Hi guys. Anybody ever do any mods to their aux transmission cooler? Adding an additional cooler, a larger one, or installing a fan to blow on the cooler? I find with my truck when I'm stop/start driving in the city on a very hot day the transmission temp will rise to approx 220-250F indicated. When I get back on the highway it will cool down to approx 200F. On cooler days it seems fine. (I can't remember what it's called, but the transmission gauge temp sender is installed in what looks like a test port on the right hand side of the transmission. The guy from TST sent me a picture and told me to install it here). Any ideas or comments? Thanks.

 

When I get back on the highway it will cool down to approx 200F

That seems high to me, I would think that your gauge is reading wrong or you have other problems.

Floyd

 

First make sure the cooler isn't plugged up with bugs.

I didn't think any of the test ports on the RE tranny gave accurate readings although it would seem it they would error on the low side.
These trannys actually have an excellent cooling system, I would certainly double check that the the gauge is reading correctly before going any further.
Anything else you could do would cost many times what a gauge does.

 

Like has been said, the factory cooler is generally more than adequate.
To check actual cooler flow, remove rear cooler line at tranny. With engine running in neatral is must deliver a quart in 20 seconds or less. Catch carefully as very easy to make a mess. Don't run all fluid out of tranny.
Sensor location is accurate measure of tranny case temperature.

 

Does the fluid flow though the coolant heat-exchanger first or has that part been bypassed. If it flows through the exchanger first it should be entering the fluid-air exchanger at no more than the engine coolant temp; which is usually around 190 or less. I've seen people bypass the coolant exchanger is they have a leak and don't want to buy a new one.

 

Those are similiar temps to mine before and after my trans rebuild. Temps really climb in stop and go traffic. Usually no more than about 200 in stop and go. But it will climb higher if I let it. I usually pop it into nuetral or drop into a lower gear when going slower, seems to cool it down faster.

Cruising on the highway it goes to the 150 to 160 range depending on ambient. A pretty good rule of thumb for steady cruising is about 90 to 100 degrees higher than outside temps. The location of my temp sensor is about 16 inches out of the tranny on the line going from the tranny TO the heat exchanger (between trans and heat exchanger-the hottest point of the fluid)

I personally feel the cooler does not get adequate air flow when vehicle slows down. Just look at it's position. The fan can't even suck air through it based on it's location. I did purchase a 8 or 9 inch fan to mount if front of the trans cooler with a switch in the cab so I can turn it on when in stop and go traffic (especially when towing). It is a tight fit, and I did have to grind a little of the inside of the front grill for clearance, but you can't tell from the outside. I find the fan to be very usefull. I bought the fan on fleabay abut 3 year ago, about $25 bucks. Guess I got my $$ worth. It will lower things about 30 degrees and keeps the air flowing at slow speeds or when trying to park the 5th wheel in a tight spot.

I have read posts of guys installing another cooler under the cab, with a fan and a switch to do the exact same thing I have done but in a different location. If you add an additional cooler, you need to consider restriction or added resistence to flow. Not sure how much of a factor that would be, but the cooler lines are 1/2 OD, so I would not go any smaller than that.

Good luck, KD

 

hi
i have a truck which someone installed a larger cooler under the left side of the bed in adition to the factory cooler , it is app 9 x 24 " and has hyd hose running to it .
my temps do go up to app 200 at low speed / sitting ect , but drop to app 140 crusing in hot weather . no fan on the cooler .
also i spray it with gunk and hose it off then blow it out with air app 2 times a year .

 

Thanks for the info guys. I appreciate it!