Oil Pressure Rise - TSIO 360-LB

[FlyWalt]

Good morning,

On a recent flight I noticed the oil pressure had risen to just below the high red line. I reduced power and she moved down a bit but not very far. On later flights, I have not seen this issue return.

What would be the cause of something like this? My fear is some sort of contamination. The aircraft has sat for as long as six weeks between flights. Although, typical is more like every two weeks.

Regards,

Walt

[A64Pilot]

I bet it’s the gauge, I’d temporarily install a direct reading gauge and verify that the engine oil pressure is correct.

‘Don’t do anything to the engine until your sure the oil pressure is actually high.

[FlyWalt]

Well I am due for an oil change so it is a good opportunity to look more closely at the filter.

[jaylw314]

It's not just while the oil's cold, right?

[81X]

What @A64Pilot said.  That’s not normal for an LB with the oil at that temperature in your photo. Likely/hopefully a gauge.
 

I’ve been told that the oil pressure pickup is pretty much at the end of the line on these engines- partly why it reads really low at idle when hot so this doesn’t seem normal at all.  This would also make a blockage induced spike less likely again hopefully pointing towards the gauge.  
 

Working with your A&P to put a known working pressure gauge on the engine as soon as possible will help you diagnose.   

[201Steve]

Walt if you’re going to do an oil change, I’ve got some Blackstone oil jars in the hangar. I would like to know if there are any funky spikes from the sample in the event it’s not a reproduceable one off phenomena. 

[RJBrown]

Every engine has a oil pressure relief valve. A simple poppet and spring. As pressure rises, especially if oil is too cold, the spring compressed and it opens a hole to dump oil pressure. I’ve seen them stick cold and split a oil filter from over pressure, in cars. If they stick open you won’t get enough oil pressure hot and could starve an engine.

Not something to ignore, this is a picture of your valve.

not sure how accessible it is but removal and cleaning could not hurt.

Edited March 13, 2021 by RJBrown

[FlyWalt]

Good Morning All,

Couldn't sleep as this is bugging me. RJBrown, thank you for that photo. I will be pulling and cleaning that valve during the oil change. Steven, thank you for the offer. I will stop by your office on Monday.

Fly Safe,
Walt

[carusoam]

That device is often called the OilP regulator...

Spring loaded, and adjustable... often set at the factory and never touched for decades...

If it is really the issue of the oilP being high... it is a pretty easy access kind of thing...

Like anything mechanical... it can mis-behave....

Gauges are pretty easy to test... too.  Working/not working...

Haven’t seen much about OilP sensors... around here...

That is probably the most suspect...

• sensor
• gauge
• actual regulator
• gauge/panel ground

List of things that could cause an OilP reading to go astray...

Best regards,

-a-

[A64Pilot]

Trust me, remove your pressure transducer and install an inexpensive automotive type of direct reading pressure gauge, use it to verify your pressure.

‘A stuck closed high pressure relief valve is extremely unlikely, and if it were stuck closed, your pressure would skyrocket on initial takeoff when the oil is cold and thick, not in cruise when it’s hot like in your photo.

Don’t go mucking with your engine and adjusting oil pressure to make a bad gauge read good, verify that gauge before you touch your engine, you don’t have to fly or even taxi to verify the gauge.

Too high an oil pressure is as rare in an engine with hot oil as Unicorns are, not impossible but very unlikely.

‘The best way to test the gauges with what’s called a dead weight tester, that when the transducer is removed from the engine and installed into a small calibrated pressure pump and then the mechanic can crank up the pressure slowly and compare your gauge against a calibrated one. Many smaller mechanic shops won’t have one, but a good engine shop certainly should.

‘That’s the best way

[carusoam]

For an interesting thread... about OilP and IO360s...

I was hoping to find a pic of what the OilP gauge looked like... no luck...

-a-