Transmission Cooler question


I have a '98 Pontiac Sunfire 2.2 with a 3 speed automatic. It’s developed a transmission fluid leak where a metal line connects to the radiator. I attempted to replace the line, but the bolt was corroded and I felt it was going to damage the radiator if I forced it. So temporarily I made a patch with some rubber hose and some hose clamps. That patch has run it’s course. The car is worth very little, so I’d rather not put much into it (i.e., new Radiator) if I don’t have to.

So my question is… How bad is it if I just clamp off that coolant line? I don’t drive the car under harsh circumstances. Generally just a 14 mile commute, flat terrain, 66-70mph tops. I’m only looking to get another 3-6 months out of the car… and don’t want it gushing tranny fluid on my driveway.


That connection at the radiator is for the transmission cooler. If you just plug this line the transmission will overheat and fail. Have you looked into an aftermarket tranny cooler and just by-pass the tranny cooler in the radiator altogether?



No coolant to keep the tranny cool and it’ll burn out quickly. 60-70mph tops.!? You’ll need that speed to coast to your nearest scrapyard for a used tranny.

Heat is the trannys worst enemy.


To clamp off the lines is death to the transmission. The next worst option is to loop the lines together with a single piece of fuel-injection rated or transmission cooler hose. This will let the fluid circulate, as required, but not cool. The cheapest long-term fix is an auxillary transmission cooler mounted in front of the radiator. This will allow for better cooling, and is used to cool transmissions that see more work that normal, like towing or sustained high-speed running. Here’s a kit from JC Whitney that you can add for $52.00.