Lets see what our trans guys here think. I'm adding a small external trans cooler to my truck. The truck is a 99 GMC sonoma 4.3L ext cab 2wd with the 4l60. I use the truck to tow the vette a couple times a year and believe it or not it does very very well. I also use an alum featherlite trailer with elec brakes. My question is placement in the loop. I can put it in series with the stock cooler in the radiator before the stock cooler or after, or I can bypass the radiator all-together.
1: Bypass the radiator. This would eliminate the heating effect from the stock cooler but in cold weather would it cause other issues like the trans not getting up to temp quickly enough or at all causeing it to not shift into OD.
2: Post radiator, see above. Would it cause the same problems in very cold weather?
3: Pre radiator. Would this even drop it down enough to be effective? I'd think that it would cool the fluid but the fluid would then pass through the stock radiator cooler and thus reheat it.


Discuss

The cold side of the radiator is much colder than you think, probably 30-40F lower than the tstat temp.

But.. it's actually important to keep that in the loop since it helps bring the tranny fluid up to temp.

I would put it in series. The temp difference of the radiator cooler isn't as much, but liquid/liquid coolers are VERY efficient, which is why they're so small.

I suppose you're putting in a guage too right? Maybe you should do that first and see where its at before doing anything else. They also have billet aluminum heat sink pans, not sure how much that'd help, but Nissan did just that to cure the overheating on their Titan pickup rearends.

I was trying to find a tranny cooler writeup at bowtieoverdrives.com that goes into the details but I can't find it.

No temp guage yet. I think that most people are in agreement that in series and prior to the radiator is the best way to go. Anything will be an improvement. I've not had any issues with it, I just want to prolong the life of the trans and help it tow. I hope I didnt just jinx myself.


FWIW, I just got through installing an electric fan set up on the truck tonight. I did away with the belt driven setup completely. Works like a charm and maybe frees up a bit of HP.

BEST WAY TO PROLONG THE LIFE OF YOUR TRANS IS TO SERVICE IT REGULARLY & IF YOU TOW WITH IT USE SYNTHETIC ATF...THAT IS WHAT I USE IN MY GMC & WE PULL HEAVY HEAVY CRAP ALL THE TIME & HAVE HAD 0 PROBLEMS WITH IT...THE TRUCK HAS 182K ON IT

SORRY DR.....I AGREE WITH CENTRAL...IN SERIES BEFORE THE RADIATOR IS PERFECT