Auxiliary Transmission Cooler?

thearizonacowboy · June 26, 2018

I'm looking to see who has installed an auxiliary transmission cooler on their truck. I have a 2018 5.3L 1500 and will be doing this within a couple weeks. Just looking to get ideas first!

No, I am not open to a new thermostat and yes I need the auxiliary trans cooler.

Thanks!

txab · June 26, 2018

If you don't override the built-in thermostat you may not accomplish as much as you'd like. You'll still be able to shed more heat with more cooling surface area, but you'll be held to the 190 or so temp. Many models to choose from, always go with a stacked plate/fin unit. Stay away from tube and fin.

thearizonacowboy · June 26, 2018

7 minutes ago, txab said:

If you don't override the built-in thermostat you may not accomplish as much as you'd like. You'll still be able to shed more heat with more cooling surface area, but you'll be held to the 190 or so temp. Many models to choose from, always go with a stacked plate/fin unit. Stay away from tube and fin.

I'm completely fine with 230 and below. It's the 240-250 that I don't want haha.

I have a Derale fan unit I could install but I'd rather not go that route if it's not needed. I've been looking at the Tru-Cool 4k unit and that seems like more of a plug and play application. I've heard a lot of Chevy guys use them on the older trucks and have had great luck

Jon A · June 26, 2018

Under what conditions are you getting such temps (high speed, low speed, towing, offroad, etc)? Have you tried reprogramming the fans at all?

Do you mean the Tru-Cool 40K GVW MAX cooler? If so, that's a really good cooler and would offer a ton more cooling capacity. Of course, if the radiator fans are barely moving and your grill shutters are closed when you're having the issues, it may not solve the problem.

Personally, if I had determined more cooling was needed (not an airflow problem) I'd be inclined to go with one of their smaller Max coolers (mini or medium) and use that in conjunction with the stock cooler. This would lessen the impact the cooler has on engine cooling and A/C performance. The stock cooler is pretty big and a good design, it would be a waste not to use it.

While it's true, in theory, the thermostat shouldn't be a factor at those temps, in my opinion the stock design leaves much to be desired. We've had at least one guy here who had a faulty one and it was causing all the problems by itself so that's another possible issue you'd want to be aware of.

thearizonacowboy · June 26, 2018

42 minutes ago, Jon A said:

Under what conditions are you getting such temps (high speed, low speed, towing, offroad, etc)? Have you tried reprogramming the fans at all?

Do you mean the Tru-Cool 40K GVW MAX cooler? If so, that's a really good cooler and would offer a ton more cooling capacity. Of course, if the radiator fans are barely moving and your grill shutters are closed when you're having the issues, it may not solve the problem.

Personally, if I had determined more cooling was needed (not an airflow problem) I'd be inclined to go with one of their smaller Max coolers (mini or medium) and use that in conjunction with the stock cooler. This would lessen the impact the cooler has on engine cooling and A/C performance. The stock cooler is pretty big and a good design, it would be a waste not to use it.

While it's true, in theory, the thermostat shouldn't be a factor at those temps, in my opinion the stock design leaves much to be desired. We've had at least one guy here who had a faulty one and it was causing all the problems by itself so that's another possible issue you'd want to be aware of.

Offroading in 100+ temps at low to highe speeds at an incline. Pretty bad combination haha. As soon as the incline drops off and the speeds pick up, the temps drop considerably... Maybe I do need more airflow.

I have this smaller Derale cooler and it's starting to sound like a good solution. I can do just about anything suspension and body wise on a truck but I've never tried wiring and plumbing a transmission cooler so I'm a little intimidated. Wouldn't know where to begin with fittings, lines, etc.

Thanks for your help so far!

Jon A · June 30, 2018

Those conditions can be challenging. Especially on slower hill climbs, you'll have lots of converter slip creating a lot of heat, but little airflow to make the coolers work. I haven't followed the 2018's too closely, are they able to be programmed yet and would you be open to it if they are?

That's the most elegant solution--the radiator fans on these trucks are large and powerful, but with the stock programming they'll only be spinning at around 20%-30% power under these conditions. Cranking those on more aggressively with a tune would likely solve your problems completely without turning a wrench.

Also, under those conditions, the in-tank cooler in your radiator is actually acting as a heater (or highly ineffective cooler) the vast majority of the time. You can drop your coolant temps 30-40 degrees with a new thermostat (much cheaper and easier to install than a trans thermostat) which will make the cooler in the radiator tank actually help cool your trans fluid quite a bit. Of course that requires the fans be turned on via programming to be effective at low speeds as well.

If tuning isn't an option, you may need to add something like the Derale above. It would be a hassle and have downsides, but it is doable. It looks like the one you have pictured above is a tube&fin, personally if going to the hassle of installing it I think I'd spring for one of their plate&fin models as they're much more effective. Also you'll want to verify the fan is designed to be usable as a pusher fan (reversible) , not a puller only (if designed to be a puller only, it will be highly ineffective when wired as a pusher).

Another option would be to add a couple pusher fans in front of the radiator to make the stock coolers more effective as mentioned above but without having to program your stock fans. They wouldn't be as powerful, but they might get the job done and you'd avoid plumbing trans lines, just wiring up to power and a switch.

Beyond that stuff, obviously gears will help, reducing converter slip, as well as using low range even when it's "not needed" for lower speed stuff.

XSKIER · June 30, 2018

I put the derale plate style cooler with 180° switched fan after the internal radiator cooler on my truck. It is an 07 AVY with a 540 hp LS3, 3800 stall, 4L70E. I can keep the bitch floored in 90° weather without raising the trans temp on the DIC over 200°. I also have a stock '17 6.0 2500HD, that struggles to make 120° on the DIC. You might consider just buying the HD transmission cooler and sticking it in your LD.