High Oil Pressure on E2B O-320

[Tom McCutcheon]

I started getting a high oil pressure reading (150 - 200 cold) 100 hot. I put a test guage on it and it was a bit lower but near these other readings. I then took the spring and ball out of the pressure regulator and the pressure was about 100. This is an E2B O-320 converted to 160 HP. Any suggestions as to what else I should look at? Or, am I looking at a complete tear down? Any help is appreciated.

Tom McCutcheon

[OceanBob]

Was the oil pressure ever a normal 85PSI at power and 25PSI at idle?

What grade of oil are you running?

Do you have an oil cooler?

How many hours on the engine since overhaul or conversion?

Where did you hook in the test gauge in the system?

Thanks
Bob

[Tom McCutcheon]

Thanks Bob,

Was the oil pressure ever a normal 85PSI at power and 25PSI at idle?
ANSWER: Yes, the pressure used to be about 90 and would drop to about 40 at idle.

What grade of oil are you running?
ANSWER: I just put on new cylinders and so I'm running Aeroshell 100W Mineral oil. I have been using Exxon Elite. The oil pressure went up before I put the new cylinders on but I thought it was just the guage.

Do you have an oil cooler?
ANSWER: Yes, I have an oil cooler.

How many hours on the engine since overhaul or conversion?
ANSWER: Based on info at purchase, the engine has about 675 hours.

Where did you hook in the test gauge in the system?
ANSWER: I disconnected the panel guage and hooked up the test guage to the same port that the panel guage is normally connected to.

Thanks
Tom

[Kent Ashton]

Did you put a direct reading _mechanical_ gauge on it? I have had a high OP reading, fretted about it for weeks and finally determined it was a bad sender. I will go so far as to say high OP is usually the sender, the gauge or electrical interference in a non-shielded wire from the sender to gauge.

The OP system is stone simple: the OP relief ball moves against a spring to normalize pressure. The only thing that can make the OP go high is a jammed relief ball or cold oil, AFAIK. Even if there was debris in the OP passages downstream of the relief point, the ball would still relieve to give a normal pressure at the sender port.

BTW, I have also had low OP caused by a piece of plastic (oil container ring?) jamming the relief ball open. That was real. But high OP, it almost can't happen at normal temperatures.
-Kent

[Tom McCutcheon]

I have found the problem. None of you got it though. The problem is that there is a screen in the vernatherm housing. In order to inspect and clean it (every 25 hours) you have to remove the vernatherm housing. I hadn't. To compound the problem the builder took the oil pressure from the accessory case. It is between the pump and the screen in the vernatherm. Under this scanerio, when the screen begins to become plugged the pressure goes up. Had the pressure been taken from where it should be taken (right rear behind the pressure relief unit) the pressure would have shown low.

To answer Kent's post, yes, I used a mechanical test gauge. Also my instrument gauage is mechanical and they both read nearly the same.

The screen has now been cleaned from the sludge (no metalic material) And all pressures are normal.

OK that fixed, I want to replace the vernatherm housing with a oil filter adaptor. For an RV-4 with an O-320 which one work best (space & access).