally limited.

>

> The reality is, sodium filled valves do their work by direct metal to

> metal contact.  Or as close to that as possible.

 Gary:

 Now that does not make sense.  I don't think anyone is around that was

 involved in the original design of the Lycoming engine. The idea of a

 sodium filled valve and the extra transfer of heat because of the sodium

 is feasible but has proven short of goal.  Our problem has always been

 over heating of the exhaust valve and coking on the stem of that valve.

 Continental uses solid stem valves and their failure mode is the same as

 Lycoming.   There is no way of collecting data as to how many Lycoming

 and Continental valve failures there are.

 BUT!  Isn't it COKING on the valve that causes the problem?  AND... What

 is COKING?  Coking is the BURNING of OIL with the subsequent build up

 that causes the valve to stick.  When they stick in the DOWN position

 the piston comes up to smash the valve head and bend the valve shank.

 SO!  HOW WOULD ONE PREVENT THE COKING?

 BY LOWERING THE TEMPERATURE THAT CAUSES THE COKING.

 AND HOW WOULD ONE DO THAT?

 BY INCREASING THE COOLING BY INCREASING THE OIL FLOW OVER THE VALVE

 STEM.  No, I'm not yelling, just emphasing the point.

 Now, if this does not make sense, please explain why.  I cannot accept

 the idea that minimal oil for heat transfer is the way to go or the intent.

 Barry

 Here are my thoughts:

 No mater how good or bad the heat transfer is between metal to meatal

 (something OIL is the medium that carries the heat away.

"I looked up Sam Heron and could not find anything.  Can you post a link?

IF - IF - The cooling is kept to a minimum to allow heat transfer 

someone has been feeding the industry a HUGE BLIVIT.  It makes better 

sense to keep the valve and guide clearance to a minimum to control 

valve and guide wear.  YOU DO NOT WANT THE VALVE SLOPPY AND FLOPPING 

AROUND.  Think of SB-388!!!  AND if you want to take the path that the 

heat is mainly or REQUIRED to be transferred through the Valve Head and 

Seat- That is true and all well and good, BUT... What do you think would 

happen if the valve head LOOSES contact surface because of SLOP between 

the valve guide and stem due to a larger SLOPPY fit?

AND what about the change in material of the valve seat years ago to 

better handle the heat?

AND there was a change in the valve guide material as well.  Maybe not 

to handle the heat transfer - But, to handle the ware. And where does 

ware come from?

No, I would not change the tolerance between valve stem and guide.  I 

would just REMOVE as much heat as possible while allowing two actions to 

take place:

1 - The material coefficient to keep the valve and guide tolerances.

2 - The oil to remain in its optimum range.

Remember COKING is the burning of oil.  Keep the oil from burning and 

there is no coking.

No coking equals no valve failure - At least not from coking."

Barry

Gary is referring to an old SAE paper on sodium exhaust valve stems, 

which may have had an influence on Lycoming changing to their half inch 

sodium cooled exhaust valves.  I don't know that they intentionally 

limited the oil to the exhaust guide as that may have been dictated by 

the old automotive lifter design they chose to use years before.

At any rate there is precious little oil flow to the exhaust rocker 

area, especially on the RH side of the engine.  Certainly not enough to 

carry away any significant amount of heat, but just engouh to coke up 

the valve stem/guide under the right operating conditions.

In all the Tiger engines I have worked on and disassembled the valves 

from I don't ever recall seeing a stuck exhaust valve due to coking.  I 

think this happens much more often on the 150 hp engines and planes that 

are operated at low throttle settings for considerable time and at full 

rich mixture settings.  I think this is a faily uncommon failure more 

for a Tiger that is operated at high power and high rpm on x-country 

flights.  These engines tend to wear out the guides and looses up the 

clearance before they can coke up.

Since the sodium valves rely on transferring a good deal (maybe a 

majority) of the heat up the stem and through the guide to the head for 

cooling, then this interface is pretty important.  Continental engines 

transfer heat to the valve seat as the primary heat path.  Take a look 

at SKy Ranch Engineering Manual by John Schwaner for a detailed 

discussion of this.

The problem seems to be that guide wear is rapid under these conditions 

of high heat and material compatibility (hence the HC content guide 

change) and as the clearance increases the ability to transfer heat to 

the guide decreases, causing the valve to run hotter and wear the guide 

even quicker and fatigue the valve.  Eventually the valve head will 

break off as the valve is weakened and hits the seat cockeyed.  Happens 

all the time if you ignor the wear and let it go long enough.  Lycoming 

knows this, hence SB388C.  They have done little to really solve the 

problem.

I suspect that they may be some point where enough oil could be 

introduced and continuously flowed around the guide area to extract a 

significant amount of heat and lower the temperature to the point it 

could not coke up.  How much that would take, who knows.  I thought that 

was what Lycoming and Mooney were attempting to do on the parallel valve 

IO-540 engines in the Mooneys which were having serious valve problems 

on planes that only had 250 hours on them.  Owners were not happy.  Gary 

says that didn't work.  I don't know if that is so or not.  It would be 

nice to see the service reports and results after the change but that 

info probably is not available.

One thing is interesting is that Bill Marvel has loss of compression, 

exhaust valve leakage and wear problems with his old Tiger in time 

intervals as low as 250 hrs to 400 hrs on a routine basis.  He flew the 

plane entirely on x-country trips at altitude at 2700 rpm.  Since 

building his RV-8A with the same engine but with a CS prop operating at 

2300 rpm and full throttle he has had no valve problems in over 1200 hrs 

(or maybe more).

Personally, I'm not so sure that the sodium cooled exhaust valves have 

not aggravated the guide wear problem.  With the HC guides and SB388C 

the liability risk of an exhaust valve failure is reduced and the owner 

is just left with a low grain headache rather than a migraine one!

I disassembled a IO-520 Continental engine with 1700 hrs on it (TBO) and 

found the worst exhaust valve guide had only about .008" wear.  Cylinder 

bore wear was barely .003" at the top in the choke area.  The choke was 

gone and the cylinder was now straight, which according to Chuck Ney is 

better.  No cylinder work or any other work besides spark plugs and 

magneto inspection was ever done on this engine.  The engine in my 

Bonanza that was replaced by this one after overhaul went 700 hrs beyond 

TBO with very few cylinder problems.

Cliff

Discover

Joined: 26 Feb 2007
Posts: 429

Posted: Thu Feb 23, 2012 6:51 am Post subject: Oil Consumption

Bill Scott says he swaps parts in the hydraulic lifters to get the greatest clearances allowed by the Lycoming specifications. His research shows this parts swapping gets more oil on the valve stem. I had him do this on 2 of my engines after reading all their articles and having my Dad read the articles. Dad thought it was a good idea. He worked with sodium filled valves on B-29's and back in the day gained a lot of field knowledge on how to keep them running over the Pacific. I have often been bothered by the contradictory information. It makes sense that putting any oil on the valve stem would lead to coking if the stem is going to run hot enough to cook the oil. The valve guide material is self lubricating and theoretically doesn't need additional oil to work properly.

The answer Lycoming gives us is to measure "slop" and replace guides.

It would be great if Lycoming was owned by a huge company that had the incentive to develop a better solution. Like these guys

http://www.komatsu.com/CompanyInfo/profile/report/pdf/152-04_E.pdf

Ned

On Feb 23, 2012, at 7:24 AM, flyv35b <flyv35b(at)minetfiber.com> wrote:

 	  Quote: 	

 On 2/22/2012 6:32 PM, Gary Vogt wrote:

>> 30 years ago I called Lycoming and asked to talk to one of the

>> engineers. I wanted to know which rocker went on which valve. You see,

>> my <700 hr Cheetah had them one way on one side and the other way on

>> the other side. Both local AP/IAs didn't know. I eventually talked to

>> 6 engineers. The last one gave me a phone number for a guy who worked

>> for Lycoming 'in the old days.' His name was Wayne. Nice guy. He told

>> me about the work done on the engines 'in the old days' and told me

>> the correct order for the rockers. My engine had been assembled wrong

>> at the factory.

 Bill Marvel had a new engine give to him from Lycoming free of charge because all the intake and exhaust rocker arms were swaped.  They since have gone to only one part (the previous exhaust rocker with the "squirt" hole) so that they can't be mixed up.  There is so little oil up there I'm not sure it makes any difference one way or the other.

 Cliff

flyv35b(at)minetfiber.com
Guest

Posted: Thu Feb 23, 2012 7:22 am Post subject: Oil Consumption

On 2/23/2012 6:51 AM, 923TE wrote:

 	  Quote: 	

 Bill Scott says he swaps parts in the hydraulic lifters to get the greatest clearances allowed by the Lycoming specifications. His research shows this parts swapping gets more oil on the valve stem. I had him do this on 2 of my engines after reading all their articles and having my Dad read the articles. Dad thought it was a good idea. He worked with sodium filled valves on B-29's and back in the day gained a lot of field knowledge on how to keep them running over the Pacific. I have often been bothered by the contradictory information. It makes sense that putting any oil on the valve stem would lead to coking if the stem is going to run hot enough to cook the oil. The valve guide material is self lubricating and theoretically doesn't need additional oil to work properly.

 The answer Lycoming gives us is to measure "slop" and replace guides.

 It would be great if Lycoming was owned by a huge company that had the incentive to develop a better solution. Like these guys

 http://www.komatsu.com/CompanyInfo/profile/report/pdf/152-04_E.pdf

 Ned

 On Feb 23, 2012, at 7:24 AM, flyv35b<flyv35b(at)minetfiber.com>  wrote:

> 

>

> On 2/22/2012 6:32 PM, Gary Vogt wrote:

>

>>> 30 years ago I called Lycoming and asked to talk to one of the

>>> engineers. I wanted to know which rocker went on which valve. You see,

>>> my<700 hr Cheetah had them one way on one side and the other way on

>>> the other side. Both local AP/IAs didn't know. I eventually talked to

>>> 6 engineers. The last one gave me a phone number for a guy who worked

>>> for Lycoming 'in the old days.' His name was Wayne. Nice guy. He told

>>> me about the work done on the engines 'in the old days' and told me

>>> the correct order for the rockers. My engine had been assembled wrong

>>> at the factory.

>

> Bill Marvel had a new engine give to him from Lycoming free of charge because all the intake and exhaust rocker arms were swaped.  They since have gone to only one part (the previous exhaust rocker with the "squirt" hole) so that they can't be mixed up.  There is so little oil up there I'm not sure it makes any difference one way or the other.

>

> Cliff

>

What Bill is doing is testing the bleed down rate of the hydraulic unit 

and pickiing the ones with the highest bleed down rate for use on the 

exhaust valves.  That way they pump or bleed slightly more oil up the 

pushrod and to the rocker arm.  But it is still precious little.

BTW, Lycoming is owned by a large company called Textron.  They've got 

the money but no incentive and no competition for their medium power 4 

cylinder engines.  Heck, why change when you can sell more parts?  And 

the FAA makes it costly and difficult for anyone else to get in the 

game.  ECI has done a pretty good job but the cost is about the same.

Cliff

Discover

Joined: 26 Feb 2007
Posts: 429

Posted: Thu Feb 23, 2012 7:42 am Post subject: Oil Consumption

So all the old farts are dead and now it's our generation that's the old farts and were supposed to be the experts on 1940's technology?

Hmmm

Well I'm no expert but I'm thinking that maybe we should go back to what the really old farts were doing when they converted the engine for aircraft and just use push rods and rockers with holes in them on the intake and NOT the exhaust since the really old farts originally made it to conduct a dribble of oil ONLY ON THE INTAKE VALVE STEM

Is that how you built your current engine Gary?



On Feb 22, 2012, at 12:35 PM, Gary Vogt <teamgrumman(at)yahoo.com (teamgrumman(at)yahoo.com)> wrote:



[quote]I could give you all of the references to how to treat sodium filled valves, but then I'd have to go against everything Bill and Bill say.  

They are wrong.  Spraying extra oil on the valve stem causes coking on the valves.  Oil flow to the rocker boxes on an engine with sodium valves is intentionally limited.

The reality is, sodium filled valves do their work by direct metal to metal contact.  Or as close to that as possible.  

The intakes could have seals.  The intake (originally) used a dribble method to keep oil flow to a minimum. With very little oil on the stem, very little was sucked in.   

The exhaust doesn't need them because the pressure pushes exhaust gases up the stem.  What little oil is squirted by the rocker is just enough to keep the stem lubricated.  

Lycoming had a knee jerk reaction to the valves in a Mooney.  It doesn't help.  Their research consisted of a corporate meeting.  Had that corporate decision not been a waste of manpower, time, and money, all new engines would have the retro fit.

30 years ago I called Lycoming and asked to talk to one of the engineers.  I wanted to know which rocker went on which valve.  You see, my <700 hr Cheetah had them one way on one side and the other way on the other side.  Both local AP/IAs didn't know.  I eventually talked to 6 engineers.  The last one gave me a phone number for a guy who worked for Lycoming 'in the old days.'  His name was  Wayne.  Nice guy.  He told me about the work done on the engines 'in the old days' and told me the correct order for the rockers.  My engine had been assembled wrong at the factory.

        From: 923te <923te(at)att.net (923te(at)att.net)>

 To: teamgrumman-list(at)matronics.com (teamgrumman-list(at)matronics.com) 

 Sent: Wednesday, February 22, 2012 9:24 AM

 Subject: Re: TeamGrumman-List: Oil Consumption

  

 

          Bill Marvel and Bill Scott make for some very interesting reading and have  a very strong argument in the following articles:

 http://egaa.home.mindspring.com/valves.html

  

 Especially this article:

 http://egaa.home.mindspring.com/engine2.htm

 about the Lycoming TIO-540-AF1A Oil Cooled Exhaust Valve Guide  Kit

  

 Their arguments seem to be verified by what Lycoming did to cool the  exhaust valves with more oil flow onto the stems.

  

 I agree that the valve stem seals certainly go  counter to trying to cool them. 

 I guess it just depends on what you are trying  to do. It's a catch 22 isn't it?

  

 Sure would be great to see some R&D by  Lycolming on these issues. 

 [quote]   ---

Discover

Joined: 26 Feb 2007
Posts: 429

Posted: Thu Feb 23, 2012 8:31 am Post subject: Oil Consumption

BTW, Lycoming is owned by a large company called Textron.  They've got  

the money but no incentive and no competition for their medium power 4  

cylinder engines.  Heck, why change when you can sell more parts?   And 

the FAA makes it costly and difficult for anyone else to get in the  

game.  ECI has done a pretty good job but the cost is about the  same.



Cliff



I agree except that  Textron is less than 1/4 the size of Komatsu. 

 If Komatsu owned Textron then  maybe....

   [quote][b]

flyv35b(at)minetfiber.com
Guest

Posted: Thu Feb 23, 2012 8:46 am Post subject: Oil Consumption

On 2/23/2012 8:34 AM, 923te wrote:

 	  Quote: 	
		   BTW, Lycoming is owned by a large company called Textron. They've got

 the money but no incentive and no competition for their medium power 4

 cylinder engines. Heck, why change when you can sell more parts? And

 the FAA makes it costly and difficult for anyone else to get in the

 game. ECI has done a pretty good job but the cost is about the same.



 Cliff



 I agree except that Textron is less than 1/4 the size of Komatsu.

 If Komatsu owned Textron then maybe....



 *


	


I doubt it.  I think it is more related to desire and competition that 

forces you to make a better product and/or lower the cost.

teamgrumman(at)yahoo.com
Guest

Posted: Thu Feb 23, 2012 9:53 am Post subject: Oil Consumption

The guides on sodium filled valves are supposed to be tight.  Not sloppy.

Material change (guide) was to reduce wear and keep the clearance tight.

Material change (valve) was for wear.  Lead is a lubricant.  Take out the lead, you need a better valve.

I can't believe you can't find a reference to Sam Heron.

here is one reference.  I'm not going to do your homework.

http://www.agelessengines.com/j5.htm



        From: FLYaDIVE <flyadive(at)gmail.com>

 To: teamgrumman-list(at)matronics.com 

 Sent: Thursday, February 23, 2012 12:56 AM

 Subject: Re: Oil Consumption

  

 

 Gary:



I looked up Sam Heron and could not find anything.  Can you post a link?

IF - IF - The cooling is kept to a minimum to allow heat transfer someone has been feeding the industry a HUGE BLIVIT.  It makes better sense to keep the valve and guide clearance to a minimum to control valve and guide wear.  YOU DO NOT WANT THE VALVE SLOPPY AND FLOPPING AROUND.  Think of SB-388!!!  AND if you want to take the path that the heat is mainly or REQUIRED to be transferred through the Valve Head and Seat- That is true and all well and good, BUT... What do you think would happen if the valve head LOOSES contact surface because of SLOP between the valve guide and stem due to a larger SLOPPY fit?  

 AND what about the change in material of the valve seat years ago to better handle the heat?

AND there was a change in the valve guide material as well.  Maybe not to handle the heat transfer - But, to handle the ware. And where does ware come from?  

 No, I would not change the tolerance between valve stem and guide.  I would just REMOVE as much heat as possible while allowing two actions to take place:

1 - The material coefficient to keep the valve and guide tolerances.

 2 - The oil to remain in its optimum range.

Remember COKING is the burning of oil.  Keep the oil from burning and there is no coking.

No coking equals no valve failure - At least not from coking.

 



Barry

=============================

On Wed, Feb 22, 2012 at 10:38 PM, Gary Vogt <teamgrumman(at)yahoo.com (teamgrumman(at)yahoo.com)> wrote:

  	  Quote: 	
		   Look up the original work by Sam Heron.  The oil does not do the cooling.  At all.  You only want a minimum of oil on the valve stems for lubrication.  If you're flooding the stem with oil, some will get into the guide and the heat will cook it.  In sodium filled valves, the cooling is done through the valve seat and valve guide.

 



Sodium filled valves are used in a lot of top fuel dragsters.  For a reason.

         From: FLYaDIVE  <flyadive(at)gmail.com (flyadive(at)gmail.com)>

 To: teamgrumman-list(at)matronics.com (teamgrumman-list(at)matronics.com) 

  Sent: Wednesday, February 22, 2012 6:59 PM

 Subject: Re: Oil Consumption

 

 

  

  	  Quote: 	
		  Gary said:

 They are wrong.  Spraying extra oil on the valve stem causes coking on the valves.  Oil flow to the rocker boxes on an engine with sodium valves is intentionally limited.

 



The reality is, sodium filled valves do their work by direct metal to metal contact.  Or as close to that as possible. 



	




   

Gary:

Now that does not make sense.  I don't think anyone is around that was involved in the original design of the Lycoming engine.  The idea of a sodium filled valve and the extra transfer of heat because of the sodium is feasible but has proven short of goal.  Our problem has always been over heating of the exhaust valve and coking on the stem of that valve.  Continental uses solid stem valves and their failure mode is the same as Lycoming.   There is no way of collecting data as to how many Lycoming and Continental valve failures there are.

  BUT!  Isn't it COKING on the valve that causes the problem?  AND... What is COKING?  Coking is the BURNING of OIL with the subsequent build up that causes the valve to stick.  When they stick in the DOWN position the piston comes up to smash the valve head and bend the valve shank.

  SO!  HOW WOULD ONE PREVENT THE COKING?  

BY LOWERING THE TEMPERATURE THAT CAUSES THE COKING.

  AND HOW WOULD ONE DO THAT?

BY INCREASING THE COOLING BY INCREASING THE OIL FLOW OVER THE VALVE STEM.  No, I'm not yelling, just emphasing the point.

   

Now, if this does not make sense, please explain why.  I cannot accept the idea that minimal oil for heat transfer is the way to go or the intent.

  



Barry



  

 



Here are my thoughts:

No mater how good or bad the heat transfer is between metal to meatal (something OIL is the medium that carries the heat away.

   



  

 	  Quote: 	
		  http://www.matronics.com/Navigator?TeamGrumma=====================


	


 

 

  

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 [quote][b]

BARRY CHECK 6

Joined: 15 Mar 2011
Posts: 738

Posted: Thu Feb 23, 2012 9:59 am Post subject: Oil Consumption

Hi Cliff:



I believe it DOES make a difference.

Years back when I first purchased my plane I lost a cylinder.  Upon pulling the cylinder and doing an inspection I found that the Exhaust and Intake Rockers were swapped.  The Intake Rocker for those that do not know has the oil squirt hole facing AWAY from the valve [they face the valve on the Exhaust].  This may not matter on the INTAKE Valve but - - - Inspection showed High Heat on the Rocker Arm and on the Rocker Shaft ONLY in the area of the Intake Rocker- - WHERE it was incorrectly installed on the Exhaust Valve..

 Is this 100% proof... Maybe not! BUT, it was the ONLY Rocker that was mixed up.

When I had the engine MAJORED, I requested that ALL the rockers be EXHAUST ROCKERS.  And there is a SB by Lycoming allowing it.  I did the research and had to inform the engine shop of this SB.  

 



Barry

On Thu, Feb 23, 2012 at 8:24 AM, flyv35b <flyv35b(at)minetfiber.com (flyv35b(at)minetfiber.com)> wrote:

 [quote]--> TeamGrumman-List message posted by: flyv35b <flyv35b(at)minetfiber.com (flyv35b(at)minetfiber.com)>

  



 On 2/22/2012 6:32 PM, Gary Vogt wrote:

 

  	  Quote: 	
		   	  Quote: 	
		   30 years ago I called Lycoming and asked to talk to one of the

 engineers. I wanted to know which rocker went on which valve. You see,

 my <700 hr Cheetah had them one way on one side and the other way on

 the other side. Both local AP/IAs didn't know. I eventually talked to

 6 engineers. The last one gave me a phone number for a guy who worked

 for Lycoming 'in the old days.' His name was Wayne. Nice guy. He told

 me about the work done on the engines 'in the old days' and told me

 the correct order for the rockers. My engine had been assembled wrong

 at the factory.

 	
	
 



 Bill Marvel had a new engine give to him from Lycoming free of charge because all the intake and exhaust rocker arms were swaped.  They since have gone to only one part (the previous exhaust rocker with the "squirt" hole) so that they can't be mixed up.  There is so little oil up there I'm not sure it makes any difference one way or the other.

  

 Cliff



 

 ====================================

 List" target="_blank">http://www.matronics.com/Navigator?TeamGrumman-List

 ====================================

 http://forums.matronics.com

 ====================================

 le, List Admin.

 ="_blank">http://www.matronics.com/contribution

 ====================================

 

 

 

 



[b]

teamgrumman(at)yahoo.com
Guest

Posted: Thu Feb 23, 2012 10:21 am Post subject: Oil Consumption

I wonder if seals would help?

        From: 923TE <923te(at)att.net>

 To: "teamgrumman-list(at)matronics.com" <teamgrumman-list(at)matronics.com> 

 Sent: Thursday, February 23, 2012 6:51 AM

 Subject: Re: TeamGrumman-List: Oil Consumption

 --> TeamGrumman-List message posted by: 923TE <923te(at)att.net (923te(at)att.net)>

Bill Scott says he swaps parts in the hydraulic lifters to get the greatest clearances allowed by the Lycoming specifications. His research shows this parts swapping gets more oil on the valve stem. I had him do this on 2 of my engines after reading all their articles and having my Dad read the articles. Dad thought it was a good idea. He worked with sodium filled valves on B-29's and back in the day gained a lot of field knowledge on how to keep them running over the Pacific. I have often been bothered by the contradictory information. It makes sense that putting any oil on the valve stem would lead to coking if the stem is going to run hot enough to cook the oil. The valve guide material is self lubricating and theoretically doesn't need additional oil to work properly.

The answer Lycoming gives us is to  measure "slop" and replace guides.

It would be great if Lycoming was owned by a huge company that had the incentive to develop a better solution. Like these guys

http://www.komatsu.com/CompanyInfo/profile/report/pdf/152-04_E.pdf

Ned

On Feb 23, 2012, at 7:24 AM, flyv35b <flyv35b(at)minetfiber.com (flyv35b(at)minetfiber.com)> wrote:

[quote] --> TeamGrumman-List message posted by: flyv35b <flyv35b(at)minetfiber.com (flyv35b(at)minetfiber.com)>

 On 2/22/2012 6:32 PM, Gary Vogt wrote:

>> 30 years ago I called Lycoming and asked to talk to one of the

>> engineers. I wanted to know which rocker went on which valve. You see,

>> my <700 hr Cheetah had them one way on one side and the other way on

>> the other side. Both local AP/IAs  didn't know. I eventually talked to

>> 6 engineers. The last one gave me a phone number for a guy who worked

>> for Lycoming 'in the old days.' His name was Wayne. Nice guy. He told

>> me about the work done on the engines 'in the old days' and told me

>> the correct order for the rockers. My engine had been assembled wrong

>> at the factory.

 Bill Marvel had a new engine give to him from Lycoming free of charge because all the intake and exhaust rocker arms were swaped.  They since have gone to only one part (the previous exhaust rocker with the "squirt" hole) so that they can't be mixed up.  There is so little oil up there I'm not sure it makes any difference one way or the other.

 Cliff

teamgrumman(at)yahoo.com
Guest

Posted: Thu Feb 23, 2012 10:23 am Post subject: Oil Consumption

"Is that how you built your current engine Gary?"

Just using factory rockers.

        From: 923te <923te(at)att.net>

 To: "teamgrumman-list(at)matronics.com" <teamgrumman-list(at)matronics.com> 

 Sent: Thursday, February 23, 2012 7:41 AM

 Subject: Re: Oil Consumption

 So all the old farts are dead and now it's our generation that's the old farts and were supposed to be the experts on 1940's technology?

Hmmm

Well I'm no expert but I'm thinking that maybe we should go back to what the really old farts were doing when they converted the engine for aircraft and just use push rods and rockers with holes in them on the intake and NOT the exhaust since the really old farts originally made it to conduct a dribble of oil ONLY ON THE INTAKE VALVE STEM

Is that how you built your current engine Gary?

On Feb 22, 2012, at 12:35 PM, Gary Vogt <teamgrumman(at)yahoo.com (teamgrumman(at)yahoo.com)> wrote:

[quote]I could give you all of the references to how to treat sodium filled valves, but then I'd have to go against everything Bill and Bill say.  

They are wrong.  Spraying extra oil on the valve stem causes coking on the valves.  Oil flow to the rocker boxes on an engine with sodium valves is intentionally limited.

The reality is, sodium filled valves do their work by direct metal to metal contact.  Or as close to that as possible.  

The intakes could have seals.  The intake (originally) used a dribble  method to keep oil flow to a minimum. With very little oil on the stem, very little was sucked in.   

The exhaust doesn't need them because the pressure pushes exhaust gases up the stem.  What little oil is squirted by the rocker is just enough to keep the stem lubricated.  

Lycoming had a knee jerk reaction to the valves in a Mooney.  It doesn't help.  Their research consisted of a corporate meeting.  Had that corporate decision not been a waste of manpower, time, and money, all new engines would have the retro fit.

30 years ago I called Lycoming and asked to talk to one of the engineers.  I wanted to know which rocker went on which valve.  You see, my <700 hr Cheetah had them one way on one side and the other way on the other side.  Both local AP/IAs didn't know.  I eventually talked to 6 engineers.  The last one gave me a phone number for a guy who worked for Lycoming 'in the old days.'  His name was  Wayne.  Nice guy.  He told me about the work done on the engines 'in the old days' and told me the correct order for the rockers.  My engine had been assembled wrong at the factory.

        From: 923te <923te(at)att.net (923te(at)att.net)>

 To: teamgrumman-list(at)matronics.com (teamgrumman-list(at)matronics.com) 

 Sent: Wednesday, February 22, 2012 9:24 AM

 Subject: Re:  Oil Consumption

          Bill Marvel and Bill Scott make for some very interesting reading and have  a very strong argument in the following articles:

 http://egaa.home.mindspring.com/valves.html

 Especially this article:

 http://egaa.home.mindspring.com/engine2.htm

 about the Lycoming TIO-540-AF1A Oil Cooled Exhaust Valve Guide  Kit

 Their arguments seem to be verified by what Lycoming did to cool the  exhaust valves with more oil flow onto the stems.

 I agree that the valve stem seals certainly go  counter to trying to cool them. 

 I guess it just depends on what you are trying  to do. It's a catch 22 isn't it?

 Sure would be great to see some R&D by  Lycolming on these issues. 

 [quote]   ---

BARRY CHECK 6

Joined: 15 Mar 2011
Posts: 738

Posted: Thu Feb 23, 2012 10:26 am Post subject: Oil Consumption

Gary:



Thanks for the obscure post & website address.  But come on- - - Anyone else find anything on Sam Heron?  And what does this have to do with 'more oil won't help!'  That article is only a history that Sam came up with the idea of sodium filled valves - Way back in 1916.  It does not shed light on today with the same problem they had in 1916.

 You would have thunk they would have learned from then to now...  But, then again it is the lawyers that run engine companies - Not Engineers.

Barry





 On Thu, Feb 23, 2012 at 12:51 PM, Gary Vogt <teamgrumman(at)yahoo.com (teamgrumman(at)yahoo.com)> wrote:

[quote] The guides on sodium filled valves are supposed to be tight.  Not sloppy.



 

Material change (guide) was to reduce wear and keep the clearance tight.

Material change (valve) was for wear.  Lead is a lubricant.  Take out the lead, you need a better valve.

 



I can't believe you can't find a reference to Sam Heron.

here is one reference.  I'm not going to do your homework.

http://www.agelessengines.com/j5.htm

 





         From: FLYaDIVE <flyadive(at)gmail.com (flyadive(at)gmail.com)>

 To: teamgrumman-list(at)matronics.com (teamgrumman-list(at)matronics.com) 

  

Sent: Thursday, February 23, 2012 12:56 AM

 Subject: Re: Oil Consumption

 

 

  

 Gary:



I looked up Sam Heron and could not find anything.  Can you post a link?

IF - IF - The cooling is kept to a minimum to allow heat transfer someone has been feeding the industry a HUGE BLIVIT.  It makes better sense to keep the valve and guide clearance to a minimum to control valve and guide wear.  YOU DO NOT WANT THE VALVE SLOPPY AND FLOPPING AROUND.  Think of SB-388!!!  AND if you want to take the path that the heat is mainly or REQUIRED to be transferred through the Valve Head and Seat- That is true and all well and good, BUT... What do you think would happen if the valve head LOOSES contact surface because of SLOP between the valve guide and stem due to a larger SLOPPY fit?  

  AND what about the change in material of the valve seat years ago to better handle the heat?

AND there was a change in the valve guide material as well.  Maybe not to handle the heat transfer - But, to handle the ware. And where does ware come from?  

  No, I would not change the tolerance between valve stem and guide.  I would just REMOVE as much heat as possible while allowing two actions to take place:

1 - The material coefficient to keep the valve and guide tolerances.

  2 - The oil to remain in its optimum range.

Remember COKING is the burning of oil.  Keep the oil from burning and there is no coking.

No coking equals no valve failure - At least not from coking.

  



Barry



=============================

On Wed, Feb 22, 2012 at 10:38 PM, Gary Vogt <teamgrumman(at)yahoo.com (teamgrumman(at)yahoo.com)> wrote:

  

 	  Quote: 	
		    Look up the original work by Sam Heron.  The oil does not do the cooling.  At all.  You only want a minimum of oil on the valve stems for lubrication.  If you're flooding the stem with oil, some will get into the guide and the heat will cook it.  In sodium filled valves, the cooling is done through the valve seat and valve guide.

  



Sodium filled valves are used in a lot of top fuel dragsters.  For a reason.

  

       From: FLYaDIVE  <flyadive(at)gmail.com (flyadive(at)gmail.com)>

 To: teamgrumman-list(at)matronics.com (teamgrumman-list(at)matronics.com) 

   Sent: Wednesday, February 22, 2012 6:59 PM

 Subject: Re: Oil Consumption

 



  

  

  	  Quote: 	
		  Gary said:

 They are wrong.  Spraying extra oil on the valve stem causes coking on the valves.  Oil flow to the rocker boxes on an engine with sodium valves is intentionally limited.

 



The reality is, sodium filled valves do their work by direct metal to metal contact.  Or as close to that as possible. 



	


    

Gary:

Now that does not make sense.  I don't think anyone is around that was involved in the original design of the Lycoming engine.  The idea of a sodium filled valve and the extra transfer of heat because of the sodium is feasible but has proven short of goal.  Our problem has always been over heating of the exhaust valve and coking on the stem of that valve.  Continental uses solid stem valves and their failure mode is the same as Lycoming.   There is no way of collecting data as to how many Lycoming and Continental valve failures there are.

   BUT!  Isn't it COKING on the valve that causes the problem?  AND... What is COKING?  Coking is the BURNING of OIL with the subsequent build up that causes the valve to stick.  When they stick in the DOWN position the piston comes up to smash the valve head and bend the valve shank.

   SO!  HOW WOULD ONE PREVENT THE COKING?  

BY LOWERING THE TEMPERATURE THAT CAUSES THE COKING.

   AND HOW WOULD ONE DO THAT?

BY INCREASING THE COOLING BY INCREASING THE OIL FLOW OVER THE VALVE STEM.  No, I'm not yelling, just emphasing the point.

    

Now, if this does not make sense, please explain why.  I cannot accept the idea that minimal oil for heat transfer is the way to go or the intent.

   



Barry



   

 

Here are my thoughts:

No mater how good or bad the heat transfer is between metal to meatal (something OIL is the medium that carries the heat away.

    



  



 	  Quote: 	
		  http://www.matronics.com/Navigator?TeamGrumma=====================



	


 

 

  

  	  Quote: 	
		  



st" target="_blank">http://www.matronics.com/Navigator?TeamGrumman-List

tp://forums.matronics.com

_blank">http://www.matronics.com/contribution



	




http://www.matronics.com/Navigator?TeamGruank" href="http://forums.matronics.com">http://forums.matronics.com rel="nofollow" target="_blank" href="http://www.matronics.com/contri===



	


 

 

  

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[b]

teamgrumman(at)yahoo.com
Guest

Posted: Thu Feb 23, 2012 8:00 pm Post subject: Oil Consumption

I found an obscure paper written by Heron many years ago.  Come on Barry, get creative and find.

        From: FLYaDIVE <flyadive(at)gmail.com>

 To: teamgrumman-list(at)matronics.com 

 Sent: Thursday, February 23, 2012 10:26 AM

 Subject: Re: Oil Consumption

 Gary:

Thanks for the obscure post & website address.  But come on- - - Anyone else find anything on Sam Heron?  And what does this have to do with 'more oil won't help!'  That article is only a history that Sam came up with the idea of sodium filled valves - Way back in 1916.  It does not shed light on today with the same problem they had in 1916.

 You would have thunk they would have learned from then to now...  But, then again it is the lawyers that run engine companies - Not Engineers.

Barry

 On Thu, Feb 23, 2012 at 12:51 PM, Gary Vogt <teamgrumman(at)yahoo.com (teamgrumman(at)yahoo.com)> wrote:

 	  Quote: 	
		   The guides on sodium filled valves are supposed to be tight.  Not sloppy.

Material change (guide) was to reduce wear and keep the clearance tight.

Material change (valve) was for wear.  Lead is a lubricant.  Take out the lead, you need a better valve.

I can't believe you can't find a reference to Sam Heron.

here is one reference.  I'm not going to do your homework.

http://www.agelessengines.com/j5.htm

         From: FLYaDIVE <flyadive(at)gmail.com (flyadive(at)gmail.com)>

 To: teamgrumman-list(at)matronics.com (teamgrumman-list(at)matronics.com) 

Sent: Thursday, February 23, 2012 12:56 AM

 Subject: Re: TeamGrumman-List: Oil Consumption

 Gary:

I looked up Sam Heron and could not find anything.  Can you post a link?

IF - IF - The cooling is kept to a minimum to allow heat transfer someone has been feeding the industry a HUGE BLIVIT.  It makes better sense to keep the valve and guide clearance to a minimum to control valve and guide wear.  YOU DO NOT WANT THE VALVE SLOPPY AND FLOPPING AROUND.  Think of SB-388!!!  AND if you want to take the path that the heat is mainly or REQUIRED to be transferred through the Valve Head and Seat- That is true and all well and good, BUT... What do you think would happen if the valve head LOOSES contact surface because of SLOP between the valve guide and stem due to a larger SLOPPY fit?  

  AND what about the change in material of the valve seat years ago to better handle the heat?

AND there was a change in the valve guide material as well.  Maybe not to handle the heat transfer - But, to handle the ware. And where does ware come from?  

  No, I would not change the tolerance between valve stem and guide.  I would just REMOVE as much heat as possible while allowing two actions to take place:

1 - The material coefficient to keep the valve and guide tolerances.

  2 - The oil to remain in its optimum range.

Remember COKING is the burning of oil.  Keep the oil from burning and there is no coking.

No coking equals no valve failure - At least not from coking.

Barry

=============================

On Wed, Feb 22, 2012 at 10:38 PM, Gary Vogt <teamgrumman(at)yahoo.com (teamgrumman(at)yahoo.com)> wrote:

 	  Quote: 	
		    Look up the original work by Sam Heron.  The oil does not do the cooling.  At all.  You only want a minimum of oil on the valve stems for lubrication.  If you're flooding the stem with oil, some will get into the guide and the heat will cook it.  In sodium filled valves, the cooling is done through the valve seat and valve guide.

Sodium filled valves are used in a lot of top fuel dragsters.  For a reason.

       From: FLYaDIVE  <flyadive(at)gmail.com (flyadive(at)gmail.com)>

 To: teamgrumman-list(at)matronics.com (teamgrumman-list(at)matronics.com) 

   Sent: Wednesday, February 22, 2012 6:59 PM

 Subject: Re: TeamGrumman-List: Oil Consumption

  	  Quote: 	
		  Gary said:

 They are wrong.  Spraying extra oil on the valve stem causes coking on the valves.  Oil flow to the rocker boxes on an engine with sodium valves is intentionally limited.

The reality is, sodium filled valves do their work by direct metal to metal contact.  Or as close to that as possible. 

Gary:

Now that does not make sense.  I don't think anyone is around that was involved in the original design of the Lycoming engine.  The idea of a sodium filled valve and the extra transfer of heat because of the sodium is feasible but has proven short of goal.  Our problem has always been over heating of the exhaust valve and coking on the stem of that valve.  Continental uses solid stem valves and their failure mode is the same as Lycoming.   There is no way of collecting data as to how many Lycoming and Continental valve failures there are.

   BUT!  Isn't it COKING on the valve that causes the problem?  AND... What is COKING?  Coking is the BURNING of OIL with the subsequent build up that causes the valve to stick.  When they stick in the DOWN position the piston comes up to smash the valve head and bend the valve shank.

   SO!  HOW WOULD ONE PREVENT THE COKING?  

BY LOWERING THE TEMPERATURE THAT CAUSES THE COKING.

   AND HOW WOULD ONE DO THAT?

BY INCREASING THE COOLING BY INCREASING THE OIL FLOW OVER THE VALVE STEM.  No, I'm not yelling, just emphasing the point.

Now, if this does not make sense, please explain why.  I cannot accept the idea that minimal oil for heat transfer is the way to go or the intent.

Barry

Here are my thoughts:

No mater how good or bad the heat transfer is between metal to meatal (something OIL is the medium that carries the heat away.

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		  http://www.matronics.com/Navigator?TeamGrumma=====================

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