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prkaye

Well Known Member
I've been paying a bit more attention to my oil pressure lately. It's always been well within my green arc, but I'm wondering if it's at tad high. A few questions about high oil pressure:

1) What are the dangers of running with high oil pressure (say up to 84psi during a runup to 1700RPM, and down to about 76 at idle, in cold weather)?

2) Can high oil pressure cause more oil to get blown out through the breather tube? After an oil change, I ran the engine with the cowl off for about 5 minutes and then looked around for leaks. I found a blob of fresh oil under the belly roughly in line with the breather tube.

3) How sensitive are oil pressure readings to the temperature of the oil?
 
In general, the colder the oil, the higher pressure you will be reading. As the oil warms up and thins out, the pressure reading will go down. Not knowing your engine, I would think 84 PSI is within the normal range. Mine (IO-360) reads around 79 and on cold days it is around 82 PSI but I haven't paid much attention to it since my alarm does not go on. I believe, if I am not mistaking, the high setting is set to 90 PSI.
 
Oil pressure should not have an effect on breather tube spewage. Ring blowby, sump level & negative G's are what will. Pretty sure.
 
I am a proponent of running high oil pressures, for numerous reasons. On a cold day my oil pressures run about 100-105psi, with no ill effects.
 
Oil Pressures

This is what Lycoming lists as the O-320 oil pressure limits:

(Normal operation) Minimum 55 p.s.i. - Maximum 95 p.s.i.
(Idling) 25 p.s.i.
(Starting and warm-up) Maximum 115 p.s.i.

Your numbers seem normal. Good luck, Russ
 
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