One of the trans cooler fittings on my radiator is leaking. So i figured it would be a good time to add the trans cooler that I bought last year and never installed. The question is, which line should I hook it up to? The upper or the lower? I would like it to go to the factory cooler, then to the after maket and back to the transmission. Or is there another way I should hook it up?

 

I dont know which line in this instance. I do know that a trans can be operated under temp during warm up. When I put one on my Gen1 I put it in the trams to radiator line so the temp would be more consistent.

 

If I remember correctly (??) the trans fluid flows from top to bottom; so from trans into the top of the radiator, return to trans at bottom radiator connection.

I installed the cooler on my '02 at the top radiator connection; hottest trans fluid going into cooler and then back into radiator to be warmed by coolant temp and then back to trans.

Just did this earlier this summer so unknown as to any effect this winter will have on trans operation.

 

Yes i recently put in a secondary tranny cooler. You will disconnect the top line. run from radiator to secondary cooler then back to the tranny. I found out the hard way of doing this and had tranny fluid everywhere. It was pretty easy though. Also make sure to use thread tape and tighten everything. I had a small leak but it sealed right up when used the thread tape.

 

Also i have a 2000 Blazer with the 4.3L in it. Just to clarify it runs from tranny to bottom of radiator, top of radiator returns to tranny.