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O-360 high oil pressure question

MrNomad

Well Known Member
I have 800 hours on my RV9A with a Superior O-360 engine. The engine was new when built, Exxon Elite oil & Champion filter changed every 50 hours, all oil test results are good, oil temps are 165 approx, and it runs perfectly, like a Swiss watch. It's music to my ears.

Over the last few weeks I noticed the oil pressure increased to 90 lbs on my Dynon D180 and this morning (45 degrees F) it went even higher to 93 lbs cold. I reduced rpm once I got to altitude to go thru Tucson airspace but it did not get below 92 lbs. For the last 10 years it usually starts at 88 lbs when cold and never gets to 90 lbs.

After I arrived at my destination and restarted it 30 min later, it was down to 86 lbs all the way home. The Superior SVIOM01 manual states that 115 lbs cold is the max and 95 is normal operating so it remains within limits.

I can adjust the oil pressure regulator "out" to reduce pressure but I have two questions. I would like to know the crush washer size before I remove the regulator and inspect it, and can anyone explain why this is occurring. One friend said that some dirt may be lodged against an internal spring. No one touches this airplane other than me and I am conspicuously careful.

Comments welcome.
 
Check the sensor first. They typically fail by reading high. Sometimes intermittent and sometimes they just drift higher and higher. They just have a diaphragm and spring inside them. The VDO sensors are wearable parts and I would not expect them to go to TBO.

Don't adjust the relief until you confirm good readings. They don't typically drift over time.
Larry
 
Most Lycomings run high pressure when cold - let it settle for a few minutes after start at 1000 rpm, then a couple of bursts to 1500 and back to idle and it should settle. Ours does it all the time.
 
Sensor

I like the idea of replacing the sensor. Makes perfect sense. I also like the idea of inspecting the regulator without adjusting it. Can they accumulate dirt? If you know the crush washer size, please forward.
 
Suggest you leave it alone. No drawbacks to high oil pressure.

Remember the oil pump creates flow, the relief valve and the resistance to flow movement thru the oil galleries create pressure.
 
I like the idea of replacing the sensor. Makes perfect sense. I also like the idea of inspecting the regulator without adjusting it. Can they accumulate dirt? If you know the crush washer size, please forward.

debris can get caught between the ball and the seat, but it results in lower pressure, at least at lower RPMs. Debris can't realistically create a high pressure, in most cases.

Larry
 
Thanks

Crush washer and sender on order. Sender will be replaced first, engine run till hot. That should tell the tale.

If necessary, I will inspect, but NOT adjust the regulator & report back with any discoveries.

Many thanks.
 
I have one in stock in my hangar. You can wander over and get it, just let me know first.

The other thing is to check the Dynon end - I think you might have the old VDO sensor on the D-180 you have. Note this is not the sender on the engine end, but the sensor on the other end of the hose.
 
Sender fixed it

Today I flew with the replacement VDO OIL PRESS SENDER. Under the same conditions the oil pressure dropped from 93 to 82.

Looks like the diaphragm in the old sender was failing.

Thanks folks.
 
I?ve found this discussion too late but I would have suggested checking the pressure with the engine off. Of course it should read very close to zero with the engine not running but my failing sensor would still read 15-25 lbs indefinitely or until I put some hand pressure on the wire terminals. Therefore failing ?high?.

Bevan

Today I flew with the replacement VDO OIL PRESS SENDER. Under the same conditions the oil pressure dropped from 93 to 82.

Looks like the diaphragm in the old sender was failing.

Thanks folks.
 
Interesting

I have found the same -reading 15-23 psi with engine off but only from time to time....the running pressure, previously verified wit a mech gauge, hasn’t moved. I have the new Kav sensors on hand.....
 
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