912S Reduced Oil Pressure.

by Don Cramer in 912iS Technical Questions 13 years ago

We own 2 MTO Sport Gyrocopters in our flying school www.flydalby.com in Queensland Australia.
As each engine has approached the 250 hr mark the oil pressure has reduced from approximately 3.5 bar to just over 2 bar. When attempting to address this situation with number one 912 (now at 550 hrs) the Australian Rotax importer sold me an extra shim and spring for the pressure regulator and explained how this magic will fix the problem, but the oil pressure has yet to increase to above 2 bar. Our second 912 (now 250 hrs) is doing exactly the same thing. We have yet to attach a steam powered pressure gauge, but thought I might as well ask the question.

Any help appreciated, Regards Don Cramer.

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Re: 912S Reduced Oil Pressure.

by Roger Lee » 13 years ago

Roger Lee

125 5.11k 4.52k

Hi Don,

First thing is do not add any more shims under the oil pressure spring. You may take your real oil pressure way over the max and not even know. One tattle tail warning sign was you added a shim and saw no change.It should have made a 5-7 psi difference. Your Rotax person there gave you some incomplete info and you may cause harm. Many Rotax oil pressure senders weaken with time and vibration. Very first thing to do is verify whether you really have a low oil pressure or are you getting a false reading. Usually 98% of the time it is a bad reading. Most don't verify the real oil pressure and just throw things at the problem without doing a proper diagnosis. You need to put a mechanical pressure gauge in line with your existing oil pressure line. The cost of materials for a simple 0-100 psi gauge, some 1/16th copper tubing, a tee fitting so you can put your oil pressure sender back in line and some compression fittings is only about $20. I'm willing to bet you don't find you have an oil pressure problem as the Rotax 912 is very reliable and you find it is something else like the pressure sender (#1 problem usually) or even your gauge (not as likely).

I have seen this problem more times than I can count over the years and not once was it a real oil pressure problem, but an accessory problem like the sender or gauge and even bad ground connections.

You can also try these new parts from Rotax. It is a ten minute change and may help as it has others. You may not see a change with these either because if it is a sender issue then these parts won't help, but I would recommend these parts to be changed anyway after the problem is found. These new parts will help steady and possibly raise you pressure a little. Do the in line pressure check no matter what and don't do anything else until it is done. You are only working blind until you know something for sure.
Rotax parts: plug screw 841-983, Spring 838-122, and oil pressure regulator cone 857-230

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

Thank you said by: YEN NIEN YU, Guilherme Tomazini

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Re: 912S Reduced Oil Pressure.

by Bo Lindroth » 13 years ago

Bo Lindroth

0 4 0

Hi Don
Ihad this problem to at 350 hours time. It was the sender. If you buy a VDO sender you get half price.

Bosse

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Re: 912S Reduced Oil Pressure.

by Anders Eriksson » 12 years ago

Anders Eriksson

0 10 0

Hi Roger,

Can you tell me what the size of the thread is?

Could it be 1/8" NPT?

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Re: 912S Reduced Oil Pressure.

by bill martin » 12 years ago

bill martin

10 757 0

Anders,

1/8 npt is correct. If the problem does turn out to be the sender, you can increase their lifespan by mounting them remotely. Mounted to the firewall or frame, they are not subjected to engine vibration.

Bill.

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Re: 912S Reduced Oil Pressure.

by Anders Eriksson » 12 years ago

Anders Eriksson

0 10 0

Bill,

Thats good to hear.

I will buy a standard car sensor and meter, just to check.

Will a standard sensor work with other meters or are they different?

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912S Reduced Oil Pressure.

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