I need some engine help with my 1987 F350 with a 6.9.



My oil cooler had a pin hole leak I was going through way more oil than I cared to so I replaced it with a new OEM one, new gaskets, and new o-rings. When I was putting it in I sliced one of the o-rings and obviously had the oil and coolant mix. I immediately new something was wrong as there was an odd squishing noise coming from the front left of the motor near cylinder 1. I took the oil cooler out again and fixed the o-ring and everything seemed to be fine aside from the squishing noise was still there. I ran the truck for a while with new oil and filter and distilled water with Cascade dish detergent to clean the cooling system. I flushed the system multiple times and finally it was running totally clean. The coolant was clear as was the oil. The truck was also running fine (the odd squish noise was still there), but it had no noticeable loss of power no odd smells, exhaust was normal etc. Since freezing temps were coming and my garage is only heated when I have the wood stove going I drained the cooling system I still had distilled water in it from flushing and left the drain plug out. Again clean as a whistle.

Since the problem of oil in the coolant seemed to be resolved I turned to fixing the squishing noise. Cylinder 1 was not firing, I could tell because the exhaust manifold didn’t heat up directly below that cylinder. I wasn’t sure if the noise was a collapsed lifter or a dry cylinder (the plastic fitting on top of the injector was leaking quite a bit). Since the glow plugs needed replacing I decided to do a compression test at the same time to determine whether or not the piston in cylinder one was even moving. I took all my glow plugs out (they all came out totally intact), disconnected the injection pump and disconnected the injector lines from the injectors to make accessing the glow plugs and compression adaptor easier. This is where everything went **** up. I jumped the solenoid on the fender wall to spin the starter for 3-5 compression strokes so that I could watch the gauge starting at cylinder 1. The pressure went up to 350 but leaked down quickly. I did cylinders 2 and 3 next. Same result up to 350 but leaked down rather quickly. I then noticed that there was oil pouring out of the bottom of my radiator from the drain plug and I mean pouring. I disconnected the lower radiator hose and continued to test the rest of the cylinders with this result:
#1 350 psi leaked out
#2 350 psi leaked out
#3 350 psi leaked out
#4 200 psi leaked out
#5 350 psi held
#6 250 psi leaked out
#7 350 psi held
#8 350 psi leaked out


Oil continued to come out throughout the testing.


I had started the truck 10 days prior to this to let a friend hear the squishing noise and there was no oil coming from the radiator. The old glow plugs were still in but not connected to the harness. Basically just dummy plugs since they didn't work anyway.


My question is how can removing the glow plugs all of a sudden cause the oil to get back into the cooling system and how should I proceed in trying to fix the issue? I also assume that since cylinder 1 developed compression the lifters are working.


The truck supposedly has 170000 miles on it. I am the third owner. The original owner had it for 20 years and plowed with it so I am skeptical that the odometer has only rolled over once but have no way of knowing.

Thanks in advance for the help and sorry the post is so long but I wanted to get all the details in.

 

I'm not going to get into the rest of the issues yet, but this indicates a problem with your compression tester. See, compression tester is supposed to have a check-valve in it(usually a schraeder valve right at the end of the hose) which only allows air in, but not back out. You the press the button to empty the pressure.
The 350 PSI you see on the gauge is the /peak/ pressure; as soon as the cylinder turns even a couple degrees past TDC, the pressure will drop. And even if not, the pressure will quickly leak past the rings through the ring-gaps; that's just how engines work.
So I'd check to make sure your tester is working right and that schraeder valve is intact and tight, so you can get some better information out of it.

edit:
As far as oil, I'm guessing one of two things:
1. Oil that didn't get cleaned out ended up stuck in or at the bottom of the radiator. Shaking the radiator by cranking dislodged it.
Oil won't mix with water, and will be on /top/ of the water generally.
2. Sometime recently another oil-cooler O-ring failed and it's letting oil in. It might even be a 'partial' failure that is only happening when there's no back-pressure in the water jacket, which is why you didn't notice it before.

 

I guess then for now pulling the oil cooler and inspecting would be the way to go. New o-rings again.
I'll check the comp tester out and re do the tests.

 

Also Marcobb last time I ran the engine there was no coolant. It ran for 2 minutes tops so I don't think there would have been back pressure in the water jacket or would the GPs keep pressure in there???

 

No, that's the point. I'm saying that you *could* have an O-ring that didn't leak when it had 20 PSI of oil on one side and 10 PSI of water pushing back, but did leak with 20 PSI of oil on one side and nothing pushing back. That's just a theory, but either way it needs to be fixed.
GPs have nothing to do with anything oil or water related, so it's just a coincidence.

 

Understood. I did not think that the GPs have anything to do with that.
Is there anything else that fails that could allow that much oil into the cooling system so quickly? I can't have rotates the engine for more than 50 revolutions and I bet 2-3 quarts of oil came out of the lower radiator hose.
What is the direction of flow of the oil cooler? Front of truck to back or back to front.