Nissan Repair: radiator and transmission, nissan frontier, pep boys

Question
2001 nissan frontier, 170k, auto trans. At 90k miles my trans went bad , no warnings, no slipping, etc., while driving. It suddenly started grinding and not shifting and would not go into reverse.Had trans repairs done at a local trans shop and the mechanics told me that the radiator cooler(internally) had clogged, stopping the flow of trans fluid. I have always had a trans service(fluid change and filter and gasket) done every 30k miles. My question is, is this common? Should I just put a new raditor in now? Could the radiator be tested for this? Thanks for your time. Bill

Answer
Bill,

I would recommend replacement of the radiator with a heavy duty unit.  Also, install an aftermarket cooler like a Hayden 404.  Pep Boys is a good source for one of these and they can be obtained for about $50 bucks.  Well worth the investment to keep the transmission fluid cool.  The factory unit, in the radiator, is just not up to the challenge of cooling your fluid.  I install the Hayden 404 in all of my vehicles.  Cheap insurance...  You did nothing wrong since they only make the transmission to last 100K miles.  So, look at it like you got an extra 70K miles for free...  I know it sucks.  But, it did last much longer than most.  You could have the fluid changed at a shop that uses a pressure system.  This is where they tie into the transmission line, at the radiator, and purge the system of old fluid using a pump and that should clean out the cooler.  But, if the fluid is not running too hot, as with the additional cooler, the fluid should never get hot enough to coke up the cooler in the radiator.