Hello I was on highway while hauling my trailer (3500 pounds) and my transmission over heated (red light on the board) but the motor seemed to be ok ( temperature right in the middle as usual...)

I stopped and notice that only the main fan was running. Is the small fan/cooler set on the right side of the truck , I assume that this is the transmission oil cooler. This fan was not running... did it ever run ??? I never had any problem reg transmission temp before but it is the first time I do a long run (500 km) with my new trailer.

So few questions :
1 : is the small fan the cooling fan for the transmission oil?
2: I did not find any fuse for that fan, is it fused separately or with something else (and what else?)

Any other comments/suggestion would be appreciated...

Philippe
2001 rodeo
4wd V6

The small fan is over the AC cooler thing. There is no external tranny cooler (but it has the normal cooler which is built into the side of the radiator).


What is the fluid change history on your tranny?

If you tow regularly I would recommend you have installed an aftermarket tranny cooler.

I changed it the last time at 60k miles and I'm at around 90k miles (note that before this summer, I was not traveling with this trailer (I had a small 2000 lbs popo trailer tent) I intend to change it pretty soon (on my next oil change, in few days...) A buddy at work also told me to switch in 3rd if I see that I seem to be between two speeds (around 60 mph with such load...) The tranny did not seem to heat up when I was in hills (I had aroud 200 miles in very ruff conditions but it was fine....)

You're gonna want to ALWAYS manually downshift this tranny if you're hauling a load over 2,000 lbs; especially in the hills (any kind of hill really) the *engine* was designed for this kind of load, the *tranny* is not.

The GM 4L30-E tranny's in these trucks are underbuilt for what the engine can do; it is best to baby this tranny if you will, rather then leave it in overdrive (hunting between 3-4th gears).

My 97 regularly towed a 4,000lb trailer for a great portion of it's life, I have just in the last year retired it from towing anything over 1,000# primarily because I now have a bigger truck, and I've had good luck with my original transmission in this rodeo, and at nearly 175k miles, I don't want to push it.

However, I am NOT saying this truck can't do it, just make sure the minute that trailer leaves your yard, that tranny's in 3rd - always! Only exception to this is complete flat-land driving, where 65mph comes easy, but I do NOT recommend going faster the 55-60mph with this kind of load.

The truck can *pull* it, but if you were caught in a cross-wind, and or had to stop immediately - forget it! Won't happen.

I highly recommend doing several drain/refills on that transmission over the next 1k miles to get all of the burnt fluid out - it will not last long with burnt fluid staying in it, so do as LITTLE as driving as possible until at least 50% of the fluid is swapped.

You can replace up to 3.5 qts in one drain/refill procedure; I recommend doing at least 3 times in less than 2k miles. And do not tow that trailer again until new fluid is put in, or you risk loosing it.

FWIW - I myself have never installed an aftermarket transmission cooler, but I do perform partial ATF fluid changes every 15k miles, and, with living in the Rocky mountain region, the truck stays in 3rd whenever a trailer's hooked to it.

Also, try not to gun that truck up a hill with a load, sit back a bit, and allow it to climb at a moderate pace - basically, expect the drive to take longer then you would otherwise expect without a trailer or a smaller trailer.

I for one, can make it to Vegas, NV climbing over I-70 with a loaded Rodeo in say 8-10hrs, stopping only for quick food and bathroom; traveling that same highway with the heavy trailer, it can take 13-15hrs depending.