Trans cooler o-ring replacement

[BaconBandage]

Hey everyone- long time no post. Just did the set of lower trans cooler lines on my '05 4.3, and have a leak. It's coming from the fitting at the radiator end- is it possible to replace just the o-ring? Anyone know the diameter that I would need? Really don't want to deal with pulling the fitting and having coolant go everywhere. No idea if the radiator is stock, but it has the fittings with the big flange on it, no separate quick connect fitting to easily replace Thanks!

 

[Mektek]

Yes, the o ring can be replaced. I don't remember the exact size but it was a standard one in my kit. It's easiest to match the correct size if you unscrew the fitting and work on it on a table.

 

[BaconBandage]

Well that could have gone better... ended up getting the dorman fitting (#800-619) locally, plucking the o-ring out of it, and attempting to stuff it in the fitting already on the radiator. Just could not get it to seal- it was leaking at the same rate as the rotted line I replaced. Putting the original o-ring back in changed nothing. So I said 🤬 it, backed the fitting out of the radiator, and to my surprise no coolant came out! Got another new fitting, installed, and after a bit of tweaking to make the pipe happy no more leaks! Measured the dorman o-ring from the first fitting, it's just a hair under 3/8 ID (probably because of the mold line), and has a .07 cross section (so a bit bigger than 1/16"). So if anyone else is reading this, try slowly backing out the fitting (19MM socket/wrench), and if no coolant comes out, just replace the whole thing.