Replace Transmission Cooler with TruCool 40k

[Cory Dorning]

I have an 08 XL Denali with a stock cooler and am looking to replace it with a 40k but have a few questions...

- which 40k cooler do I need (thermal bypass or not)? I live in Northern Kentucky and tow a 7k lb travel trailer

- what other equipment/parts/tools would would I need to install this?

- considering doing it myself but depends on the difficulty. Any good videos of this out there? I searched but couldn’t find a Yukon specifically.

Thanks for any help you can provide.

 

[randeez]

https://www.performancetrucks.net/f...-fittings-hardware-508374/page29/#post5439440

Get that.

thermal bypass is up to you, i didnt install one but am also in south florida - i dont worry about it taking forever to get up to temp- it is also still going through the radiator cooler.
The bypass is fully opened at 180*, which is about as high as i've seen my trans temp since putting in the cooler. usually runs 135-140ish normal driving, if i drive spirited it'll start creeping up but i really have to beat on it for a while to see anything over 175*.
transmission does seem smoother when fluid is 120*+, so if you're seeing a lot of cold temps i would say throw in the bypass

 

[Cory Dorning]

My bigger concern is hotter temps. In upper 80* weather, I was hitting 200+ trans temp while towing. Trying to avoid that again.

Will likely go without the bypass and grab the kit you linked. Thanks!

Any install videos/guides out there?

 

[swathdiver]

I have an 08 XL Denali... and tow a 7k lb travel trailer

That's right up to the limits depending on how much the driver weighs and the how much weight the WDH can move off the tongue.

 

[Cory Dorning]

That's right up to the limits depending on how much the driver weighs and the how much weight the WDH can move off the tongue.

Yes.

 

[intheburbs]

Completely unnecessary, IMHO. Normal operating temperatures are 190-200°.

I've done this on multiple occasions, original transmission still shifts perfectly with 180k on it. 20k miles of heavy towing, including the Rockies and the Eisenhower Tunnel.

I f I were you, I'd be a lot more concerned about the rear axle than the transmission. Have you checked its temperature while towing? Have you checked your weights while towing? I'd be willing to bet it's either a) getting really hot, or b) overloaded, or both.

I'd upgrade the rear diff cover to one with cooling fins. I towed lots of heavy stuff with my half-ton Suburban, and it still has the original transmission at 250k miles, but it's on rear end number 4.

 

[Cory Dorning]

Completely unnecessary, IMHO. Normal operating temperatures are 190-200°.

I've done this on multiple occasions, original transmission still shifts perfectly with 180k on it. 20k miles of heavy towing, including the Rockies and the Eisenhower Tunnel.

I f I were you, I'd be a lot more concerned about the rear axle than the transmission. Have you checked its temperature while towing? Have you checked your weights while towing? I'd be willing to bet it's either a) getting really hot, or b) overloaded, or both.

I'd upgrade the rear diff cover to one with cooling fins. I towed lots of heavy stuff with my half-ton Suburban, and it still has the original transmission at 250k miles, but it's on rear end number 4.

Thanks for the input. I just replaced the rear shocks and suspension compressor. Had a full WDH alignment also.

Just curious but why do you suggest it's overloaded?

Just for comparisons sake, I took a 4 hour trip in 70* weather and the transmission never went past 185. Recently took a two hour trip in 89* weather and it hit 235*.

After some googling and browsing forums, just made me nervous I was running too hot.

 

[kbuskill]

It's never a bad idea, IMO, to upgrade the cooling capacity of ANY of the cooling systems in your vehicle since heat is ultimately what breaks down the fluids that are there to protect whatever system it is in.... especially the transmission.

 

[intheburbs]

It's never a bad idea, IMO, to upgrade the cooling capacity of ANY of the cooling systems in your vehicle since heat is ultimately what breaks down the fluids that are there to protect whatever system it is in.... especially the transmission.

Except, of course, if the "upgrade" prevents the system from getting to normal operating temperatures.

Thanks for the input. I just replaced the rear shocks and suspension compressor. Had a full WDH alignment also.

Just curious but why do you suggest it's overloaded?

Just for comparisons sake, I took a 4 hour trip in 70* weather and the transmission never went past 185. Recently took a two hour trip in 89* weather and it hit 235*.

After some googling and browsing forums, just made me nervous I was running too hot.

You have a 4200-lb rear axle weight rating, and a payload rating of 1500 lbs. A properly loaded/balanced trailer will have about 13% of its weight on the tongue. 13% of 7000 lbs is 910 lbs. Add the weight of your hitch, and that leaves you a little over 500 lbs for you, your passengers and all your gear. I hope you have small/skinny passengers.

Additionally, an SUV puts more if its curb weight on the rear axle, compared to a pickup. That's an additional handicap that limits how much you can carry/tow. So I ask again - have you weighed your rig to see where your numbers are? If not, I strongly suggest you do. 7,000 lbs is a lot of trailer for a half-ton SUV.

 

[kbuskill]

Except, of course, if the "upgrade" prevents the system from getting to normal operating temperatures.

This is very true... case in point, engine oil needs to get up to a certain temperature in order to burn off the condensation that occurs after cooling over night. This is one reason why allowing your engine to warm up to operating temperature is very important and why quick short trips are harder on an engine than long trips with continuous driving.

I live in Florida so not getting up to operating temperature is pretty much unheard of... lol

The transmission fluid still passes through the radiator before it goes through the external cooler which warms and helps regulate the fluids temperature and, if you do live in a cold climate, they have bypasses that are temperature activated, as I'm sure you know, which wouldn't allow the fluid to be cooled by the external cooler until up to operating temperature.