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A few days ago I noticed that during startup ( around 60 F ) my oil pressure went up to 90 or so PSI .. it seemed to vary with throttle settings ( higher RPM = higher pressure ).

Within 10-20 seconds it came down to what I consider normal range for my engine ( < 60 PSI ) and then was fine going forward. I stopped the engine, checked everything and could find anything and on the next startup and subsequent flight it was just fine ( upper 30s low 40s)

Well, today it happened again, this time went up above 100 and it varied with engine power but in the opposite direction ( more power = lower pressure ) - again 10 seconds later everything went back to normal ( it came down rather suddenly , within 1-2 seconds )

It seems that this only happens if the oil is cold , once it warms up everything looks good..

A few years back I had some issues with my sender with oil pressure going high but it was during flight only and it would come and go - basically different symptoms so I am wondering if this is another issue with the VDO sender or what ...

I figure the best way to check would be to plug a mechanical gauge and see what is going on - is there anything especial to this process ?.. do I just unscrew the sender and replace it with 1/8 NPT gauge fitting ?

Anything other to worry about when testing with the mechanical gauge?

Thanks

  • Re: High oil pressure on startup

    by » 3 years ago


    Until the oil is warmed up to 50C (122F) you should not rev the engine past about 2500.  Until then it will be too viscous for higher revs. If you do rev higher, your oil pressure is of course going to go up, probably higher than you want it; it will start to bypass the filter, etc.  If you went up over 100psi for very long, I would start to worry, as 100 (102 max, per the manual) is the absolute top end of the pressure range.  I wonder if, when you went over 100, the oil started to bypass the filter, bringing the pressure back down quickly after those 1-2 seconds.  Having pressure that then decreases with higher revs is definitely not a good thing, I would say.

    What oil are you using, by the way?


  • Re: High oil pressure on startup

    by » 3 years ago


    Well, what I mean to write is that reving the engine meant going between 2000-2300 during warmup, just as I have done every time I start the engine in the last 500 hours or so.

    In other words, I have been doing the same thing as always but this time PSI went up to 100 for a 10 or so seconds and then within span of 1-2 seconds went down to my usual range.

    I have been using the same Aeroshell Sport Plus 4 oil for all of my 500 hours with this plane.

    I am gonna try to plug a mechanical gauge and see if I can replicate the same spike at the start...

     


  • Re: High oil pressure on startup

    by » 3 years ago


    Be sure you match the threads on Mech Gauge with the Sender.
    Some Oil Pumps are 1/8 MPT (~3/8x27 Tapered Threads ) and some are M10x1 (Straight Threads)
    They are so similar that they will start to thread a few turns on each other before cross-threading!   (Roughly  0.405 x 27 vs. 0.394 x 25).
    Don't be THAT Guy!

    1/8 Pipe to M10 Adapters are available at any decent Auto Parts store, Amazon, eBay, etc.


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


  • Re: High oil pressure on startup

    by » 3 years ago


    I am pretty sure my engine uses M10 given that is from 2012 but I will double check.

    Thanks for the reminder.

     


  • Re: High oil pressure on startup

    by » 3 years ago


    One more question …assuming this is metric, would this sender be appropriate replacement ?

    https://www.summitracing.com/parts/vdo-360023


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