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High oil pressure 912uls

in 912 / 914 Technical Questions 10 years ago
Hi all, a skyranger on the local field is having an issue with high oil pressure. At power it seems ok but at low revs the pressure increases to 80 + psi. Have changed vdo sender unit then tried another gauge.Exchanged pressure regulator ball and spring from another engine Seems to be the same. Has us stumped at the moment. Any ideas.....Thanks.

  • Re: High oil pressure 912uls

    by » 10 years ago

    Hi James,
    Is this a new development?
    Type of oil used and have you installed the new style oil pressure regulator cone and oil plug cap screw and tossed the old ball bearing one? Is there a shim in the old cap screw?
    Have you installed a temporary mechanical gauge inline with the stock one to double check?
    If you haven't done this one I would recommend a second inline gauge to check before you go any further.

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

      
    Report

  • Re: High oil pressure 912uls

    by » 10 years ago

    Hi Roger, thanks for the reply. I believe this is a new development. The oil used is a Shell oil 15w 40. There's a lot of engines using this oil localy with no probs. It is one of the recomended oils.There is no shim used and the new reg has not been fitted. The next check was to use a mechanical gauge........cheers....
      
    Report

  • Re: High oil pressure 912uls

    by » 10 years ago

    Hi James,

    A mechanical gauge at this point is a good idea to rule some items either in or out as the problem.
    Good luck on your trouble shooting.

    Where do you live?

    If you are referring to the Shell VSX4 oil motorcycle oil?
    The better Shell oil Rotax recommends is Aero Shell Sport Plus 4 a 10w-40W semi synthetic which is made in the UK with the Rotax in mind.



    Just an FYI:
    You should not be using a standard car oil as it lacks additives for the gearbox / engine combination. Mainly the ZDDP additive. You want to use a good full or semi synthetic motorcycle oil with the correct additives because our engine like motorcycles share oil from the engine with the gearbox. Car oils don't use ZDDP because they have different engine components and the ZDDP ruins the catalytic converter.

    Here is the Service Instruction for suitable fluids.

    http://legacy.rotaxowner.com/si_tb_info/serviceinfo/si912i001r1.pdf

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

      
    Report

  • Re: High oil pressure 912uls

    by » 10 years ago

    Hi Roger, we are in Australia. Yes the next move is to put on a mechanical gauge. The oil is vsx4. semi synthetic and seems to meet all the specs.
    If the pressure test does tell that the pressure is high, any ideas ? I may not have mentioned that this is at low revs ( around 2000 ) and pressure starts to drop off as revs are increased....cheers....
      
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  • Re: High oil pressure 912uls

    by » 10 years ago

    Hi James,


    If the mechanical gauge shows a normal pressure then I would suspect the ground wire or the oil pressure sender even if reasonably new. Check the ground wire first.
    I do know that a poor ground wire connection can cause a 20+ psi drop in pressure as throttle is advanced. One way to check this is take a wire with alligator clips on the ends and just by-pass the ground wire you have now. Leave the original in place, but hook up the new ground with the clips to a known good ground like the negative on the battery and then ground the sender and or the gauge. This is the first thing I usually check if someone comes in and says his oil pressure goes way down with throttle and then back up to normal at idle.


    It's a cheap, quick and easy way to double check the ground wire and either rule it in or out as the culprit.

    p.s.
    It may be time to put in the new Rotax parts for the oil pressure regulation. New plug screw, new spring and new oil pressure cone and get rid of the old ball bearing.

    p.s.s.
    The mechanical gauge should help with the direction you need to follow so do it and the ground wire check first.

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

      
    Report
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