Radiator questions...

[SteveRosenow]

PTFE tape will not hurt anything if you use them on the threads. Also, I am guessing you checked that the O-rings were in place prior to installing/connecting?

Yes, there were O-rings on the new radiator. In fact they were really well seated into the new fittings, which themselves had a healthy amount of thread sealant applied onto them from the factory.

Even with the new O-rings and following every instruction/piece of advice in this thread, I still ended up with a bad leak. In fact, I lost an estimated half quart to almost a quart of ATF in the runup/warmup test and my engine bay was literally dripping with ATF.

 

[crunchie_frog]

I am guessing it is leaking at the connection at the flared fittings and not at the connection at the radiator housing. If it is the flared fittings, take them apart, check to be sure they were not cross threaded, try PTFE tape, then retighten, being sure you have a wrench on the nut connected to the housing as well while you are tightening the flared fitting. I am guessing you have a flare nut wrench, really the best tool to tighten this fitting up.

 

[SWIGIN]

It's not tight enough or the flare is damaged if it's leaking.