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Oil pressure

Tbone

Tbone

Well Known Member
Need help from some of the lycoming guru's. I have a friend that is running an IO360A1A with full inverted system. A few months back the oil pressure would fluctuate from about 70 psi to about 60psi. It only happened when inverted. Now it is getting progressively worse even in normal flight attitude when you drop the wing. Was told that the inverted system was looked over and the guage was replaced but with the same results. I remember in a past post that the adjustable oil pressure "valve" could be wrong in certain lycomings. He had a "shim" adjustable type originally but at some time went with an externally adjustable type. Any ideas?
 
Tbone said:
Need help from some of the lycoming guru's. I have a friend that is running an IO360A1A with full inverted system. A few months back the oil pressure would fluctuate from about 70 psi to about 60psi. It only happened when inverted. Now it is getting progressively worse even in normal flight attitude when you drop the wing. Was told that the inverted system was looked over and the guage was replaced but with the same results. I remember in a past post that the adjustable oil pressure "valve" could be wrong in certain lycomings. He had a "shim" adjustable type originally but at some time went with an externally adjustable type. Any ideas?
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I had slightly different symptoms, but its easy to do, so check you just don't have something hung up on the ball or seat of the oil pressure valve.

Pull it out, clean it, put it back in. You'll need a new crush gasket.
 
Oil Pressure

In addition to cleaning the oil pressure relief valve, the three way valve and "oil pot" in the inverted system should be thoroughly cleaned. That some one "checked them" is not good enough. Both components have ball valves.
A vacuum pad adapter will improve the inverted pressure if the current setup is a tee.
All oil system hoses should be #10, with no sharp curves in the hoses.
Setting the upright cruise oil pressure to at least 85# will greatly improve the chances of the engine making TBO. 85# upright will give 75# inverted.
Google Christen inverted oil systems and Marvel Scott oil pressure information for more.
 
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