Low oil pressure in 30 hour engine

[rocketman]

I have a factory rebuild engine in my bravo with a new JPI instrument.  Oil pressure in cruise is typically 55 psi at 2400 rpm 65% power. Sometimes it gets down to 52 psi.  That reading puts the gauge in the yellow.  I have checked the JPI with a calibrated gauge and the JPI is only 2 psi less than the other gauge. So the JPI is accurate enough. The pressure transducer is located above the right mag and not over the right alternator.  Oil temp is stable and fine. Oil level typically 9 quarts. No oil burn. All other engine parameters are normal.

any suggestions? Is this oil pressure normal? What are other bravo pilots experiencing. The engine is under factory warranty. 

Ron Dubin

[mike_elliott]

28 minutes ago, rocketman said:

I have a factory rebuild engine in my bravo with a new JPI instrument.  Oil pressure in cruise is typically 55 psi at 2400 rpm 65% power. Sometimes it gets down to 52 psi.  That reading puts the gauge in the yellow.  I have checked the JPI with a calibrated gauge and the JPI is only 2 psi less than the other gauge. So the JPI is accurate enough. The pressure transducer is located above the right mag and not over the right alternator.  Oil temp is stable and fine. Oil level typically 9 quarts. No oil burn. All other engine parameters are normal.

any suggestions? Is this oil pressure normal? What are other bravo pilots experiencing. The engine is under factory warranty. 

Ron Dubin

How has Lycoming responded now that you have checked it with a calibrated gauge, Ron?

[FoxMike]

After an overhaul the bearings are tight.  In 25 hours or so the bearings wear in and the oil pressure drops some.  An adjustment of the oil pressure should raise the pressure.

[Guest]

If the oil pressure has always been that low, have your maintainer raise it to better than 70 PSI.  If it was higher before and has dropped some investigation is in order.

Clarence

[Bob_Belville]

23 minutes ago, M20Doc said:

If the oil pressure has always been that low, have your maintainer raise it to better than 70 PSI.  If it was higher before and has dropped some investigation is in order.

Clarence

Ron told us it is a factory rebuilt engine. I assume there is no meaningful "before".

[Guest]

17 minutes ago, Bob_Belville said:

Ron told us it is a factory rebuilt engine. I assume there is no meaningful "before".

Someone must have installed it in his plane and ground run it before he flew it? If it was that low from the initial install it was too low.  I doubt that Lycoming sent it out the door at 52-55 PSI.

Clarence

 

[rocketman]

So yes M20Doc Lycomings  test run showed a pressure of 75 psi at 2500 rpm and oil temp of nearly 190 degrees. My "maintainer" did adjust it buy turning it in 1/2 turn and it made no difference. My mechanic does not want to turn it up much more since the test run was 75. Lycoming now says its OK but I cannot run the engine with the needle at the low green going sometimes into the yellow. Now what? I know their is a washer near the oil pressure valve that can be added but again I hesitate to do anything since the pressures were normal at the factory.

[Guest]

11 minutes ago, rocketman said:

So yes M20Doc Lycomings  test run showed a pressure of 75 psi at 2500 rpm and oil temp of nearly 190 degrees. My "maintainer" did adjust it buy turning it in 1/2 turn and it made no difference. My mechanic does not want to turn it up much more since the test run was 75. Lycoming now says its OK but I cannot run the engine with the needle at the low green going sometimes into the yellow. Now what? I know their is a washer near the oil pressure valve that can be added but again I hesitate to do anything since the pressures were normal at the factory.

The oil pressure reading can be different at different pick up locations throughout the engine.  I would ask Lycoming where they take their reading.  

The pick up at the upper right one is the most common, though many are now taken at the front right behind the flywheel.

Having proven that the JPI is accurate I would not hesitate to increase the oil pressure by turning the relief valve more.  2-3 turns may be required to raise it to mid seventies.

Clarence

Edited October 19, 2017 by M20Doc

[N201MKTurbo]

I had my oil pressure suddenly drop like that once. It turned out to be one of the idler gear mounts had come loose and was bleeding oil into the accessory case. I'm not saying that is what it is but it wouldn't hurt to pull the mags and look in there.