I have a 915is with 198 hours. On last couple flights it seems a little slow on building oil pressure and then runs a little erratic at idle and rpm’s of 2000 to 2500… (20 -27psi). If I rev it up it will climb into the green (3000+ rpm’s) in cruise it is running about 5 pounds less than its normal 43 pounds. I have just received and analog pressure gauge,but I’m not feeling that it is a sending sensor issue. 
I change oil every 25 hours, and my fuel use is almost exactly 70% unleaded and 30% avgas. I just changed oil and filter with no effect on this issue.

thanks for any thoughts on this


  • Re: Oil pressure

    by » one year ago

    Hello Gary

    Seems nobody wants to tackle this one.  From what I know the oil pumps on the type 915 (912iS also) have a completely different pressure relief system from the older 912 and 914 engines.  They can get very small bits stuck on the top of the regulator piston that might lead to some erratic oil pressures (leading to lower pressures) 

    remove your safety wire and take off the pressure regulator.  The piston has a flat top, the seat inside the housing is also flat and check to be sure that there is no contamination between the 2 parts.  This is just a check and if you do find something you need to know what it might be to determine where it came from. 


    36670_2_915 oil pump regulator.jpg (You do not have access to download this file.)

  • Re: Oil pressure

    by » 12 months ago

    Thank you, I got away for a while. The problem was a hair line crack in the very highest point of the oil suction side (metal tube) just before the oil pump so it never leaked any oil, and wasn’t a suspected part. I found it by pressurizing the oil system and spinning the propeller by hand… the the crack leaked oil.

    thank you sincerely Gary 

    Thank you said by: Ken Ryan

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