Originally Posted by Bbasso
Try adding a very large transmission cooler not in front of the radiator. I did that on my 2003 and it reduced engine temperatures drastically.
By letting all the transmission heat dissipate in to the radiator it doesn't cool as much.
Where would you put the transmission cooler then? I added a large trans cooler to my 1998 E-350 V10 (I tow), and immediately noticed that not only does it keep the transmission nice and cool, but .... the engine cooling fan runs more often. I had actually never heard it before it it kind of scared me the first time - that sucker is loud! I wasn't sure if it was because the trans cooler is physically in front of the radiator (blocking flow), or because of heat coming from the trans cooler. OTOH, it was a bit of a feat just to fit it in at all, much less moving it around (it's right in front of the radiator, where the smaller, original one used to be).
I don't think my engine is running any hotter, but that's because the engine cooling fan comes on more often to bring it back down (seems to come on at around 200º to bring it back down to 197º or so).
The trans never ran really hot, but like to see it nice and cool when towing (i.e. under 170º). I have sometimes now wondered if I should go back to a slightly smaller trans cooler to keep the engine cooler (sans fan).