tranny heating

[coopers dad]

I run an 04 duramax 3/4t and always tow a featherlite trailer (4000lbs) and 2 horses (1200lb ea). Last week was 100 degrees and we were late between rodeos, all we could get was 70mph before the tranny started heating. Meanwhile buddy roasts by with a 04 gm dually towing a massive 4 horse unit with living quarters (double our weight), What was his secret?, and what should I do to prevent the heating?

[DmaxMaverick]

Welcome aboard!

How hot is hot? And, are you using the T/H mode? If the tranny temp gets quickly into the red, you have a problem, but we need more info. Towing in non-T/H mode will cause higher tranny temps. However, at 70 MPH, it shouldn't make that much of a difference.

[Gapper_ca]

i had my tranny temps rise last weekend when i was going home from a trip to the lake. temps where 30 + C into a very strong head wind. Pulling the TT and Boat at 60. tranny would get up to 210 to 220 . i was running in OD some of the time. would lock out OD for the hills and such. temp would drop back donw to 200 or so then climb slowly. Engine temp would go from 195 to 220... Fan seems to keep it in check most of the time. A few times i turned AC off. Temp would drop right down quickly. I think some of my problem is teh bug screen that i have., one of those stainless steel inserts. i am going to remove it and place a screen inside of the grill so that i can remove the insert when towing so that i will have max airflow for cooling but still have bug screen. need the insert in when driving the grid roads to stop the rocks from going thru rad.

[Mark Rinker]

I would expect to see temps around 200-210 based on you description. Was it higher than that?

If so, check to see how your cooler stack is looking, it might be full of bugs, weed seed, etc.

We have cleaned all truck's A/C condensers, radiators, intercooler and transmission cooler stacks this summer, lots of bugs plugging them.

The Kodiak A/C system went overpressure while idling with air on in the driveway on a hot day, venting all the freon from the rear of the compressor. I experienced this firsthand and it was VERY disturbing until root caused was discovered!!! Cleaned, evacuated/recharged and all back to normal. Water temps are running cooler as well.

[killerbee]

I run an 04 duramax 3/4t and always tow a featherlite trailer (4000lbs) and 2 horses (1200lb ea). Last week was 100 degrees and we were late between rodeos, all we could get was 70mph before the tranny started heating. Meanwhile buddy roasts by with a 04 gm dually towing a massive 4 horse unit with living quarters (double our weight), What was his secret?, and what should I do to prevent the heating?


Did you both have LLY's? His 04 might have been an LB7?

The LLY has an inherrent induction hardware flaw that makes it very hot under high loads. The superheated CAC passes this heat on to the radiator, where your tranny temp is mainly regulated.