Trans Fluid Leak
 

After replacing my radiator with an aluminum radiator on my 85 4+3, I have been chasing my tail trying to stop a leak at the compression fittings on the radiator that acts as the transmission cooler. My question is, can I use plumbers tape to try and seal the threads or is the heat too much for the tape?

Yes you can use teflon tape.

Whose radiator is it? I have had this situation before. They mfg'er tapped the pipe threaded holes too deep. (I believe the company was simply buying bungs made by someone else). Foreign made fittings were cut to the minimum size and wouldn't seal, US made, barely. I had to take the barbed pipe fittings and turn them back on a lathe to get them to seat deeper and seal, which is not so easy to do with a fitting on a tube.

You might have to use the thicker tape (pink/yellow) to get it too seal. If that doesn't do it, you might need to discuss a return.

It is a Champion Radiator from JEGS. I will try the teflon tape, and hope it works! Thanks for the info!

OP - I believe it's important to use what the radiator is fabricated for - you mention 'compression fittings' and I'd think that most fabrications would like to see 'inverted flare' to the cooler. Maybe you need to better explain just how you have the plumbing done, whose radiator you have etc. Is your leak at the cooler where the tubing is attached directly to the cooler or are you using 'compression fittings' in an attempt to splice newer to old. Compression fittings often don't work well when used to 'old/original' tubing with deteriorated external finish.

**** I'd expect likely 5/16-inverted flare on most fabrications - Champion mentions 1/2 - 20 and that I believe would be appropriate for 5/16 Inverted Flare.

Sorry I know next to nothing about fittings and plumbing. It is the original fitting from the 85, going into the new radiator.

The original fittings on the lines are likely 5/16 INV FLR and if you inserted them into a 1/2-20 straight thread bung it would never seal. I edited my earlier post and it appears it didn't stick. 1/2 - 20 mentioned by Champion if it were just a bung with no seat for inverted could be your issue.

Call Champion or Jegs and get the specifications of the trans cooler line connections. Are they intentioned for INV FLR or do you need an adapter to mate them to OE fittings/lines.

***** There should be several users that have used the same Champion as you did. I'd think someone with 'hands on' experience will likely stop by.