Oil Pressure Adjustment (io-360-c)
 

The oil pressure on my front engine was 20psi lower than rear engine on same settings.

Location of oil pressure relief valve is on pilot side > accessory case > adjacent to alternator. It has safety wire and is a 1 1/8” socket fitting.

2 ways to adjust

1: Older engine were not adjustable. There is only a long spring and it needs to be replaced to get the proper resistance required. With that said, When i removed mine there was a “hack” where the spring meets the cap, someone before my ownership placed 3 washers between the cap and spring. This added the needed resistance to create proper pressure. Im guessing this is not the first time pressure was low.

2: TCM makes a replacement adjustable oil relief valve. The spruce sells it and as of today the parts total about $600. Ive attached photos of the parts diagram.

https://ibb.co/gMYKhsF
https://ibb.co/gtw73v7
https://ibb.co/H2LgNyx

You raise a great point about troubleshooting low oil pressure! Too many engines have been condemned that only needed this oil pressure adjustment. My friend's A&P wanted to do an overhaul on his O-320 due to low oil pressure at idle. I told him to have the A&P adjust the oil pressure before tearing down the motor. Sure enough he got the pressure up to acceptable levels and the plane/engine is still flying today.

Cessna ME75-27 covers this kit
Continental M75-10

Kit for TSIO360 EQ6516
IO360. EQ6518

I purchased my kit EQ6516 from Preferred last month NOS for 385 don’t know if they have another.

Dan