Oil in radiator 6.2 Diesel

A few weeks ago, I noticed my coolant temps go up a bit over normal. Nothing drastic, just a bit higher than it has been in years.
after about a week, I come outside one morning to find a large puddle
under the truck. Finally traced it to the radiator. Seems that something is leaking oil into my radiator water.
I ask folks, some say the heads ( truck still runs great ) my father says probably the oil cooler in the radiator leaking. No anti-freeze in my oil, but about a quart in the radiator.
I took the radiator off today and a new one is about 400 bucks.
but before I spend that much, I want to confirm with some others if this might be the issue>?
makes sense to me, as the oil pressure is 30 to 60 pounds, and the radiator cap is 15 psi.
the oil was leaking from the radiator overflow bucket and when it filled up, it ran over on the ground.
when I took the radiator cap off, about a quart came out. Since the oil is lighter than water, the bottom half of the radiator had antifreeze.
So somebody tell me I am on the right track, as i DO NOT want to take the heads off in an exploratory move...
replacing the radiator is fine with me.
SECOND question. I am looking at an aftermarket oil cooler, and eliminating the oil cooler in the radiator altogether. anybody have one of those?
oil cooler is 225, new radiator 400. I could plug the oil cooler lines and use the same radiator if this is the case.
mel
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Greetings,
First you have some missing information. Need to know if your engine oil level is lower on the dipstick. If not, then check the fluid level in your transmission and see if that's the source because unless you have a set-up I am unfamiliar with, the "oil cooler in your radiator" is actually the transmission fluid cooler. The actual engine oil cooler is a smaller seperate radiator that sits either in front of or below your normal radiator but had no direct connection or shared pieces parts with your radiator. It is not uncommon for vehicles with radiator issues to have the tranny fluid leak into the engine coolant from a bad radiator, which cools both fluids separately inside one unit.
Second, if you believe you have problems with the heads don't pull them just for an inspection. Do a cylinder pressure test first to see if you are holding pressure which can point to a bad head gasket a lot easier than pulling the heads.
You should also do a pressure test on the coolant system as well, which might tell you if the intake manifold gasket is leaking - although this would typically put coolant into your engine oil and not engine oil into your radiator.
Good luck - Jonathan

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Jonathan wrote:

GM uses an oil cooler mounted inside the radiator on many vehicles. They have a trans cooler on one side and the oil cooler on the other. Been in use since at least 1990.

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Greetings,
You are most likely correct but I've not seen this set-up on any of my GM trucks. In my last two diesels (a 6.5 and my current Duramax) the oil cooler was a completely seperate unit and only the tranny cooler was incorporated into the radiator. While I've tinkered with the older 6.2 diesels I've never owned one like the OP and the only way to be absolutely sure would be to look at his truck.
Cheers - Jonathan

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OK number one... no automatic transmission, and the only cooler lines are the oil cooler lines from the motor.
Number two, yes the motor was a bout a quart low when I saw the puddle under the truck. No antifreeze in the oil.
I could do a compression test on the motor, but I don't think it's the heads. Motor starts and runs good, plus on diesels, it would run bad and I would be seeing weird smoke and blow by.
I'm gonna go ahead and pressure test the oil cooler section and see if that leaks air.
Should be able to do that with an air compressor, as it the oil pressure on this truck is 60 psi when it starts.
Radiator is out of the truck now. WHEW... and WHAT a MESS. took three bags of kitty litter to soak it all up.
mel
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