Engine oil cooler overheating, 88 Suburban

[sandybottom]

Originally Posted by rickpilgrim

First- are your cooler fins clean and not obstructed with dirt/dust/debris of any kind? Secondly it is possible that the cooler internal passages are partially to completely plugged which would put the system into bypass mode where the oil just circulates around the filter housing and back to the engine.
Personally I would get a new cooler for a 3500 truck(slightly larger) installed.
Suburbans are heavy, your small block works hard and an oil temp of 300 or so would not surprise me as our dually with its 427 TB has 10 qts oil and a remote filter and on a hot day with 180 thermostats we see 220-230 oil temp when towing.
Make sure your fan clutch is good, clean radiator so you have ample air flow.

Thanks rickpilgrim, the clutch fan was my first suspect but before I dug into it I wanted to be sure I didn't overlook anything. I'll follow up on the fix!