goclmbmnt

I have a stock 2010 Suburban and tow a boat a couple of times a year up and over one of the gnarliest passes, the Colorado I-70 corridor, Vail Pass & Eisenhauer Tunnel. Boat weighs about 5,500-6,000 typically loaded and my kids are all lightweights right now. My suburban does a decent job pulling the boat to other lakes, when the terrrain is more flat, but once we start on our annual lake trip over those passes, my blood pressure starts to skyrocket, even before the tranny temps start climbing. My biggest challeneg is the tranny temp slowly climbs when I hit those steep grades. My speed obviously slows so as there is less air moving past the cooler, the temp starts climbing. Not to mention less air density at 10,600 ft! So I'm thinking if I can keep air flow past the cooler, that might help?

It has the standard tow package with a tranny cooler factory installed. I've talked with my local mechanic about options/upgrades to help keep the tranny fluid cooler and he suggested adding an auxiliary cooler, additional electric fans, or a mechanical fan. Obviously each has its own pros and cons... but any advice on which would be the best solution to help cool that transmission fluid?

I poked around and didn't find a similar question... Thanks in advance for your thoughts and suggestions!

intheburbs

Dex6 can handle very high temperatures. The "trans hot, idle engine" warning only comes on at 265°. For only a few times a year, I wouldn't worry about it.

This is what I did last year in my Suburban on the climb towards the Eisenhower tunnel...rig was 16,000 lbs.

goclmbmnt

Thanks Intheburbs. At 16,000 lbs, is your truck a 2500?

I'm aware that the fluid can handle the higher temps, but it's still nerve racking to watch the engine and tranny temps climb steadily. I'm planning on keeping this truck for a while and making that annual trip, among others, and am hoping to find something to improve the cooling.

02Sub

On a previous Suburban I installed a Derale plate-type cooler. The plate types are more efficient (and expensive) than the regular tube-and-fin type. Since you will be travelling slowly uphill, air flow is an issue as you stated. If you are going through the trouble to install an additional cooler, I would get a fan-cooled plate type cooler like this one:

Fluid Cooler

Some of the coolers have a thermostatic bypass to avoid overcooling the fluid in cold weather.

Steve

goclmbmnt

Thanks Steve! I agree, if I go through the trouble of an additional cooler, i want the best, most efficient one out there. I'll check that out.

intheburbs

Yes, it's a 2500. It has 185k on it, still everything is original and runs perfectly. This truck has had a hard life, with over 20,000 miles of heavy towing, and my overall driving style.

A friend of mine works for GM as a transmission validation engineer. He works at the Milford proving grounds, and basically gets paid to beat the snot out of vehicles. When he was hired at GM, his first validation project was the 6L80/90. I was also concerned about the higher temps I was seeing, and he assured me they did much worse during validation, and no additional cooling was necessary. That was five years ago. He seems to have been correct, at least with my data point of one.