I have a 2003 F150 Lariat. 47,000 miles. Transmission Fluid changed at 30,000.00. After I drive it for Approx an hour the OD light at the end of the automatic shift lever flashes. According to the code the transmission is overheating. The ford dealer says that the radiator and the transmission cooler has to be replaced because they are clogged and will not pass transmission fluid. The transmission is clear and passes fluid and the fluid is red, not at all burned. Seems weird that the radiators would clog when everything else is clear. To replace both radiators will be over 1,000.00 just in parts. The truck has never towed anything and has only lite duty. Anyone have a way to clear the radiators? Anyone else run into this problem with low mileage?

 

I would think that having the radiator flushed and filled would be an inexpensive thing, if you do it yourself. Don't know anything about the transmission cooler, but on a guess would think it might need to be replaced because it isn't functioning properly. I know I wouldn't trust the dealership without getting a second opinion from a different shop. Ford dealer, aw heck dealers in general, are notorious for misdiagnosis and over charging for parts. JMO

 

If it were me I would see if the rad cooler and external cooler are actually clogged. Unhook the lines to each and blow with your mouth. Once the fluid comes out it should be easy. If it isn't see it you can clear it with some compressed air.

The line comes out of the front of your trans and up to the top drivers side of the rad and out the bottom to the external cooler and back to the trans.