I'm getting oil in the coolant. Right now at the rate of 1/2 qt. per 100 miles. I replaced the heads because of this and now I'm wondering about the radiator oil cooler. This thing has really got me by the xxx. I used to think I was a fair shade tree mech. until now. Any thoughts or ideas? :confused: This is an 82 blazer 4x4 with the original 6.2 and 700r4

Welcome to the forum! :welcome:

The oil cooler is the logical thing to check. They have been known to leak on occasion. Before you purchase a radiator I would try bypassing the cooler and see if that fixes the problem... Don't run it hard without the cooler hooked up, though.

Hope this helps and welcome again! :)

It's messy but you can check the cooler by fabricating a fitting with a Schrader valve (tire fill fitting) to put air into the cooler. Remove the cooler lines, install the Schrader fitting in the top radiator cooler line fitting, plug the other bottom fitting, hook an air line to the Schrader fitting and slowly, with great care, pressurize the cooler while watching for bubbles in the radiator. If it leaks, bubbles will show. Make sure the radiator coolant level nearly full. According to an early GM bulletin, you can pressurize the cooler as high as 75# psi. If it is split, it shouldn't take that much pressure.

I use an adjustable regulator like the ones on the cylinder leakdown testers to add air gradually. I've found only two or three leaking coolers, over the years. Usually, if the cooler is leaking, oil will show up in the radiator as well. The oil pressure is greater than cooling system pressure, forcing the engine oil into the radiator. When the engine is shut off, the cooling system pressure is greater, causing coolant to flow into the cooler/lines/engine block.