Hi All,

I have a Searey with a 914 on it. I purchased it last year. When I bought the aircraft, during the pretty the mechanic demonstrated an oil change. Remove the oil tank, drain it, clean it, replace it. Remove filter, fill new filter with oil, install filter, check magnetic plug. Burp oil. Start engine check for leaks.

I was doing my 4th oil change on the plane the other day and someone mentioned I was doing it wrong, and not purging the system afterwards. I had though I was purging the system by hand-propping until gurgle, and minimizing air in the filter/lines by leaving them upright so they don't leak and filling the filter.

So I googled and realized I'm wrong, and I've been doing it wrong. I'm concerned now that I've injected air into a lifter and/or damaged a valve or something. 

Is it advisable or possible to do a lifter squish check now to make sure they are all good? Or realistically, with 5hrs of operation since my last oil change - is it a moot point? I've now read and watched the Rotax videos on the subject, and they mention checking the lifters afterwards to 15lbs for 3 seconds. And also running the engine at 3500rpm for an extended period to eliminate air. Well. it's been run at 5200rpm for an extended period.... so...

I am wondering if there's a way I can inspect for any damage, and make sure the lifters are hydraulically fine.

Thank you,

  • Re: 914 Oil Purge Check

    by » 11 months ago


    Thank you for raising this concern. We have taken note of the issue regarding the improper purging of air from the oil system, which can lead to flat lifters and subsequent hammering on the valve train. In severe cases, this can result in excessive stress on the valve spring retainers, leading to cracks and even valve drop into the combustion chamber, causing a catastrophic engine failure. The occurrence of this failure can vary, with instances observed as early as 7 hours and as late as 1900 hours of engine operation. It is crucial to remain vigilant and ensure that proper procedures are consistently followed throughout the engine's lifespan to mitigate such risks.

    To address this issue, it is important to adhere to the correct procedures for purging air from the oil system. we recommend referring to Service Instruction SI-914-020R4, which provides instructions on what needs to be inspected if the oil purge was not performed correctly. You can access the service instruction using the following link: [Service Instruction Link - https://legacy.rotaxowner.com/si_tb_info/serviceinfo/si-916i-003-r1.pdf]

    Additionally, we would like to share some helpful video links that provide guidance on various procedures for the Rotax 914 engine:

    1. Proper purge procedure for the Rotax 914 engine: [Video Link 1 - https://www.rotax-owner.com/en/videos-topmenu/free-videos/685]
    2. Proper oil change procedure for the Rotax 914 engine: [Video Link 2 - https://www.rotax-owner.com/en/videos-topmenu/expanded-video-instructions/39-exp-si-27-010]
    3. Proper oil level check procedure: [Video Link 3 - https://www.rotax-owner.com/en/videos-topmenu/expanded-video-instructions/36-exp-si-27-1997]


    We encourage everyone to watch these videos and ensure that the procedures are followed correctly to maintain optimal performance and longevity of your Rotax 914 engine.

    Should you have any further questions or require additional assistance, please do not hesitate to reach out or contact your local Rotax distributor, dealer, or repair station. You can find their contact information using the following link: [Rotax Dealer Locator - https://dealerlocator.flyrotax.com/]

  • Re: 914 Oil Purge Check

    by » 11 months ago

    Calm down.  No need to get excited.
    Do not confuse Burping with Purging.
    BURPING pushes the residue Oil in the crankcase back into the Oil Tank to produce a valid Oil Level Check.
    PURGING fills the Oil lines Between the Oil Tank and the Oil Pump including the Oil Cooler.
    If you did NOT Drain the Oil Cooler and Oil Lines going to the Oil Pump,  There will be No Need to PURGE the Oil Line.
    You may have tried to fill the Oil Filter, but there was still a lot of air in it.  No foul!

    After an Oil Change, if you want to get Anal about it (Not a Bad Thing); Crank the starter with the Mags OFF until you see Oil Pressure.
    Once you have confirmed Oil Pressure, perform a normal start and be on your way.
    If you see Oil Pressure within 5 Seconds (Usually much less) after starting; all is good.

    A stuck lifter is a very rare, first start of a brand-new engine issue.
    If a brand-new lifter happens to completely drain and become bone dry, it may not self-prime.
    This might also happen if the engine is not operated for a few years.
    A little Air is always present in the Oil during normal operations and the Lifters will purge any small bubbles as part of the nature of their normal operation.
    A lifter will suck in a tiny amount of Oil (and Air if present) every time the valve closes and bleed out a tiny amount of Oil and any air that may have been ingested when the valve next Opens a few milliseconds later. 
    This happens thousands of times each minute. 
    That's how it works.

    Unless you are draining the Oil Pump/Cooler Lines,  you are doing it correctly.  No PURGE Needed.

    Bill Hertzel
    Rotax 912is
    North Ridgeville, OH, USA
    Clicking the "Thank You" is Always Appreciated by Everyone.

  • Re: 914 Oil Purge Check

    by » 11 months ago

    Let's clarify the procedure:

    Did you remove the oil tank and clean it each time you performed an oil change?

    According to section 13.7 of the manual, purging the oil system is necessary in the following cases:

    • After reinstallation, such as after an overhaul.
    • After maintenance work that involved opening and emptying the lubrication system. This includes the removal and cleaning of the oil tank.

  • Re: 914 Oil Purge Check

    by » 11 months ago

    If you pull the in and out oil fittings off the top of the oil tank and keep them up in the air so no oil drains out then you lose no more oil if you remove the tank than just doing a normal oil change. Oil in these two fittings drain out of each fitting when doing a normal oil change and it is no different if you pull the tank to clean it IFyou keep the fittings up higher than the tank because no oil will come out. So you do not need to do a full purge just rotate the prop and vent. Also always pre-fill the oil filter.

    If you don't  believe there is no oil in the fittings when you do a normal oil change just take each one off and see if it drains. So long as it is held up no oil will drain other than what drains during a normal oil change.

    Rotax must think people lower the oil fittings and allow all the oil to drain when you remove the tank.. 

    Venting and purging are two different things. When I remove these two hose off the top of the oil tank I just place a rubber stopper in each one and you never lose any oil.

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

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