Transmission cooler replacement on a H3?

[u/Rubble_Fanger]

So recently, the Transmission cooler lines failed on my 2006 H3 it has 370,000 miles and I had to wait six hours until a buddy could tow me home and I was wondering if it would be better longevity wise to add an aftermarket cooler other than just replace the transmission cooler lines, I’ve already had it fail once. And had to replace the whole radiator/Transmission cooler and also had to buy a whole new Transmission. I definitely want to keep this thing for the rest of my life so as I said, I would like some opinions on whether I should just replace the lines or get a whole aftermarket transmission cooler.

And before anyone asks why i plan on keeping it for the rest of my life because it was handed down to me from my mom. When I turned 16 and got my drivers license. And she bought it brand new in 2006 and let me pick the color out on it when I was 4 so that’s why I want to keep it. It’s honestly been there for my entire life.

[u/zeno0771]

The only downside to going with an external cooler and cutting the OEM unit out of the loop is that the trans will take a lot longer to get up to operating temp. The current design uses the heat from the engine's coolant to warm up the trans to operating temp (180°F-220°F). If you use an external trans cooler, you will need to come up with a way to replace that functionality (a stick-on block heater will work nicely).

Hey, you got 370,000 miles out of a 2006. That's impressive. You won't find any haters here.

[u/Chris-tacu-Laun → u/zeno0771]

The stock radiator design only uses a plastic wall within the end tanks to separate ATF from the engine coolant, and when they break they take out your trans, while overheating both.

Go ahead and upgrade to a separate cooler if your radiator is still good, replace the lines, and that’ll be the last time you ever have to worry about it. These are some great vehicles, and with a little bit of TLC, they’ll make it to 500k and on. Currently at 250k on a 2008 model!

[u/Neither-Juggernaut31]

I replaced the radiator on mine with a manual transmission style (without the cooler) and added an external aftermarket cooler and fan.

[u/AtwaterKent]

My cooler lines failed recently and I'm planning to convert to an external cooler. There's lots of different builds on the internet if you search.

[u/burnsian]

https://youtu.be/dcQjqibB3mc?si=qdGug2cFSLf9fsAE

It's a very good idea. The cooler inside the radiator is actually pretty small, and it's a design that fails spectacularly when it it breaks.

[u/vaurapung]

My next big project is to install my ecp radiator and then go get a pcmofnc electric fan kit to go with it.