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  • Re: Problem purging 912UL oil system

    by » 8 years ago


    Gordon,

    You did it correctly.
    You just missed reading the details.

    In the Installation Manual, Section 79-00-00, (Sub-Part 3.3)Purging Directions...

    Step 5 Allows optionally removing the plugs for easier rotation.
    Step 7 Indicates that 5.8 psi is sufficient. More is Not necessarily better.
    The pressure is there to prime the lines up to the oil pump, nothing more. If the Oil moves, It's enough!
    5 psi is more than enough pressure as long as your Oil Cooler is less than 10 feet ABOVE the Oil Tank.
    Steps 7&8 Instruct to you to turn the engine for the first indication of oil pressure.
    You saw 3+ bar. Way more than necessary! You're Done!

    Step 9 Instructs to re-attach the hoses.
    Step 10 Instructs refitting the Spark plugs. This is where you went astray.
    Step 11 Instructs hand turning the engine to return the Oil to the tank. (Plugs In!)

    If you have done this 3 times, you may have a liter of oil in the crankcase.
    If you have been topping up the oil tank, you may see it overflow when all that oil returns.
    Be prepared to drain some oil if needed.

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


    Thank you said by: Rob Seaton, Gordon Grant

  • Re: Problem purging 912UL oil system

    by » 8 years ago


    Thanks for the information, I nearly got it right first time! Using the guidance from Bud and yourself I got the system properly pressurised and purged successfully. No problems with the tappets either so I was good to go!

  • Re: Problem purging 912UL oil system

    by » 8 years ago


    Getting ready for my first start and did a purge of the oil system at the weekend, but my battery died just as we started so no panel on which to read the pressure. Figured we would go on anyway until some oil came out of the return line into the bucket but even after 60 turns or so, all we ever got with a steady slow drip.

    I'm convinced the line is pressured, and we'll have the battery charged for next weekend so we will see the reading, but the guy who was helping me was sure we should see running oil so he isn't convinced.

    So just curious whether oil should run out of the line when purged or not.

  • Re: Problem purging 912UL oil system

    by » 6 weeks ago


    Roger Lee wrote:
    You can purge with the plugs in or out. I've seen it done both ways. So long as the return hose is hanging in the downward position oil should drool out. If the plugs are in it will pressure the oil out the case. I think the problem is you said you're using a foot pump? If so you need to use a compressor and try 10 psi with some volume vs your 5 psi. Volume here is more a key than pressure by itself. You can use between 5-15 psi. If you leave the plugs in you rotate the prop slower because of the pressure in the cylinders. If they are out I'll rotate at a rate of 90 revolutions per minute. Then since I'm old I call 911 and get some Oxygen before I rotate one more minute. :P :lol:
    The oil pump is a positive pressure rotary pump and so long as something is pushing oil in (your air pressure) and the carnk is turning (rotating the prop) then oil gets moved through the system.
    I usually see 50-55 psi on the oil pressure guage in the cockpit. Since I'm paranoid of having a bad purge I do a purge twice. Cheap insurance for just 1-2 minutes of work. Sometimes oil comes out and sometimes not, but it has always been good. Check your tappets under the valve cover like it shows in the video. If you do this purge a couple of times and get no oil then start the engine normally. You should have oil pressure immediately. Let it run a few minutes then shut it down and check the oil level.

    p.s.
    When you do a purge have a little extra oil in the tank so as the oil fills the hoses and the like the oil level in the tank won't get too low and possibly inject air.

    Roger can you clarify which steps of the purge you repeat a second time? I’m guessing not the valve tappet check and just the pressurization of the oil? Thanks as always 


  • Re: Problem purging 912UL oil system

    by » 6 weeks ago


    I just spun the prop 80-90 fast revolutions two seperate times. So I spin it 80-90 revolutions in about 90 seconds or so. Then I turn off the air pressure and raise the hose up so not to lose any oil. After a 1-2 minute break I do it all over again. So I have rotated the prop 160 - 180 revolutions which only took a few minutes. Since I started doing this 20 years ago I have never had a soft valve and as you spin the prop I can see 50-55 oil pressure during the revolutions.

    It seems to work well.


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


    Thank you said by: Nicholas Wilcox

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