High Oil Pressure Caused by Bad Filter?

[9GT]

I checked the archives on this and found that most of the threads drift off topic and become argumentative. Here is the problem: On my buddies plane we both built, at the condition inspection last month among the usual, we swapped out the BM EFIS for a Dynon Skyview. Afterwards, the oil pressure was reading 138 psi at run-up. After contacting Dynon, it was suggested the problem may be the oil pressure sensor used for the BM may not be compatible with the Dynon. A new sensor was ordered and installed and we get the same high readings. Pressure readings were verified with a simple analog gauge. The engine is a Superior IO-360 with C/S prop. Superior suggested a possible adjustment is needed in the relief valve. No change when adjusting the pressure screw. They then suggested we remove the pressure relief valve assembly and look for damage or obstruction and run a soft wire down the port hole. Everything seemed good. Reassembled and still reading up to 138 psi. Now we are thinking maybe we got a bad filter and that is causing the high readings since it was changed at the condition inspection and that's when the problem showed up. Any suggestions from the engine guru's out there? We are at our witt's end on this and are awaiting delivery of a new oil filter and case of oil.

[zav6a]

I think most Lycomings require a filter with a built in by-pass. Maybe the new filter lacks it. Hard to believe that the filter media would generate that kind of back pressure in any event.

[az_gila]

Did you take the oil filter mount off in the work you did?

If so, the gasket under it could be intalled incorrectly blocking a port...

[Alan Carroll]

Dan Horton once posted an oil system schematic that showed the pressure sensor being downstream of the oil filter. If this is correct then it doesn't seem likely the filter could be the problem.

How about plugged oil passages near the relief valve?

[RV8iator]

Did you just try another filter?

Cheap and easy to do.

[Tandem46]

Originally Posted by Alan Carroll

Dan Horton once posted an oil system schematic that showed the pressure sensor being downstream of the oil filter

Located here:
http://www.vansairforce.com/communit...flow+schematic

Originally Posted by Alan Carroll

If this is correct then it doesn't seem likely the filter could be the problem

I agree based on location of pressure sensor.

[9GT]

Originally Posted by RV8iator

Did you just try another filter?

Cheap and easy to do.

Its a remote mount Wolfe system mounted on the FW. We are waiting for a new filter and oil. Its going to be our Hail Mary for a simple fix. Superior also said its a long shot but is possible the filter bypass is not functioning correctly. Just wondering if anyone has had this problem crop up. Its so coincidental to the CI and panel change out. The high readings with the new panel really threw us off and set us back several weeks.

[DanH]

Originally Posted by 9GT

Pressure readings were verified with a simple analog gauge.

Hmm, that eliminates stuff like new EMS settings.

Where did you tap the oil system? The usual port on the upper right rear of the accessory case is downstream of the filter, thus filter restriction would not cause a high pressure reading.

[zav6a]

This may or may not be relevant but just in case. During some sort of maintenace activity, a hanger mate had something unknowingly fall into the passage that leads from the pressure relief valve bypass to the crackcase. Enough of a blockage that it over pressured and pushed the gasket out from under the filter.

After a lot of head scratching and advice, he probed the return passage with some doubled up safety wire and found the blockage at the interface to the oil pan.

Any chance of a parallel problem?

[9GT]

Originally Posted by DanH

Hmm, that eliminates stuff like new EMS settings.

Where did you tap the oil system? The usual port on the upper right rear of the accessory case is downstream of the filter, thus filter restriction would not cause a high pressure reading.

We just removed the electronic sender from the firewall mounted manifold and used that port for the analog gauge Dan. Off hand, I do not remember if its pre or post the remote mounted filter. Nothing was changed except the oil pressure sender, EFIS display, and a fresh filter and oil. I talked to my AP/AI when I picked up my log books for my Cessna he annual-ed for me and he is also at a loss but is interested in the filter theory. I am going to ask my buddy to cut open the last filter we removed for the C/I and inspect. Also cut open the filter on there now when the new one comes in. He usually does this but I do not know if he has yet.