transmission cooling auxiliary or stand alone

[PT Sportwagon]

I am wondering if it would better adding an auxiliary cooler to the current radiator cooler or by passing the radiator cooler and putting on a larger stand alone cooler.
I am looking to find the best bet for performance.

Tim

[obengston]

I have just went through this same thing. I had half say go through radiator then external, and the other half says go through the external only. I went through the radiator then to the external. They say if you go through the radiator it might heat it up. I really believe it will actually cool it down a little then to the external where it will cool more before returning to the tranny. If you have a stall like I do (3500) then the tranny fluid will be probably hotter then the radiator water because that side of the radiator has already went through the cooling cycle of the rad and waiting to return to engine. Just my opinion.

[H2Ogbodies]

To be honest, you need to run a tranny temp gauge whatever you do to verify your running temps for the tranny. I prefer to run from tranny to rad, then to an external filter, then to an aux. cooler and back to tranny. However, I also run my trans temp switch at the ext. filter and I use a PWM controller to keep trans temp @ 170 degrees +/-3 degrees with an electric fan on the aux. cooler. One idea for you is to come up with ways to increase system capacity to further extend the life of the trans. Deeper trans pan, aux. filter which also adds fluid capacity, an aux. cooler-all this can feasibly allow you to add about 3-4 quarts more of fluid which is a big advantage when fighting heat buildup in your trans. But you need to run about 165-175 temp range at normal operating range so you also don't want it too cool either. Do whatever you need to to run your trans temp at 20-25 degrees cooler than your engine temp and you'll do fine.

[JEFFTATE]

I plumbed the auxillary cooler before the radiator cooler on my wifes Dodge Ram ..
That way , the auxillary cooler would dissipate the bulk of the heat before the fluid went through stock cooler in the radiator..
And then when the fluid goes back through radiator part of the trans cooler , it kinda gets back to a 195 degree temperature ..
So the temperature isn't too cold in the winter ..

It seems to work well , I got 234,000 on the first transmission !

[John Wright]

What would be the MAX temp that you would want to see at the tranny?

I tow heavy(over 10K#) and I experienced nearly 280°F a few weeks ago when the ambient temp was 101°F and we had the A/C on pulling a 15% grade for miles at 30-35mph the whole way.

[jknight16]

Wow, 280 is really really hot for tranny fluid. I believe the generally accepted danger range starts at around 230.

[John Wright]

Wow, 280 is really really hot for tranny fluid. I believe the generally accepted danger range starts at around 230.So you're saying that fluid should be changed ASAP.
I got it cooled off on the other side of that mountain pretty quickly within a few miles it was back down below 200°F, also had more air going through the cooler and radiator when the speeds got back up on that downhill, which helped.

I have 120K+ on that truck...and I don't need to have a tranny bill at the moment.

[JEFFTATE]

My wifes Dodge Ram will turn on the MIL light ( check engine light) and the trans will go into limp mode ( no overdrive and no torque converter lock-up) if the trans fluid temperature gets 230 degrees or higher.
It has a temperature sensor in the transmission.
So , I guess 230 is pretty high ..