Leaking coolant and oil in coolant - Diesel Forum

cutsman · 11-04-2009, 01:58 AM

Hello,

I have a 1989 F-350 7.3 IDI. About 180,000 miles. I have owned it for about 6 months. Runs well and seems to have been taken care of, though I don't know its entire history.

It has just recently started spitting coolant out when the engine is first started. The leak appears to slow down and maybe stop as the engine warms. I looked at the coolant and there appears to be some oil in it as well. It has turned from a bright green to a brownish color and there is some oil on the radiator cap.

I drained some oil from the pan and it does not appear to have coolant in it, so my thought, or maybe just my hope, is that it isn't the head gasket.

Also, when the engine is started, there is an intermittent and barely audible "sucking" sound, like a vacume or pressure leak. It's not loud and generally goes away after the engine warms up. I noticed the sound a few days before I noticed the leak. This may or may not be related I suppose.

The leaking coolant is coming from the front of the engine/engine compartent, appears to be toward the driver side, though it is difficult to tell. It comes out in a steady drip when first started and then slows after warm up (5-10 min).

Oil pressure has dropped to the lower side on the gauge, but is still in the normal range, not sure of the exact psi though. Engine runs fine -- no overheating and no starting or running issues.

Any ideas? Could this be a failing oil cooler or even just failed oil cooler gaskets?

Thank you.

cdnsarguy · 11-04-2009, 07:29 AM

Your symptoms are that of OIL COOLER oring failure.... visit my photo link for info on the cooler, also there are many post re personal fixes and stories in the archives here.

Kevin 007 · 11-04-2009, 12:34 PM

I second that! he's got great photos of the cooler...take a look.
Mine is leaking ever so slightly too, gonna be my next project haha...always something.

cutsman · 11-05-2009, 04:47 PM

So I got up underneath the engine and inspected the oil cooler. The cooler element appears to be in good condition, very little rust or corrosion, same for the headers. The header gaskets appear to have been seeping oil for some time, not a gigantic concern, but if I'm taking the time to pull the cooler I'll go ahead and replace those. Coming from the front header with the engine running is a light spray or mist of coolant, so my plan as of right now is to replace the o rings and gaskets and try to save the cooler. Not looking forward to having to pull the cooler off though, haha, looks like a pain.

Thanks much for your help guys.

87CrewDually · 11-05-2009, 10:41 PM

To remove the cooler you'll need to unbolt the 2 bolts for the motor mount and jack the motor up so it tilts toward the passenger side. This will give you room to slide out the cooler from the bottom towards the rear of the truck. You may be able to access the cooler bolts through the wheel well easier than from the underneath.

To reassemble the cooler with new o-rings it's easiest to press the housings back on. Make sure you use petroleum jelly on the rings to aid in the assembly.

lexxxel · 11-05-2009, 11:30 PM

I had my oil cooler rebuilt this summer. (rebuilt, really just cleaned and new orings).
I always had a little oil leaking... but it started dropping like crazy and was coming from the oil cooler. Luckily there was no oil/coolant mixing

You should have seen the sludge that came out of the cooler. It was soaked overnight to get the crap loose.

The guy who brought my truck from out west had a coolant leak on the drive (3000 miles), and must have put rad stop leak in it at some point. That **** is awful and goes places you don't want it. NEVER use that stuff unless you want problems later on

I've now replaced the rad, heater core, all hoses, rebuilt the cooler, and I think all the sludge is gone.