i bought an external transmission cooler for my car and the transmission man suggested not using the original radiator trans cooler and just use the external one. i was thinking that running just the external cooler would keep the fluid to cold on cold days and hince bad for the transmission.


also, which line on a turbo 400 is the return line from the transcooler? top or bottom. thanks, gerald

 

 

On my Camaro I run the lines to both the radiator cooler and the aftermarket cooler itself, that's what it suggested on the B&M instructions. I can't remember which line is the return line on the TH400.

 

thats how i did it on my camaro too and my old truck. just cain't remember on the lines.

 

Top is return line on the TH400:
http://www.txchange.com/cooler.htm

 

thanks jordan

 

Unless we're referring to Siberian winters, an automatic transmission's fluid can't run too cool. Low fluid temps are life to an auto trans.

 

i was under the impression that a cold fiuid would hurt the transmission as bad as over heated fluid. i thought it cold run too cool and not be good for it. i read it somewhere, do not take it as i know for sure. just want the best way for my car.

 

I know this is an old thread, but FWIW, the shop where I brought my TH400 in for a rebuild strongly suggested I use the radiator cooler in conjunction with a (strictly) tranny cooler. The fluid routing is first to the radiator cooler, then to the tranny cooler and then to the return in the tranny. Again, FWIW.

 

I'm running an external cooler for my 400 and I'm bypassing the radiator. My trans cooler is HUGE thought. Prolly twice as long and 3x the thickness than the one you pictured.

 

I ran 2 tube and fin coolers (not as efficient as a double stack cooler) on my 73 Nova SS with a turbo 350 trans for 13 years exclusively outside of the radiator until 1990 when I sold the car with 170,000 miles on the original Turbo 350 trans through New England winters and hot summers! Never had an issue. I currently run a Long double stack cooler 28,000 GVW exclusively on my 2001 Pontiac grand Prix with 110,000 miles on the crap 4T65E FWD tranny and another Long Double stack 28,000 GVW cooler on my 1994 Mustang GT with the Ford AODE transmission-both do all the tranny cooler-no radiator cooling! I would fit the largest Double Stack cooler you can fit in the grille area of the C3 and run it outside of the radiator. You really cannot run the fluid too cool and I have given you 3 real world examples above where I have done the same with no issues-I have NEVER had a transmission failure on any of my cars with this method! The only issue with the 28,000 GVW cooler on the Grand Prix is that it takes about 2 miles for it to shift into overdrive in the dead of winter when it is really cold (0-20 degrees). Hope that helps!

Want the transmission to last forever? Run the biggest cooler you can outside of the radiator and change the tranny fluid and filter often-every 3 years or 20,000 miles for normal driving-more often if driven hard. Longer intervals if you use a full synthetic like I do in the Ford AODE-Mobil 1 ATF (very expensive!).

My 78 L-82 is a 4 speed!