wondering oil pressure

[Alaskamech]

I have an 0-320 that has been overhauled 200 hrs ago and the oil pressure has started to wonder. it will run at 70 for a while then just drop to 55 then back to 70. sometimes it will go the entire flight at 70 other times it starts after a short time in flight???
I have checked the pressure relief ball and spring and they look ok, just to check to see if it is indication i have two oil pressure gages and have attached one to the front oil gallery and still have the other is the back, no joy it is the pressure changing. no one i talk to has any ideas. I'm open to any ideas before i rip in to the engine.
thanks for any ideas in advance... Frustrated...

 

[akflyer]

Mine did that and I replaced the spring and ball even though they "looked" fine. It has been rock solid ever since.

 

[Gilbert Pierce]

What oil pressure gauge are you using?

 

[Stephen]

I've had to clean out under the relief valve to get my pressure back up.

 

[Steve Pierce]

Sounds like the old style oil pressure relief valve and the case was upgraded at overhaul per the service instruction.

https://www.shortwingpipers.org/forum/showthread.php?8603-Lycoming-relief-valve-sleeve

https://www.shortwingpipers.org/forum/showthread.php?12387-Oil-pressure-fluctuation-after-overhaul

 

[Alaskamech]

Thank you Steve and all, great help. yes when i looked at the ball and spring this last time there was no cage. I'm going to order the adjustable cap and a new ball/spring just in case. i printed the SI and will change the parts when they get here and let y'all know how it goes ..

Terry.

Gilbert, both gages are electronic. Thanks all.

 

[Gilbert Pierce]

I had the same problem with an EI electronic gage. It turned out to be corrosion in the connectors between the pressure transducer and the gauge. This voltages are very small so it doesn’t take much resistance to cause an erratic reading.
EI has come up with a radically different connector to solve the problem they were seeing.

 

[Alaskamech]

I had the same problem with an EI electronic gage. It turned out to be corrosion in the connectors between the pressure transducer and the gauge. This voltages are very small so it doesn’t take much resistance to cause an erratic reading.
EI has come up with a radically different connector to solve the problem they were seeing.

Thank you Gilbert, i replaced the original mechanical with a new electrical one as the temp part of the gage gave up/leaking, and the other is a new JPI 830 and am picking up the pressure from two different places both showing the same pressure fluxuation. I have ordered the new adjustable style cap, ball/spring we will see, the cage was removed at case overhaul. it only makes since what others are saying and it has fixed there problem soooo I'm am hopeful this will do it.

Terry

 

[Alaskamech]

well after reading the SI i ordered a new adjustable cap and new ball. installed them and no more problem. the basket had been removed and i had no idea of the change. Thank all of you for your help on this.

Terry

 

[Steve Pierce]

Awesome, I know that has to be a good feeling.