Trans Temp Switch for Fan

[kewljay223]

Hey guys. Been a while since I posted anything here. Needing to do a lot of work to the truck very soon and one is to resolve a heating issue I have.

Quick back story.... I have a 95 rcsb with a 6-0 LQ9 swap with mild cam and a 4L80 upgrade (from stock 60e). I also have a Circle D 2800 stall. I feel it is a BIT too high of a stall for daily driving but man, does it launch nice....

Anyway, i also have a 5000lb boat that I tow around. Most of the time its local, and with the stall i obviously have to give a bit more gas to get moving but no biggie. The problem is on the longer trips through the desert going up a few long grades, the temps get up there. I had some coolant issues that caused some overheating and eventually took the trans out. had both trans and TC replaced.

I installed the tru-cool 40k and am now in the process of installing a gauge to monitor trans temps. I would also like to install 1 or 2 6inch fans on the cooler (pretty sure i have space) for those long grades in the summer desert heat just for security. My questions are:

1- Can I use an engine coolant temp switch to control the fans? Most are brass which I assume will be fine with trans fluid.
2- I only want the fan(s) to come on when it starts to get a little too warm for comfort and turn off when back in normal range. Will coolant switches work for this?

My main question is #2. Im afraid the "off" temp will hardly ever be reached and the fans will basically be ON most of the time. I suppose its better to have them on to help keep things cool, but it will also add to power draw for no reason and lessen the life of the fans. Is this a feasible idea or do I just need to have a manual switch to flip on and off while just monitoring the gauge? What temp ranges would suffice? are there any "transmission thermal switches" available? my research doesnt show anything trans specific.

Just trying to help prevent having to rebuild the trans again... That was not cheap, then again, I did put HD parts in it this time. haha

Also, please no comments about a stall and towing.... Ive already done enough research and talking to Circle D and others about this, and for what I have, its perfectly fine. Yes temps are higher and gas mileage goes down but im NOT towing the boat the majority of the time so that is the sacrifice I have decided to make. Thanks!

 

[df2x4]

What AUX cooler were you running when you overheated the other trans? I'd imagine the Tru-Cool 40K alone with no fans should be more than enough to keep the 80E cool. Especially if it's mounted in front of the radiator.

EDIT - Also just out of curiosity, are/were you using the built in cooler in the radiator?

 

[Supercharged111]

Sounds like your tune is the real problem, I tow way heavier than a boat and don't cook my transmissions. It doesn't matter what converter you have, if it's locked on the highway the trans will never get hot.

 

[kewljay223]

- the original cooler was a tube and fin style. This was done before I got the boat. This was also before I knew the differences between how they were made. haha

- yes it is mounted in front of the radiator and AC

- I never had a gauge hooked up to it so I honestly cant say what the temps got up to. But the fluid was dark and the internals were shot.

- You are correct that the tune is not correct. That is NOW after the cam swap. I have a fuel pressure issue at high RPM that the tuner stopped dyno because of. That is another thing on my list that will be resolved soon. But this would not have affected anything prior.

- The problem is not durring lock up. It is when going up a grade in 3 or 4 (no OD) for a decent amount of time. Because of the stall, there is a lot more slip which generates the heat that concerns me. again i have not had a gauge to confirm the temps, but the fluid color was a dead giveaway heat was an issue.

- yes i am using the internal radiator cooler. I should note however (which didnt occur to me when I posted this) is that I had the stock rad. After all that, I have since upgraded to all aluminum 2" 3 core rad. it also has trans and engine oil coolers built in. Also I had cheap ebay e-fans and have upgraded to SPAL's HD 16" fans which PULL some air.

so yea, i have done a ton of upgrades to the cooling system since the catastrophic failure. Its possible that I dont need fans on the trans cooler at this point, but from all the money i have spent to fix all that, im a bit paranoid.... a few extra bucks for some fans and relays are nothing at this point for insurance.

 

[df2x4]

Its possible that I dont need fans on the trans cooler at this point, but from all the money i have spent to fix all that, im a bit paranoid.... a few extra bucks for some fans and relays are nothing at this point for insurance.

True, but it's also more stuff that can break. It sounds to me like you've got your cooling issues covered this time around, I wouldn't worry about the fans if I were you. I like to keep things simple when possible.

If you do go through with it I'm curious to see what you find out about the temp switch, though. Don't think I've ever seen anyone run a temp switch in transmission fluid.

 

[kewljay223]

i agree. i may just install the gauge and drive to see where my temps are at and go from there. I hate just tearing into a project and skipping stuff just to come back later and do something i could have done prior.

Either way, it would be cool if someone who had any experience with a temp switch for trans fans could chime in. like you, i havnt seen anyone else with this but would like to know if its doable.