Th-350 Trans Cooler Routing

[Dodge68charger]

What Is The Correct Way To Route The Lines To a Transmission Cooler?

I See Different Variations On The Web..

Not Sure Which Line Is In or Out On a Th 350. Thank You
Posted via Mobile Device

[my67c20]

I bought this from inline tube and for the most part it fit pretty good. With shipping it was like $110.

SCTT6701 1967-70 Chevrolet/GMC Truck 2WD T350 5/16" Trans Cooler Lines 2pc, Stainless

[Dodge68charger]

Thank You. Not Sure What Line Goes To The Top Of the Radiator Then To The Top Or Bottom Of The Cooler?

[siggyfreud]

I've usually run top-to-top, and bottom-to-bottom, but I don't believe it matters ultimately. The fluid can flow both ways.

[mrein3]

Originally Posted by Dodge68charger

What Is The Correct Way To Route The Lines To a Transmission Cooler?

I See Different Variations On The Web..

Not Sure Which Line Is In or Out On a Th 350. Thank You
Posted via Mobile Device

Good question and it does matter which way you route the external cooler.

Here in Minnesota, where temps are about to drop off the table, you need to HEAT your transmission fluid. In other words you run the hot fluid out of the transmission, into the external cooler, then to the "cooler" in the radiator, then back to the transmission.

I hot climates, run it from the transmission, to the tank in the radiator, then to the external cooler, then back to the transmission.

I knew a guy here in MN that ran it the second way in the summer and switched it in the winter. He had all these ball valves and pipes/hoses set up to "make it easy".

I ran mine the first way about 15 years ago and haven't looked back.

I also installed a trans temp gauge. Pulling my boat in the worst summer heat I see 210 max on the gauge.

[Andy4639]

The transmission doesn't care which way you run it. The goal is to keep the temepature below 200* no matter what the vehicle is doing.


200 degrees Fahrenheit
The general rule is to keep the transmission fluid at or below 200 degrees Fahrenheit.
The ideal operating temperature of transmission fluid is 175 degrees. Overheating occurs after the temperature surpasses 200 degrees, and the failure rate doubles for every additional 20 degree increase after that.

[my67c20]

The kit is prebent, so it would be hard to screw it up.

[Dodge68charger]

Going From The Bottom ( Hot Port ) Of The TH-350 To The Bottom Port Of The B&M External Cooler..

From The Top Line Of The Cooler To The Bottom Port Of The Radiator..

Then From The Top Port Of The Radiator Back To The Top Port ( Cooler) Of The Transmission..

Think It Would Help Push The Air Out..

[siggyfreud]

Your original post didn't state you were going to an external cooler and no idea how mrein3 intuited that . . .

[Andy4639]

I always go to the lower fitting first as stated to keep air out and on first start up pushes it all out. I go to the radiator first then the external. Outside temperatures are never that cold here in SC to make any differences to the way you route it though.

[mrein3]

Originally Posted by siggyfreud

Your original post didn't state you were going to an external cooler and no idea how mrein3 intuited that . . .

Yes I see that now. You can't screw up hard lines. I assumed they were adding an external cooler because you can't screw it up with the factory tank.