sansocal

Can a shop (or I) test the tranny cooler to make sure it flows enough?

Also how do I know if the tranny is overheating?

wjnfirearms

I'm not sure why you want to do this. Do you suspect the cooler is clogged? Anyway, if you disconnect it and run a fluid through one side and see the flow at the other, you pretty much could tell yourself. If you don't use tranny fluid to tell, make sure if is flushed out well before you hook it back up as not to contaminate the transmission.

If you look at the fluid currently contained in the tranny, and it is turning black, brown and/or smells burnt, you have been overheating it and it is heading down a bad road toward failure.

It's difficult to tell if the tranny is running hot just in of itself. They rarely overheat just under normal use, but if you are running the vehicle hard such as four wheeling or towing, it's a safe bet that you are running tranny temperatures up. Unfortunately, we often don't realize that we have been overheating them until we start smelling transmission fluid or they fail. Heat is the number one reason for automatic transmission failure. The temp will increase on a really hot day just during start and stop driving like being stuck in a traffic jam which is one of the reasons why I'm a big advocate of installing coolers even if you don't tow. Now, I realize that coolers don't work well with no direct air flow, but having them is much better than not. Properly positioning them during installation is critical also. I'm sure you could figure out how to install a temperature gauge or have one installed, which they are made aftermarket, if this is a major concern to you.

FYI, I have installed coolers on all of the XJs we have owned. We do occassionally tow a cargo trailer with the '97 (once towed my 24' travel trailer with it by necessity) and did with the previous '97. I sold the previous '97 with 210,000 miles, the current '97 has 248,000, and my '98 has 185,000 all on the original transmissions and no repairs to any of them. I firmly believe that the coolers play a big part in the longevity.

Trev1006

If you have reasonable suspicion to believe its clogged, replace it. Do you have an internal cooler in your radiator of an aftermarket one? Aftermarket ones are cheap, 40 or 50 bucks, better than a new tranny. I have trans temp gauges on both my jeeps. Wheelin an auto trans is HARD on it!