Radiator help! 1993 K2500 Suburban / oil cooler lines mismatch

[Doc Lolo]

Hi everyone,

I know this isn't primarily a mechanic-oriented forum, but I figured since so many of you have done mods on your trucks you might be able to help me. I'm really stuck.

I got a new radiator for my 1993 K2500 Suburban with the 7.4L 454 / towing package.

This is the radiator I ordered from 1A Auto Parts: Chevrolet GMC Radiator

Everything fits fine -- except for the oil cooler lines on the driver's side. They will not screw in and seem to be different threads from what is on the radiator.

Radiator: The internal diameter of the female fitting on the new radiator is 3/4".
Cooler Lines: The external diameter of the male fitting (O on the old cooler line is also 3/4".

So same (or very similar) diameter, but when I try to connect them they pop right out after half a turn -- they never engage. The threads seem to be different -- more coarse on the radiator and finer/more threads on the cooler line. I'm not 100% sure that's the problem, but it seems to be.

Any ideas what these threads are? JIC on the line? NPTF or something else on the radiator? Something else? And where to get an adapter to make this work?

Please help if you can, I don't know much about pipe threads and I'm stumped. 1A Auto hasn't responded to my emails. This was supposed to be a 2-hour job but now my truck's been out of commission for 3 days as I try to figure this out!

Thanks very much for your help.

.

 

[nitro_rat]

There's usually an adapter fitting in the new radiators. If it didn't come with any check your old radiator as see if there aren't any there. If you strike out there call who you bought it from and ask them for them. They should have been included. If all else fails a good local auto parts store or dealer should be able to help but you'll have to have a GOOD counterman to find them.