Help! Let me tell you about what I did, current status, and what I suspect. 1996 Ford F-250 7.3l diesel 300k miles. Recent purchase. Oil cooler was leaking, so I purchased a new seal kit, oil filter, oil, and everything for a coolant flush. Drained the old oil filter, drained radiator petcock, removed oil cooler assembly. During removal, I noticed a small ball (like a bearing) fall to the ground. I assumed it was from something, but unsure of what. I cleaned up the cooler, changed out the seals, put it back together and reinstalled it. I drained the oil pan, replaced with new oil filter, new oil, distilled water in radiator to flush. Tried to start the truck, no start, no oil pressure it appeared. After trying to crank it a few times, I opened the HPOP plug, and the reservoir was empty.
My best guess is there should be a check valve in the oil cooler rear mount, and thats what the ball fell from. Not sure why i didnt notice a spring or washer fall. The only part I can find to repair this issue is an entire new rear cooler housing, Dorman #904-408; i cannot find the check valve itself, nor do i know if my rear mount is good/damaged to not hold in the check valve any longer.
Can anyone confirm my suspicions? Can I just drain the oil pan into a clean container to reuse the oil? Remove oil filter, remove rear cooler housing, replace with dorman housing, install filter, top off coolant, refill oil in HPOP reservoir and via fill for engine to correct # of quarts?

 

You are on the right track. The earlier 7.3 had the check valve staked in place, later ones had a snap ring to do the job. You should not have to drain the oil from the oil pan, just the filter and what oil is in the cooler. You should be able to reuse the coolant if you can keep it clean.

 

Thank you so much for your help! I just have distilled water in the coolant system as I was planning to flush, so i dont need to keep that. When I take the 3 bolts off the oil cooler rear housing, wont the coolant get into the oil pan? Thats why I mentioned draining the oil into a clean container first.

 

That is a possibility, so if you want to drain and reuse the oil, go ahead.

 

Thank you for your assistance, as you were the only one to offer any. Got the new oil cooler housing which has the check valve held in with the snap ring, and sure enough, the old one was MIA. Reassembled everything and she fired right up.
Then I began my coolant flush. When I took out the thermostat, I dropped one of the housing bolts and the engine gunk has claimed it. Now I cannot finish until i get a replacement bolt. Story of my life.

 

Man wish I would of read this post when you posted it, I would advise against using those oil cooler seals, only buy OEM as other seals tend to fail quick.

 

They are Fel-Pro, had good reviews online and as a brand felpro has always been good quality. After doing this oil cooler twice now, when it does need to be changed again, I could probably do the job in 30 mins. Its actually not that bad