Severe Jittering Oil Pressure

by Alex Erdelyi in 912 / 914 Technical Questions 9 years ago

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Re: Severe Jittering Oil Pressure

by john raison » 7 years ago

john raison

1 19 0

Hi Frank,you may be right as im certainly not the only one with this problem,but you think it should be solvable,we originally thought it was just a problem with our MGL guage and all indicators led to this until we fitted the mechanical gauge to confirm,the motor has done 130 trouble free hours with this fluctuating pressure problem as i to had the same conclusion that it was fine as the readings were within the correct range. but after reading other posts i decided to investigate the problem further,i,m hoping other forum users can shed some light on this problem,but i hope to have a serious talk with the Rotax people at Sun and Fun in April
Cheers John ,

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Re: Severe Jittering Oil Pressure

by Durwood Sigrest » 7 years ago

Durwood Sigrest

0 3 0

I recently purchased a RV 12 with a 100 hour Rotax 912 UL. It ran fine the first 20 hours (it is now at 120 hours) and I am experiencing the fluxuating oil pressure, especially at 75% cruise or 4500 or less RPM. I have found and followed this forum thread after subscribing to the Rotax-Owner membership, hoping to secure an answer to the problem. Unfortunately, I have found mostly questions and "try this and try that" with no definitive answers. I do appreciate the very knowledgeable and good advice given by Allen and others". It does seem to be a fairly common problem, however, one if not resolved could result in an engine failure due to insufficient oiling.

My questions are:
1) Why has ROTAX not spent more time and effort into resolving this issue?
2) Have there been catastrophic engine failures inflight as a result?
3) Isn't this a design problem that should be dealt with in a Service Bulletin or AD?
4) Am I missing the proper location to get answers and learn of a definite fix for this problem?

The New Guy
Durwood

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Re: Severe Jittering Oil Pressure

by Durwood Sigrest » 7 years ago

Durwood Sigrest

0 3 0

I meant to credit Roger Lee for the good adice in my earlier post but could not remember his name until after I submitted it. Sorry Roger.

Durwood
the New Guy

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Re: Severe Jittering Oil Pressure

by Roger Lee » 7 years ago

Roger Lee

127 5.21k 4.79k

Howdy Durwood,

My questions are:
1) Why has ROTAX not spent more time and effort into resolving this issue?
Answer: The overwhelming number of engines don't have this problem. There were a few before the advent of the newer taller shouldered oil pressure plug screw because of the spring rubbing on the sidewall or the ball bearing chattering. Other things that cause this are poor grounding for the instruments and wiring. This can be an issue within an electronic instrument. Some need electronic program updates, some forgot to install resistors within the wiring and some have a poor grounding system or wire.

2) Have there been catastrophic engine failures in flight as a result?
Answer: No. The oil pressure within your engine should be just fine and isn't an in flight failure issue.

3) Isn't this a design problem that should be dealt with in a Service Bulletin or AD?
Answer: The overwhelming number of Rotax engine don't have this. Maybe only a few and I would bet the majority of those are not real within the engine. Could there be something causing this for real well sure, but then each operator needs to diagnose the why. i.e.: bad instrumentation, bad wire connections, real or not real fluctuations.

4) Am I missing the proper location to get answers and learn of a definite fix for this problem?
Answer:
No this is the right place for answers, but since this isn't a very common issue not many may have a ready made answer. It could be many things wrong.

I know some of these answers aren't as definitive as you may like, but all we can do long distance is keep trying. Sorry there is no quick fix since it must be tracked down through a process of elimination.

Let's keep trying. The answer is out there. :)

Roger Lee
LSRM-A & Rotax Instructor & Rotax IRC
Tucson, AZ Ryan Airfield (KRYN)
520-349-7056 Cell

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Re: Severe Jittering Oil Pressure

by Alex Erdelyi » 7 years ago

Alex Erdelyi

1 14 0

Folks,
I originated this thread sometime back out of frustration. Please look back through this thread for the details. I have a remotely mounted mechanical gauge, as well as a remotely mounted electronic sender. Both confirmed the jittering. Since repeatedly replacing the ball, spring and cup have led only to solutions that lasted a few engine hours, this time I looked further. My mechanic and I trial replaced each oil hose and the oil cooler. The trouble stayed, so obviously those components were not the issue. At this point, we replaced the oil pump housing with a used one he had laying around. That stopped the jittering. Using an inspection scope, we took a close look at the seat of the relief valve in the original housing. It showed severe galling. We then compared what we saw to another five used pumps. None of thos showed the unusual seat wear that we saw on mine. Armed with that information, I purchased a new pump housing from Rotax. With the new pump housing, all has been well so far (approx 15 hrs). I am now filing a warrantee claim to try to get my money back from Rotax. Wish me luck.
Alex

Thank you said by: Ken Ryan

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Severe Jittering Oil Pressure

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