Really confused here. Oil cooler and radiator questions.

Ok 2001 Chevy 3500 T Diesel Express box van.

So I started having what I thought were the common oil coolerlines leaking. Boughtsome nice lines from Leroy Diesel to replace them. Pop under the truck to verify that everything is gonna work and have the right parts before taking stuff apart. This is where things get weird. Ok. There’s the two ports coming out forwardof the oil filter. Trace those to the front where I expect to see my oil cooler. There’s no cooler but I can see where there was one previouslymounted. Notice that a section of rubber hose and hose clamps have been added to the hard lines and make a loop that is held up with a bungee. Follow the lines over and they go into the left side of the radiator (drivers side), one near the top just under the large radiator hose and one down at the bottom. Ok. This is where stumped. Does the factory oil cooler also have coolant lines that would have been connected to it as well as the oil lines and someone really screws up here and removed the oil cooler and just tied the four lines together and now there’s coolant and oil mixing

Most radiators have tranny oil lines that connect to the radiator like you stated.. It soumds like someone disconnected the motor oil cooler for some reason and didn't replace it and did a shade tree job..



You should check and see if the tranny fluid lines are looped, if so you should correct both with proper coolers...

Upon further research. It appears that someone installed a pre ‘94 radiator in it that has the built in oil cooler and transmission cooler. Oil cooler lines on the driver’s side and transmission cooler lines on the passenger side. I am drawing this conclusion because when I look up the 2001 radiator. It doesn’t have the oil cooler line ports on the driver’s side and the oil cooler is a separate unit. Ok. With that part figured out. How come when I took the oil line that runs from the block by the oil filter, loose at the radiator coolant is coming out, granted it’s dark like there is oil in it. Where are the two mixing? The truck runs like a top. Tons of power. No weird issues sounds or smells. The only reason I even dig into this was because the oil cooler lines started dripping in the driveway. Now I see there’s a bigger issue. My first thought would be head gaskets but would the truck be running soo well if I had a blown head gasket??

The cooler inside is just a coil of tubing, if it's cracked that is how it's mixing, you should see oil in the radiator cap area if it's mixing as well.. drain the motor oil and let it sit and settle or send in a sample for testing to be sure.. Either way this needs to be repaired..

Ok
Thanks for the info!

On to the repairs...

Ok
Got a chance to dig some more.
Pulled my oil cooler lines off. The upper one drained coolant out of it. The lower one oil. Pulled my upper radiator hose off and there is a ton of black oil sludge in there. Pulled overflow reservoir out. Same sludge in there. So here’s where I’m at. Did the internal oil cooler, built into this radiator, fail and then was circulating oil and coolant mixed. In which case. I’m thinking buy a new radiator without built in oil cooler and also buy a separate oil cooler. Try to flush my block. Install radiator and new cooler and call it good. Orrrrr. Is there an underlying motor issue that I should be investigating further first?

Have you drained the motor oil? If you have been running water oil mix for even a short time the bearings will be wiped out at the least.. it doesnt sound good so far..

Yup
There was coolant in there when I drained it.
So am I wasting my time/money flushing the coolant system and putting a new radiator and oil cooler on?

More than likely.

Worth noting.

There was no coolant in the oil when I initially drained it. I left the drain plug out and my pan under it.
Went up to the radiator and was attempting to disconnect the upper oil cooler line. When I started wiggling it. Coolant started running out of my oil pan out the drain hole. Stop wiggling it and it stopped. I may be being overly optimistic but my seductive reasoning is telling me that just inside the radiator at that line is broken and that when I wiggles it. Coolant was running down that line and into my oil pan.

Maybe just being hopeful but...

If you go for it, get some Simple Green and run in your cooling system. Used to see this done on big Cat motors when the would loose an oil to water cooler.