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Proper Tranny Running Temp.

98XJLongBuild

98XJLongBuild

NAXJA Forum User
Location
San Jose, CA.
:firedevil Hey ya'll. i've got a 98 Cherokee sport with the automatic. I finally got my trany temp guage hooked up. My question is what is the normal operating temp.?
 
"The fluid life expectancy is directly related to the operating temperature of the transmission. Normal operating temperature is about 215 degrees Fahrenheit, but the cooling efficiency of you vehicle's cooling system and the type of driving you do will be the real determinate of it's life expectancy. At 215 degrees, it should go for 100,000 miles, but for each additional 20 degrees, the mileage is cut in half." Copied from QTS in Tempe, AZ.

However, different strokes for different folks--the automatic in a Dodge 3500 will tend to cook if operated for very long above 230 degrees--ask me how my FIL learned that lesson towing a large trailer loaded with salted beef hides through the mountains in August.

Here is a chart for transmission temps from TCI: http://www.tciauto.com/Products/TechInfo/trans_life_expectancy.asp
 
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My tranny temps in my 1998, I am hooked into the return line, using a stock Explorer tranny cooler in front of my condenser and radiator.
These are all in roughly 80-90 degree weather:
Cruising down the freeway at 70MPH, no more than 125
Stopped at a stoplight in the summer, creeps up to maybe 150
Crawling up a steep hill in 4wd low, maybe 180-220 depending on the size of the hill.
Usually not over 160 or so.
 
thanks to Joe mine only runs at the most 175 with stock trany cooler around town in 65 to 80 degrees outside.
 
Hey the weirdo thanks for that good info your setup is more advance than mine with the bigger tranny cooler and we still run around the same temps.
 
98XJLongBuild said:
:firedevil Hey ya'll. i've got a 98 Cherokee sport with the automatic. I finally got my trany temp guage hooked up. My question is what is the normal operating temp.?
Click to expand...

According to chrysler specs ....

The normal operating temp should be 122'f - 176'f

Since discovering that the factory provided, oil cooling system doesnt provide those temps - in my vehicle .... I'm making some changes.
 
I put my gauge sender in the FROM tranny line, flared end with a hose barb/clamps and all rubber lines from there. I no longer have quick disco fittings anywhere but right out of the tranny. The gauge sender has to be gronded on a metal line for proper reading (my sender is a "one wire" gauge and it's grounded from the metal line to the tranny.

trans001-1.jpg


Tiny picture, I know, but you get the idea.
 
3 of my 5 XJ's have the B&M tranny temp gauge on them and they all stay around 150-160 in the hazy, hot and humid summers here. I have never seen them run more than 180 even while towing or running rock.

I run the Hayden cooler that is made for RV's, I think they are 35,000 GVWR coolers and they cover about 1/3 of the radiator.
 
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Mine runs around 150 or 160 in normal driving, but it will run at 180 or so when pulling a good sized trailer. It will sometimes go up to over 200 for a brief period after down shifting for a grade, but it always comes back down pretty quickly.
 
winterbeater said:
Where would the best place be to put the gage sending unit? Wouldn't you want the tranny outlet line to be able to tell what the tranny is running at?
Click to expand...

I thought this too, but in looking at a couple of gauges, I noticed the Auto Meter instructions show it on the return from rad line. Where do most people put the sender?
 
hubs97xj said:
I thought this too, but in looking at a couple of gauges, I noticed the Auto Meter instructions show it on the return from rad line. Where do most people put the sender?
Click to expand...

On my trail rig it is in the pan, on the 2 street XJ's that I tow with it is in the return line from the cooler.

I get consistent readings from both places
 
hubs97xj said:
I thought this too, but in looking at a couple of gauges, I noticed the Auto Meter instructions show it on the return from rad line. Where do most people put the sender?
Click to expand...

My take on this is that I need to know what the operational heat of the transmission is, not the fluids post-cooling temperature. I can control the post-cooling temp, and by extension the pre-cooling temp, by adjusting the fluid cooling system to ensure that the operational temp stays in the safe zone, therefore the pre-cooling fluid temperature is the number to know.
 
I agree with the above post. Installing the sending unit on the return line from the cooler will not give you a good nor accurate reading. I brazed mine onto the oil pan on the passenger side near the rear. Mine is reading from 160 to 180 maybe 190 with the stock tranny cooler that is unfortunately now behind my winch with no air flow. But first seeing were it runs with the stock equipment then I'll install the B&M cooler that I got like a year ago. The only other question is which side to install it on, the passenger side were the motor fan is or on the driver side were the electric fan is??????
 
The best thing to do is to put 2 sending units on it and then a toggle switch between them. That way you can monitor real time how hot the tranny is and also if the cooler is working properly.

I used the return line because I want to know that the fluid going back in is cool enough to cool the tranny some. I know my tranny is getting hot on the trail or while towing.
 
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