[444-4D]

If it were just mountain highways, I'd already have ordered the 6.0 cooler. Even pulling a steep pass, the engine is working so hard that the fan is running and the truck is making headway at least 30mph even if the fan isn't turning. But after just a couple miles of dead level, flat, bumpy dirt roads at 15 mph in near-freezing temps, my trans is breaking 200*. Understand that by "bumpy" i don't just mean "gravel road", i mean rocks and stuff. I'm keeping the speed low to avoid tossing everything in the truck and trailer, so it isn't moving forward fast enough to move much air thru the radiator and the fan clutch isn't locking so there's very little cooling going on.

What about a deeper pan? Does that do anything except look cool and snag on rocks (no lift kit on my truck)?

200° trans fluid is not an issue but to lower fluid temp, you need to replace your stock OTA cooler with a 6.0 OTA cooler. The OE cooling fan on your truck will move more air when unlocked than an electric fan will move.

If that doesn't solve your cooling issue, the next step is to replace your radiator with a later model radiator that has an OTW cooler in it. Then you run your fluid in a series thru the OTW and the OTA cooler.

A deeper pan will not be any help.

 

[444-4D]

200* was in cold temps; it'll go much higher in warm. Last week I forgot to watch my trans gauge on a road which started off fast-n-easy and then turned rough. When I finally remembered to glance at it, the temp had hit 280 (!!!!) and was on its way to the moon. Stopped immediately of course and idled but this tranny only has 25k on it and I want it to last, so don't need to repeat this mistake. Soon as I got back to town I put in Lubeguard and at my next break I'm going to flush the trans and add cooler & magnefine. I hope I didn't do too much damage. I also considered putting on an Insight monitor since I could set an alarm for trans temp...but I already have AutoEnginuity so I think it makes more sense to put the same money into a fix, rather than an expensive idiot light that mostly duplicates what I've already paid for in AE. Shoulda just got the Insight in the first place, I guess.

Thanks everybody for the feedback, especially the real-world results of using the 6.0 cooler at low speeds. That makes me feel much better about going that route, which is definitely my preference since it sounds like a straightforward and fair-priced mod. I am not in the mood for fussy, expensive mods right now : ) I will try to remember and update this thread afterwards.

When the radiator eventually needs replacing I'll definitely find one with OTW but I don't want to do that without trying the 6.0 cooler on its own, first. Especially since I just did a full coolant flush last month.

You should also check your cooler bypass valve to make sure it is working correctly.

 

[444-4D]

Nor to highjack but im interested in replacing my 6.4 F450 cooler w the TruCool 40k gvw model

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Why, is your fluid not getting warm enough?