Tru-Cool Max 40k Transmission Cooler

[Jlaughtr]

About a week ago I was towing a 16ft trailer with a 2-seater Polaris Rzr loaded on it. I was driving from NM to AZ and it was freaking hot. Around 105 degrees. As I was driving, I saw a cloud of white smoke shoot out behind my Tahoe. I pulled off at the next exit and looked underneath as best i could since the ground was 120+ degrees. I found a large amount of oil on the passenger side and it looks like it got on the exhaust and that's what burned it up. I checked the oil filer and it was good. I checked the oil level and it was good. I limped it the rest of the way and made it to a shop. The oil underneath had dried up, but they came to the conclusion that it was tranny fluid that shot out of the overflow port. When they check the tranny fluid the mechanic said it was damn near boiling because it was so hot. He recommended I get an larger external trans cooler.

I've searched around on the forums and haven't seen much about external trans coolers. Just wondering if anyone has installed or has any good info about them.

Thanks

 

[Jlaughtr]

This is the only thing I've found so far

 

[OR VietVet]

According to RA you have this cooler on your rig now if you have the heavy duty trans cooler RPO code KNP: https://www.rockauto.com/en/moreinfo.php?pk=3600450&cc=1434093&jsn=1516


If you don't then you likely have just the internal cooler in the radiator that is very small in comparison. If you have the cooler code KNP then check to make sure it is not clogged.

If I did not have that code and only had the radiator cooler, I would get the AC Delco one and plumb it all in with factory lines and mounting.


I do have the RPO code on mine and my cooler is right up front, just behind the grill. I also have code GT4 for the 3.73 gear and I bet that is why I have that cooler.

 

[Jlaughtr]

According to RA you have this cooler on your rig now if you have the heavy duty trans cooler RPO code KNP: https://www.rockauto.com/en/moreinfo.php?pk=3600450&cc=1434093&jsn=1516


If you don't then you likely have just the internal cooler in the radiator that is very small in comparison. If you have the cooler code KNP then check to make sure it is not clogged.

If I did not have that code and only had the radiator cooler, I would get the AC Delco one and plumb it all in with factory lines and mounting.


I do have the RPO code on mine and my cooler is right up front, just behind the grill. I also have code GT4 for the 3.73 gear and I bet that is why I have that cooler.

Yea I have the smaller external cooler. Since I live out here with such high temps, I am wanting to upgrade to a larger one so that it will cool better.

 

[08z71bgm]

This is the only thing I've found so far

This is cool. This would be the way to go for sure if you need a bigger cooler.

 

[Rocket Man]

The Tru-Cool 40k is the hands down go-to for our rigs. There’s plenty of write-ups on it in the forums and YouTube. It installs in the place of your tiny factory external cooler.

 

[08z71bgm]

The Tru-Cool 40k is the hands down go-to for our rigs. There’s plenty of write-ups on it in the forums and YouTube. It installs in the place of your tiny factory external cooler.

Wonder if this kit he spoke about works for the NNBS?

 

[Rocket Man]

Wonder if this kit he spoke about works for the NNBS?

Yes.

 

[OR VietVet]

It does look like the way to go. That new cooler cooler surface is 3 times bigger than the old one. The only thing I don't like is the compression fitting but if done right it should be good. That would be a constant source of inspection for me, especially during an oil change.

 

[Jlaughtr]

@08z71bgm

https://www.performancetrucks.net/f...kit-brackets-fittings-hardware-508374/page50/

This is the link to the forum where the guy makes the brackets for the Tru-Cool. I didn't read the whole thing but he does mention NNBS on there

 

[08z71bgm]

@08z71bgm

https://www.performancetrucks.net/f...kit-brackets-fittings-hardware-508374/page50/

This is the link to the forum where the guy makes the brackets for the Tru-Cool. I didn't read the whole thing but he does mention NNBS on there

Thanks. 75 bucks ain’t a bad deal at all for a factory mountable larger cooler.

 

[Rocket Man]

Thanks. 75 bucks ain’t a bad deal at all for a factory mountable larger cooler.

That’s for the brackets only. The cooler itself is about $175.

 

[Rocket Man]

It does look like the way to go. That new cooler cooler surface is 3 times bigger than the old one. The only thing I don't like is the compression fitting but if done right it should be good. That would be a constant source of inspection for me, especially during an oil change.

There’s a solution for that. You can change to braided stainless steel lines with -AN fittings either by making your own or you can buy a pre-made kit like this although to me this seller is making a fortune off these. I would buy the parts and make my own.

https://www.ebay.com/itm/283325432319

 

[08z71bgm]

That’s for the brackets only. The cooler itself is about $175.

I know it is. They are nice clean brackets and stuff and I don’t have to be bothered fabricating anything. Worth it to me. Time is money.

 

[08z71bgm]

There’s a solution for that. You can change to braided stainless steel lines with -AN fittings either by making your own or you can buy a pre-made kit like this although to me this seller is making a fortune off these. I would buy the parts and make my own.

https://www.ebay.com/itm/283325432319

I like this idea better than the compression fitting. I truly hate making these so if I need new lines I’ll prolly order these.

 

[Jlaughtr]

Thanks. 75 bucks ain’t a bad deal at all for a factory mountable larger cooler.

That’s only for the bracket system this guy came up with to mount the tru-cool 40.

 

[Jlaughtr]

Found this video explaining that this cooler should be mounted with fittings up. Start at about 27-28 sec

 

[OR VietVet]

Lots of explanation and thorough.

 

[08z71bgm]

Makes sense.

 

[gooffeyguy]

Uh, concerning what that guy in that video says about the mounting position.....

Cold fluid is thicker than warm fluid, thus why it will only run in the first few larger tubes when it's cold and you don't need all the cooling surface. As the fluid heats up, it thins and flows through the smaller tubes and utilizing more surface.

Kind of an internal thermostat for the cooler.

As for bleeding air, he said it's an open system with a vent and fill/dipstick tube, SO WHAT? It doesn't have to be a sealed system like the cooling system. The engine crankcase is an open system also. There's air in the oil passages, and on top of the heads under the valve cover and when the motor starts it has to push that air out so the oil can flow/drain...what a moron, lol