Truck overheating towing on long steep grades.

[mike-uswest]

The other day I came out of Death Valley to Beatty which is long and steep, but not that bad, but the transmission temp got up to 230 for most of the trip. I stopped part of the way up and let it cool before going on. This has happened a few time in the past, but I am looking to add a additional cooler if for nothing else make me more comfortable. The truck is a 2003 Dodge Cummins with less than 160,000 on it, and runs great. I would like to find an add on cooler that would not cost a mint and be an easy application to take care of this in the future. I have had it 15 years and other than this it has been a great truck. There doesn't seem to be a lot of room with coolers attached to the radiator now. Anyone have any suggestions? Thanks, Mike.

[Cummins12V98]

What speed and what gear were you in?

[Old-Biscuit]

Where you using 'tow/haul' mode?

Take it out of 'over-drive' so torque converter locks up...tranny temp will drop

[ScottG]

I take it you added the trans temp guage? Honestly, I don't think 230 is bad at all.
FWIW, your trans will drop out of OD if it gets to something like 265 degrees to protect itself.
But with that trailer, which is roughly a bit more than half your towing capacity, you should never have a problem with it overheating.

Another possibility is your clutch fan. If you have never replaced it, it's toast by now. You wont believe how differently a new one will act.
I strongly recommend using only the expensive OEM part.

[twodownzero]

I would clean the outside of your radiator and start there. It may be all you need.

[carringb]

That climb is probably the worst you can do. The speeds are low enough to don't get as much cooling as regular highway passes. Mine also hits 230F on that climb, but that's nothing to worry about for short durations.

What I did pull over for was my rear diff temp. I finally pulled over when the gauge maxed out. I good the diff once before, so I'm a little more careful now. But that's the only pull that gets that hot so soon.

[theoldwizard1]

230F is nothing for transmission fluid ! I worked design transmission over 30 years ago and even then we never got worried until the temp were above 275F ! Most fluid now a days is semi-synthetic or full synthetic so it is good for more than that.

[Cummins12V98]

Like mentioned I would make sure everything is nice and clean before doing anything else!!!

[Turtle_n_Peeps]

230F is not overheating the trans.

That said; Scott's ideas are good and it also would be nice to get a little more info on the ambient temp and RPM ect.

[RCMAN46]

To the OP.

What was your engine coolant temperature? Also what was the ambient temperature? What was your speed and engine RPM?

[ScottG]

After 15+ years, the radiator is probably not all that great anymore (I'm in the same boat). I would ensure it's performing at 100% before adding coolers - or, just replace it. With your current TT there's no way you should need more trans cooling. Then add a couple of bottles of "Water Wetter" and change the coolant.

I would also have the trans serviced and have the shop verify the torque converter is locking up. If it doesn't, it adds a ton of heat.

If you end up with another cooler, don't go cheap. You really get what you pay for with them and what ever you do, don't bypass the stock cooler.