transmission Temperature

[cwsoules]

In rolling terain when towing at 60 mph in OD my transmission runs at about 170 F. In town at low speeds after being on the road for some time it will come up to the low 200's.



My problem is backing. After just a few (less than ten minutes) I see it at 240 F. When backing into our current location in Gettysburg it got up to 260 F as I had to avoid trees and back up a steep grade. I even stopped for a few minutes and with the brake set and the transmission in neutral I tried to cool the transmission by spraying water out of a hose onto the transmission cooler. I was surprised that I did not see a drop in temperature within a few minutes (less than 5).



I have the Dodge tow package with the extra cooler that in installed as part of the package. Perhaps I need more. I do have an enlarged sump pan. Should I have sprayed the water on the pan?



How to you guys keep your transmission temp down?

 

[BK]

my transmission guy told me that the only thing reverse was ever designed for was backing out of or into a driveway.



Also with the low speed, there was also only minor airflow under the hood and very little through the transmission cooler. Lots of TC slippage... lots of heat build up... .



I think the cool (pun ment) thing todo (besides replacing the TC with a more efficent one) is to put an electric cooling fan on the transmission cooler.



This is another place the Horton fan would probably come in handing... if the temps at the clutch fan just weren't high enough, it maynot have been engaged well enough to get a nice amount of air flowing. With the Horton, you can overide and make it completely lock up (from what I remember reading. . dont have one) and will move much more air at idle and low RPM than the stock fan/clutch assy.



Also engine temp as a lot to do with it too... so as the under the hood temp was rising and heat gets stored in the radiator but doesnt get disappated well at low speeds, it all helps to raise the transmission temp or just keep it up there. Opening the hood would have been a good thing. It's something we do after running/towing on the beach at 5mph... with all that load and torque, things cool down dramaticly quicker with the hood open. . even out on the hot summer time beach. The heat wants to rise. With out force the hot air down by forced air flow, the hot air stalls at the top of the hood, I don't see that the fan , at idle, can overcome the stalled air and force it down out the bottom of the truck... . but at highway speeds it works fine. The engine is a large thermal mass, with little air flow through the engine capartment, the heat will tend to conduct to the transmission. The transmission is aluminum which conducts heat fairly well and quickly.



At times of real criticle heat build up I've had with some gassers when towing off road. . I"ve put the cab heaters on. I've seen some high HP gassers even add an aux electric fan next to the block facing down to help get the air flowing at low speed.



Could add louvers to your hood?



I've never seen it, but the theory is right. . if you spray enough cold water fast enough on that hot pan, you could crack it. . or crack the transmission housing.

 

[chuck3]

You might try the Mag-Hytec deep pan, I found it lowered mine by about 25 deg. in town or on the road.

 

[Gary - K7GLD]

I have the double-deep Mag-hytec transmission pan on my 727 - does reduce the temps in short spurts of transmission stress, but won't make a noticeable difference in the down-and-dirty long hard pulls... Still, can't hurt to have that extra gallon of transmission fluid down there working for you, and to help absorb extra heat. 260 is getting up there in temp - but I've got my temp guage right outside the torque converter in the outgoing cooling line - and on a REAL bad grade last year, pegged the dern thing (probably well over 300 degrees!) and wiped it out! The fluid was still OK judging by look and smell, and it was just yesterday that I drained the transmission pan and replaced the guage.

 

[Eric_77]

unless they moved the transmission cooler on my 96 there is no way that the fan sucks any air through it. It is mounted so far out board I have thought of a couple of tricks.

1. add a second cooler that mounts in front of Ac condenser with a temp controller switch to flow only in high temp needs.

2. collect the water dripping from AC evaporator and then have switch that will spray it on cooler when needed.

 

[BK]

one can take on of the small pusher electric fans and add it to the front of the transmission cooler. . could use a temp switch on the transmission line to activate it an during the slow crawls and trail spotting session use an over ride switch to be ahead of the game

 

[Gary - K7GLD]

YER only gonna get the fluid temp SO low, regardless of HOW many fans or coolers ya add - the REAL problem is the heat generated in the transmission and TC BEFORE the fluid gets TO the cooling devices! Eliminate/reduce slippage in the transmission itself, and the OTHER issues will be greatly reduced!



Don't get me wrong, extra coolers are GREAT - but yer only treating the SYMPTOM, not the CAUSE!

 

[cwsoules]

I can see I need to upgrade my profile as my truck doies have a Mag HY-TECK 727DD Pan.



When I sprayed water on the truck it was only onto the radiator in an attempt to cool the transmission.



It seems strange that a truck supposedly designed as a work horse, can not back up for more than a few minutes without over heating the transmission. When I worked on a farm we expected our powered machine to be capable of backing up even when towing a load.



The auxiliary fans described in the replies to my post sound like they may be the solution to my problem. Can anyone tell me where I can find them?

 

[BK]

http://www.flex-a-lite.com/auto/appguide.htm



And summit racing, who's on line too and you can buy from on line.

http://www.summitracing.com/



re: your comments about the work truck/overheating...

I understand your comment.

I also see that Dodge has tried to cater to a crowd that wants a more lush truck. . softer shifts. . mushier suspension... .

Things that tend to get away from the heratige and background that made the p/u the work truck of the common man.



There is one thread I read from a Ford owner, he's been through three auto trannies allready because of the distance & grade he has to back his trailer up on his driveway!



And now reading your tagline. . I see you already have a DTT TC and VB and EZ... well your in the middle of building your own truck todo what you need it to do. I would have thought with the DTT tc, you would have been better off already.



But there's more to it , IMHO than just the transmission... based on my experience towing off road at very low speeds and high torque.

Getting the heat out from under the hood is a biggy. .

For every 10 degrees hotter the engine runs (remember thats just based on the water temp), the transmission can see 20 - 30 degs more. Temps from the exhaust manifold are being vented when your running soo slow. Heat wants to rise... . it wont find it's way out from under the frame rails by itself at slow speeds.

 

[redramnc]

Torque converter apparently makes a big difference. I have a 78 W200 with a built 360 gas, headers, cam, etc. and one of the old A-1 "tow" converters in it. I have never seen the trans temp over 200 even with shoving a loaded gooseneck around backwards in the mud. I have pulled stumps with the beast and snaked logs in the heat of summer. My brother has the same truck except it is an ex-military truck, stock engine, trans and TC, same 4. 11 gears and his trans gets alot hotter than mine. Only difference I can point to is that mine has a deep pan and TC that his doesn't.



My TC is much tighter than his. That is only thing I can contribute the heat to.

 

[Gary - K7GLD]

"My TC is much tighter than his. That is only thing I can contribute the heat to. "



MY point exactly! You can only do SO MUCH with external cooling - eventually, if problems persist, ya gotta dig into the REAL cause!

 

[PHaller]

The problem here is the gearing in reverse. It's high... about halve way between 1st and second in forward gears. IMHO, the 727 transmission and its decendents should stay where they were intended to go. Behind a 440 Cuda or Challenger that makes big power at 5000 rpm and not likely to back anything but itself into a garage.

-Paul R. Haller-

 

[RedRamer]

I read somewhere that the Transgo shift kit keeps the TC full in Park and while backing up with a heavy load.

Maybe with the stock transmission this slushing arround in a partly filled TC in reverse is raising the temps a lot.

I get those high temps fast in reverse also with the stock transmission.