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dahugo

Member
Gents, I have about 40 hours on my IO-320D1A in an RV-9. After unpickling we used 6 quarts of 100 wegith mineral oil. Changed at 25 hours with the same, and flew some more with no problems. At take-off with max rpm I get an "oil pressure high" warning on my EFIS/EMS--and the pressure is about 95 or so. Again, within spec and nothing to worry about with a new engine, right?

Well, this morning I get in to fly on a business trip and I get the "oil pressure high" warning at 1600 RPM before I even get to teh 1800 for run-up. I ran the RPM's up a few times more and when the pressure exceeded 100 I took her back to the hangar and shut it down.

So, here's my question. This morning was the first day since the plane has been running that it was below 75 degrees--in fact it was more like 60 this morning. All her other hours have been during sweltering Louisiana summer.

Was the high oil pressure a result of the relatively cool temperature coupled with the 100 weight oil? If I had let it run and "warm up," would the pressure have dropped?

And since our summer is almost over, should I go to a lower weight oil? Again, the engine only has 40 or so hours.
 
What was your oil temp during the run up? Temp makes a big difference in pressure. Try it again but let it warm up to 130 or so.
George
 
oil pressure

Max oil pressure is 115 for 0 320D2J according to the operators handbook. Handbook was last revised many years ago. I think Lyc changed max limit for all the four cyl engines to 115, but I can't find it in writing. Temps between 30-90 degrees F. 40 weight oil is recommended.
 
oil pressure

When Cessna resumed single engine production they moved the oil pressure pickup to the front end of the right oil gallery. So if you are flying one of these Cessnas and the oil pressure reads 90#, the oil pressure is really 100#. The upper limit on these Cessnas was increased to 115#, which is really 125# measured at the old location.

For an in depth explanation of this: airplanebroker.com/MARV.HTM

Bottom line, high oil pressure, within reason, is good for the valves on a Lycoming.
 
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