I had the stock cooler fail on me a while back, so ive installed 2 new coolers an 35000 GVW and a 26000 GVW. My question is what kind of tranny temp should I expect to see? I have the temp probe in the little port by the output lkine on my tranny and the guage reads 180 after a 30min 75 mph drive in 95 deg weather. Is that were it should be?

Thanks guys for the help, I have a little paranoia about the tranny after the stock cooler failed on me and now it slips from 2-3 often!

 

Are you towing when this happens?

180 is OK but, is your current tranny is slipping from 2-3....That might explain the quick build-up in temps, even with 2 coolers. IMO

 

No this is with the truck empty, The slipping may be the culprit! Thanks for the reply!

 

Install the temp probe in the cooler line exiting the transmission before entering the cooler.

That will give you a real time temperature and allow you to take evasive action before any real damage has occured.

 

Do you happen to know the difference between temps when probe is installed in the case vs the fluid outlet?

Just curious cuz mines in the case.

 

Lets look at this from a different perspective.

If the fluid is monitored as it exits the transmission and prior to entering the cooler after it has been put to work it will be a true temperature.
Let's say 180*. Which is getting border line serious.
At this time you can take evasive action.

If the probe is placed in the case the fluid will have been put to work, gone through the cooler and returned to the sump.

By the time this temperature shows the same 180* the fluid temperature exiting the transmission could be well over 250*.

Which is way too hot.
The only evasive action now will be from your pocket book.

 

Stuart I have my probe close to the exit line, and from my understanding its the output temp as well. So 180 is boarderline hot, What should I do to get this down? I'm using two large coolers and still getting the same results.

 

I have used old a/c condensors.
They fit across the entire radiator.

An external pusher fan is a good option too.

 

Thanks stuart1, Good point but I hope the difference is not that great. My tranny stays at 180-185 most of the time, towing or not.

I really wanted to know the if someone has actually had both temps checked at the same time to see the difference.

 

Check the routing of your transmission lines. It sounds like the lines are swapped to your radiator.

 

Does that make difference? I think it would if, there was a By-pass or Thermal Break in the line ie: a Thermostat, which returns the fluid back to the tranny without passing through the cooler.

 

Yes....

. If the transmission fluid is heating up to 180* empty this would be close to the coolant temperature.

The transmission fluid should come out of the transmission to into the radiator then thru the liquid to air heat exchanger.

What happens is when the transmission get replaced the fluid lines get reversed.
Then they blame the heating problem on the liquid to air heat exchanger and add larger coolers and they still get hi transmission fluid temps.

 

If you really are monitoring the fluid output and not the pan temperature then the only way to lower the temperature is to change your driving habits. Bigger and more efficient coolers will bring the fluid temperature down before it returns to the tranny but doesn't do anything to lower the temperature inside the working parts of the tranny.

A temperature of 180 isn't really serious if you are monitoring the output and not the pan. Optimum temperature is 175 or lower. If it stays at 180 all the time, just don't go longer than about 50,000 miles without changing the fluid.

If you are monitoring pan temperature then your 180 degrees is the temperature after you have cooled the fluid and the actual operating temperature is some number above that. What that number is can be difficult to calculate without knowing the efficiency of the cooler. And that efficiency changes with the outside temperature.

BTW, you don't have the cooler connected before the fluid goes into the radiator do you? If you do, you are cooling the fluid with the cooler and then heating it back up to radiator temperature before it goes to the tranny. The proper sequence is to connect the cooler to the output of the radiator. That way the radiator cools it down to the coolant temperature and then the cooler finishes bringing it down more.

 

In my case Zepcom Ive bypassed the radiator cooler alltogether, thats what failed on me and led to were I'm at now. What I cant understand is how I was using just a 26,000 cooler and was at 180, then added a 35,000 cooler and still am at 180? I was hoping for some drop in that number, but maybe I missed something?!

 

Did transmission fluid leak into your coolant?