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KeysFox
Joined: 05 Jan 2009
Posts: 137
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 Posted: Wed May 29, 2013 8:10 am Post subject: repair vs new vs overhaul |
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Roger,
My early s/n 912 in a model IV Kitfox shows evidence of right rear exhaust
leakage at the head to exhaust pipe.
Upon removal of the exhaust system I note that both rear exhaust pipes are
sloppy in their fit to the heads, so I suspect an overheat problem, at
least right at the exhaust ports??
So I bet I am in for two new heads (ouch $) and two new exhaust pipe ends
welded onto the existing pipes. Does this sound right?
Oh, the two rear exhaust pipes do not push up into the front head exhaust
ports, probably because of a bit of exhaust crud build up on the old
pipes, however the pipes do look round to my lay person's eye with a bit
of surface crud on the outside where they fit into the exhaust port.
I bought the plane about 15 years ago with 60 hours at that time, have
flown it another roughly 400 and have never seen any indication of
overheating on gauges, no leaking of oil at heads indicating warpage of
heads nor has the coolant boiled over at least since I have owned it?
So next question, what might be the cause? If I put two new heads on is
the problem likely to recur? Any guidance here could be very useful.
Since new heads are expensive, what are the rules of thumb about just
selling the engine and getting a "factory overhaul" if such exists, or
getting aa new engine on exchange from Rotax? I recall hearing that Rotax
offered a "good deal" on new engines in exchange for old engines, if the
case of the old engine is good?
I bet others would be interested in some general guidelines on this from a
trained and experienced Rotax specialist such as yourself.
Thanks in advance for any guidance!
BJ
Kitfox IV 1050, Rotax 912
bjones(at)dmv.com
443-480-1023
| Quote: |
Hi Hugh,
The problem has been that not everyone has a gascolator or a fuel filter
far enough downstream. the main hose offenders isn't from hose before the
fuel pump because it has a filter screen inside, but from hose past the
pump. The fuel hose from the pump pressure side out is a problem at times.
Some 912's have the stainless steel lines mounted from the fuel
distribution block mounted on the carb balance tube, some don't. Some have
the red Teflon fuel line from this point and some have just rubber fuel
line right out of the pump to the carbs.
Read this and you'll get a better handle on what some of the issues have
been. My original post here was to just give you another tool in your
mental toolbox for the "just in case" scenario.
http://www.rotax-owner.com/rotax-blog/item/21-rotax-5-year-rubber-replacement-the-installation-considerations
--------
Roger Lee
Tucson, Az.
Light Sport Repairman - Maintenance Rated
Rotax Repair Center - Heavy Maint. Rated
Home 520-574-1080 TRY HOME FIRST
Cell 520-349-7056
Read this topic online here:
http://forums.matronics.com/viewtopic.php?p=399964#399964
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| | - The Matronics RotaxEngines-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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_________________
B Jones
N154K
443-480-1023 |
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peteohms
Joined: 31 Oct 2007
Posts: 224
Location: Leander, TX
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| Posted: Wed May 29, 2013 9:08 am Post subject: repair vs new vs overhaul |
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Your not flying enough. 
Pete
On May 29, 2013, at 11:09 AM, bjones(at)dmv.com wrote:
| Quote: |
Roger,
My early s/n 912 in a model IV Kitfox shows evidence of right rear exhaust
leakage at the head to exhaust pipe.
Upon removal of the exhaust system I note that both rear exhaust pipes are
sloppy in their fit to the heads, so I suspect an overheat problem, at
least right at the exhaust ports??
So I bet I am in for two new heads (ouch $) and two new exhaust pipe ends
welded onto the existing pipes. Does this sound right?
Oh, the two rear exhaust pipes do not push up into the front head exhaust
ports, probably because of a bit of exhaust crud build up on the old
pipes, however the pipes do look round to my lay person's eye with a bit
of surface crud on the outside where they fit into the exhaust port.
I bought the plane about 15 years ago with 60 hours at that time, have
flown it another roughly 400 and have never seen any indication of
overheating on gauges, no leaking of oil at heads indicating warpage of
heads nor has the coolant boiled over at least since I have owned it?
So next question, what might be the cause? If I put two new heads on is
the problem likely to recur? Any guidance here could be very useful.
Since new heads are expensive, what are the rules of thumb about just
selling the engine and getting a "factory overhaul" if such exists, or
getting aa new engine on exchange from Rotax? I recall hearing that Rotax
offered a "good deal" on new engines in exchange for old engines, if the
case of the old engine is good?
I bet others would be interested in some general guidelines on this from a
trained and experienced Rotax specialist such as yourself.
Thanks in advance for any guidance!
BJ
Kitfox IV 1050, Rotax 912
bjones(at)dmv.com
443-480-1023
>
>
> Hi Hugh,
>
> The problem has been that not everyone has a gascolator or a fuel filter
> far enough downstream. the main hose offenders isn't from hose before the
> fuel pump because it has a filter screen inside, but from hose past the
> pump. The fuel hose from the pump pressure side out is a problem at times.
> Some 912's have the stainless steel lines mounted from the fuel
> distribution block mounted on the carb balance tube, some don't. Some have
> the red Teflon fuel line from this point and some have just rubber fuel
> line right out of the pump to the carbs.
>
> Read this and you'll get a better handle on what some of the issues have
> been. My original post here was to just give you another tool in your
> mental toolbox for the "just in case" scenario.
>
> http://www.rotax-owner.com/rotax-blog/item/21-rotax-5-year-rubber-replacement-the-installation-considerations
>
> --------
> Roger Lee
> Tucson, Az.
> Light Sport Repairman - Maintenance Rated
> Rotax Repair Center - Heavy Maint. Rated
> Home 520-574-1080 TRY HOME FIRST
> Cell 520-349-7056
>
>
>
>
> Read this topic online here:
>
> http://forums.matronics.com/viewtopic.php?p=399964#399964
|
| | - The Matronics RotaxEngines-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:
http://www.matronics.com/Navigator?RotaxEngines-List |
|
_________________
Pete
Leander, TX
Kitfox III, 912ul, Grove |
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Roger Lee
Joined: 10 Jan 2006
Posts: 1464
Location: Tucson, Az.
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| Posted: Wed May 29, 2013 2:55 pm Post subject: Re: repair vs new vs overhaul |
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Hi BJ,
I doubt that high temp issue caused this. The most likely cause is the pulsation from the exhaust causes the tubes to vibrate and move which wears down the metal (chafing). Some wear completely through. I would bet your engine is just fine and wouldn't think about a new one or rebuilding. I would however replace the exhaust. The joints should be lubed every couple hundred hours with copper anti seize. Also make sure any nuts, bolts and springs on the exhaust are tight and or up at torque. This will help eliminate the wear.
| | - The Matronics RotaxEngines-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:
http://www.matronics.com/Navigator?RotaxEngines-List |
|
_________________
Roger Lee
Tucson, Az.
Rotax Instructor & Rotax IRC
Light Sport Repairman
Home 520-574-1080 TRY HOME FIRST
Cell 520-349-7056 |
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