My 97 XJ has the factory transmission cooler. In 65+ temps sitting in traffic the coolant gauge is generally closer to one mark after 210. The fins on the tranny cooler are also banged up from having been on the Jeep for 18 years/200,000 so I'm not sure what its doing to airflow. I am thinking of deleting it altogether at least as an experiment. That would get heat away from the front of the radiator and also improve airflow. My 01 XJ has basically the same age and parts for cooling system, but does not have a tranny cooler. I don't think I've seen it go one or two needle widths over 210. Wondering what others experience when they put auxiliary coolers in front of the radiator.
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what does a transmission cooler do to coolant temperatures?
- Thread starter md21722
- Start date
I have a auxiliary cooler on the front of my '89. Still running it through the rad. The fluid comes from the trans through the rad then through the aux cooler, back to the trans. Depending on how big the aux cooler is will determine the cooling effect. Mine is 4 passes. I don't have a temp gauge on the trans fluid but my guess is about 10* after the auxiliary. it's good to have the trans be warmed up by the rad. Having the trans fluid too cold is not healthy for the trans. My coolant rarely gets past 210*
- Location
- WA state
Well, stock gauge are notorious for reading incorrect. Need to confirm what the actual water temp is on both vehicles. I know that my gauge reads ~10 deg hotter than actual temp. The cooling system runs hotter than the trans fluid. And I would think a trans cooler would help offset that, otherwise what would the point of a trans cooler be?
Also, what have you done to your cooling systems as far as maintenance, replacement etc? A properly maintained stock setup should be more than adequate for daily driving.
Also, what have you done to your cooling systems as far as maintenance, replacement etc? A properly maintained stock setup should be more than adequate for daily driving.
On my 97 XJ, I've had the scanner up to it and when it said 212, it was right there just a hair over 210 so I believe its correct.
Both cooling systems are in the same condition, the 01 XJ roughly 6 months older. All new parts from the same places on each. Radiators replaced with Auto Zone Spectras because they were weeping from the plastic joints, dealer water pumps & hoses, and NAPA fan clutch.
Both cooling systems are in the same condition, the 01 XJ roughly 6 months older. All new parts from the same places on each. Radiators replaced with Auto Zone Spectras because they were weeping from the plastic joints, dealer water pumps & hoses, and NAPA fan clutch.
- Location
- Golden, CO
Although my jeep is a different model-year, with a different cooling system, installing the (factory) auxiliary cooler to my transmission circuit had no effect on the engine temp gauge.
jrowell
NAXJA Forum User
- Location
- Bakersfield
Same here (although I added an aftermarket cooler)... and made my AC not blow cold. considering removing mine.
lazyxj
NAXJA Member #1310
- Location
- Los Angeles
R.DesJardin
NAXJA Forum User
- Location
- Clarkston, WA
Transmission coolers should be installed before the radiator. This way the transmission fluid is supplied at a consistent temperature. Very important for long auto trans life. This also will help reduce extra heat put into the engine cooling system. I run a kick ass fan on my trans cooler.
- Location
- WA state
lazyxj
NAXJA Member #1310
- Location
- Los Angeles
The gauge indicates the temperature sensor's output.
If the sensor is out of calibration, the gauge will indicate the wrong temperature, a common occurrence.
Where ever the cooler is installed, the extra surface area will help keep the drivetrain cool.
If you are concerned about overcooling the trans oil, install an inline thermostat that bypasses the cooler, until the oil warms up.
http://www.amazon.com/gp/product/B0..._m=ATVPDKIKX0DER&pf_rd_r=09F378S1CWNWEJCYF4TJ
Stopped by HF and the IR thermometers were on sale for $36. It looks like HD or Lowes are cheaper for the IR thermometers. I have an older one from HD but I don't trust it. If I put the thermometer on the thermostat housing neck between the heater supply and temp gauge I get around 218F. If I point the laser at that spot from about 6" away it reads 190. The temp gauge reads 210.
After looking at the cooling system some more, I think a previous owner used 2 of our favorite words, stop leak. I am getting this fine grit in the coolant reservoir and in the radiator neck under the cap there has been another gritty substance, grayish brown in color when put on a shop towel. Some of it comes out with a magnetic pick up tool. I have never seen anything like it, but I have never owned a car where stop leak was used before. I am going to see about cleaning out the cooling system before I spend any more time with the transmission cooler.
lazyxj
NAXJA Member #1310
- Location
- Los Angeles
It's most likely left over casting sand that remains from when it was originally cast.
I found quite a bit of it behind a rotted freeze plug, at the rear of my XJ's engine.
tonytech
NAXJA Forum User
- Location
- Las Vegas, Nevada, USA
It cools the heated fluid generated by the vehicle's transmission system.
yossarian19
NAXJA Forum User
- Location
- Grass Valley, CA
My '98 had the factory trans cooler as well. It ran at 210, all day every day. The trans cooler isn't your problem: the factory designed it with towing in mind and I know from experience that they didn't muck it up so badly as to make the engine run hotter.
If the engine is running warmer while sitting in traffic (but at 210 or under while cruising flat highway) I'd suspect a weak fan clutch.
Also possible the fins of your radiator / AC condenser are banged up and blocking airflow, but the trans cooler isn't large enough to make a ton of difference to the AC / Rad. airflow.
The fan clutch was replaced along with the water pump, radiator, radiator hoses, radiator cap, and thermostat. Dealer water pump, thermostat & hoses. Auto Zone radiator. NAPA fan clutch and radiator cap. Same parts as my 01 XJ which was refreshed a couple of months earlier than the 97 XJ I'm asking about. The 01 XJ also got a new condenser and never had an auxiliary transmission cooler.
After more investigation, my IR thermometer seems to read about 7-13 degrees lower than 97 XJ dash gauge at various temperatures. Ohm for ohm against the chart, and also comparing against an ODBII scanner, the dash gauge seems to read what the sensor says.
Unsure of whether or not my IR thermometer or my temp sensor is introducing the error, I went out and compared against my 01 XJ. The IR thermometer, dash gauge, and sensor all agree within 3-5 degrees on the 01 XJ so my conclusion is that the 97 XJ temp sensor reads a bit high.
After more investigation, my IR thermometer seems to read about 7-13 degrees lower than 97 XJ dash gauge at various temperatures. Ohm for ohm against the chart, and also comparing against an ODBII scanner, the dash gauge seems to read what the sensor says.
Unsure of whether or not my IR thermometer or my temp sensor is introducing the error, I went out and compared against my 01 XJ. The IR thermometer, dash gauge, and sensor all agree within 3-5 degrees on the 01 XJ so my conclusion is that the 97 XJ temp sensor reads a bit high.
