Confusing Oil Pressure / Temp issue

[amexbmorgan]

Anyone chased this down before?

IO306C non Turbo

Oil pressure is fine cold. Once Temp rises, oil pressure falls off, just out of lower green. When in this mode, oil temp never gets to 180 in cruise. But can get to 180 after flying and taxing back.

So, I would say oil pressure stabilizes around 25psi, oil temp around 120 in cruise.

I have checked and replace the oil pressure relief springs, plunger, valve seat, etc.

Went to a single weight oil. One flight it was fine. Thought that was the issue. Then next two flights stabilized at 25 psi and 120 temp again. Outside temp didn't make any difference. Flew when it was 100 and once when 70 outside temp.

Before I assume the pump, which could be, I will be checking the gages for accuracy. Both pressure and temp.

This is a new to me engine, so unfortunately I don't have history.

Other thoughts are internal gasket leak. Would an internal accessory case gasket leak do this as well? Basically oil pump pulling air?

What is confusing to me is low oil pressure and low oil temp. If I had a bearing issue, wouldn't the oil temps be rising?

Thanks for any insight!

[RandyArizona]

>>>>>I will be checking the gages for accuracy. Both pressure and temp.<<<

Easy cheap stuff first.

Service manual chapter / paragraph , 10-76
Gives you steps for low press and temp.
Is it complete? Not really, so systems knowledge comes into play.
It is a good start though.

[Jhogan0101]

Check out aerospace logic. I swapped out all of my gauges for theirs. Maybe do a couple at a time. Those numbers seem very low to me (337B)

https://imgur.com/a/RVAJmDh

https://imgur.com/a/o23vT2J

[Joes]

Switch the temperature leads for the engines on the gage cluster. It's a easy way to see if the troubled engine temp is higher than indicated, that's a easy start.
Joes

[amexbmorgan]

Thanks All

Joes - How do you do that? I have 337D, I thought it's a "printed" circuit board with a connection plug on the left lower side of the board.

I haven't got back there to see if it the temp gauges are connected differently.

Pretty straight forward on the oil pressure swap though. Discovered a low indicating oil pressure gauge by swapping the oil pressure lines.

Thanks,

Bryan

[Joes]

It's a Card Edge Connector Housing that slips over the circuit board flat. The card edge connector is a part number A-MP 582376-9 69-49 and uses pin number 530004-7 TERM EDGE DUOTYNE 22-26AWG CRIMP. I'm told that a Gottlieb Pinball Edge Connector Pin Removal tool will help swap the pins once they have been located.
I have a extra Cessna 337 Instrument Gauge Cluster PN# C669506-0202 Fuel Engine Cluster Gauge if you would like to swap it out without all the pin switching.
Joes

[amexbmorgan]

Ok- I know the oil pressure issue is not the gauge. Swapping the gauge confirmed same low readings.

I also was able to get the cold oil pressure adjusted to the top of green, however, it took almost all of the adjustment screw to get there. That is not right, I'm thinking to myself.

Is there anyone out there who is willing to have a call to talk things through with me about my issue.

I know I have an oil pressure issue. However, I can't determine, if it is the pump not producing or there is an internal leak somewhere downstream.

I think I understand how the governor sends oil to the prop (Full Feather governor), but want to clarify what I know before I start taking parts off the engine.

PM me if you have time for a call.

Thanks,

Bryan

[Jhogan0101]

There is a spring, you can put washers in the shim/adjust the pressure. Best have someone thats done before with you. Not something you want to screw up….

[kbecker]

I just went through this on my annual inspection yesterday. I was running 30 psi in cruise and wanted it around 40.

I purchased the replacement springs though Spruce, looking up the numbers in the IO360 IPC. The new springs were slightly shorter than the old ones, but made of larger guage coil.

My rear engine originally had the pressure adjustment just about all the way in, and changing the spring, which is stiffer, allowed us to adjust the pressure in the midrange.

The front engine adjustment was about 1/2 of the way in--changing the spring made the pressure too high, even at the lowest setting. So we replaced the front spring with the original one and turned it in somewhat to dial that pressure in.

[amexbmorgan]

Kbecker - Do you have a part number? I replaced my spring with one listed in the IPC, but didn't notice any difference other than color. New one was blue.

Thanks,

Bryan

PS. My new one was part number: 637083

[kbecker]

I’ll look it up tomorrow when I have access to my laptop computer

[kbecker]

Mfr part 627458

[amexbmorgan]

Kbecker -

Interesting! Thanks!