Is there a trick to getting the tranny cooler lines to not leak? I have just put a new engine in my 1997 GMC Jimmy and the tranny cooler lines seem to be leaking at the radiator fitting. This is a new radiator with new quick connectors. The lines seem to push into the connector alright, but are leaking. Should I try to use the old connectors from the old radiator? Or is there a simple way to make these quick connection joints leak free?

 

The first 'trick' is to make sure that there is no tension on the lines. They have to almost want to go into the radiator fitting on their own. Any side-ways or up/down pressure in the quick connect (especially aftermarket quick connects) can cause leaks.

And second, make sure that the e-clips are not bent out of shape. When placed on a flat table, they should lay perfectly flat. Any bow up/down in them will not allow the pipe to fully seat into the quick connector.

 

Just a follow up for everyone. I have been able to fix the leaking tranny cooler lines. I tried swartllk's recommendation of making sure there wasn't tension on the line, but I had no luck using the connectors that were sent with my new radiator. I switched back to the old connectors that were on my old radiator and they sealed up. I don't know if the lines and connectors were matched to each other or not. All I know is that they are not leaking now.