Externals trans cooler
08-25-2017, 09:05 AM
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Year: 2000
Model: Cherokee
Engine: 4.0L
Externals trans cooler
Anyone have opinions or suggestions as to an External Transmission Cooler? I am pullin my AW4 to replace TC seal and Rear Main while I'm at it, but I've been hearing that these AW4s run hot, and I'm thinking about just going ahead and rebuilding the trans, 175,000 on it now, while I've got it out.
Is there benefit to having a trans cooler? Do I need one? Waste of time and money?
I have a 3.5 in lift and running 33s. So not to much extra tourqe being pulled from the trans.
Is there benefit to having a trans cooler? Do I need one? Waste of time and money?
I have a 3.5 in lift and running 33s. So not to much extra tourqe being pulled from the trans.
08-25-2017, 09:10 AM
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Year: 1990
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33s are the commonly accepted threshold that a cooler is needed. I wouldn't waste the money rebuilding the trans if it is operating correctly. I have 235k on my 90 with 33s and the trans still shifts good. I have a temp gauge installed on the trans and have seen the temp get up to 200 w/ an external cooler in soft sand. I can only imagine what the temp would climb to without the cooler.
08-25-2017, 10:10 AM
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Year: 2000
Model: Cherokee (XJ)
Engine: 4.0 L6
What gearing are you running with your 33s?
IMO, an aux cooler is cheap insurance for any XJ. The AW4 is a solid transmission, but keep in mind that for roughly every 20 degree increase in temperature over 175 degrees, the life of transmission fluid is cut in half.
Fluid life:
175 degrees: 100,000 miles
195 degrees: 50,000 miles
220 degrees: 20,000 miles
At 200 degrees operating temperature, it won't take long for fluid changes to add up to the price of a junkyard cooler, and mounting one is simple.
IMO, an aux cooler is cheap insurance for any XJ. The AW4 is a solid transmission, but keep in mind that for roughly every 20 degree increase in temperature over 175 degrees, the life of transmission fluid is cut in half.
Fluid life:
175 degrees: 100,000 miles
195 degrees: 50,000 miles
220 degrees: 20,000 miles
At 200 degrees operating temperature, it won't take long for fluid changes to add up to the price of a junkyard cooler, and mounting one is simple.
Last edited by Tbone289; 08-25-2017 at 10:22 AM.
08-25-2017, 11:54 AM
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Thanks for the replies guys. Sounds like the best idea would be to get a gauge and run it for a while on and just check temps. I know these AW4 were built to run around the 200 mark. I've been using Dex/Merc 3, I believe and it has never given me any trouble. I had a fly wheel break beginning of the year and drop the trans to replace it, got it all back together and had a major leak coming from the inspection plate area. I'm thinking it's the seal in between the TC and the Trans.
I will think about a cooler and see if I feel like I'll need one. I am leaning more towards no. But thanks for the info!
I will think about a cooler and see if I feel like I'll need one. I am leaning more towards no. But thanks for the info!
08-25-2017, 12:30 PM
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If you add a gauge, I recommend you add it on the transmission output line before the cooler. Many people install them after the cooler and never know what maximum temperature the fluid is reaching.
Last edited by Tbone289; 08-25-2017 at 12:35 PM.
08-25-2017, 09:08 PM
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Year: 1990
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Depending on what year you have, the below should help install the temp gauge. I installed my temp sensor just like the below and it works well.
This is not a How To post. Just some data for those interested in installing a temperature sensor for a temp gauge to monitor their AW4 fluid temperature.
This data applies to AW4 transmissions up to 1997. AW4 transmissions, starting in 1998, had the transmission case redesigned to accomodate an Input Speed Sensor, and in the process deleted the port described below.
The A340 transmission had/has a port on the transmission for a temperature sensor installation (see pic below). The pre-1998 AW4 transmissions has the same port but was not used for a temp sensor in the Jeep installations.
Page from a Toyota Tacoma manual showing the temp sensor location:
Attachment 324818
The temp sensor port blanked out on a '98+ AW4:
Attachment 324819
Temp sensor port plug incorporated in the pre-'98 AW4:
Attachment 324820
Temp sensor Metric adaptor for installation of a temp sensor:
Attachment 324821
Installation of the Metric adaptor and the temp sensor:
Attachment 324822
Pic of the temp sensor installation is from a thread on NAXJA.
This data applies to AW4 transmissions up to 1997. AW4 transmissions, starting in 1998, had the transmission case redesigned to accomodate an Input Speed Sensor, and in the process deleted the port described below.
The A340 transmission had/has a port on the transmission for a temperature sensor installation (see pic below). The pre-1998 AW4 transmissions has the same port but was not used for a temp sensor in the Jeep installations.
Page from a Toyota Tacoma manual showing the temp sensor location:
Attachment 324818
The temp sensor port blanked out on a '98+ AW4:
Attachment 324819
Temp sensor port plug incorporated in the pre-'98 AW4:
Attachment 324820
Temp sensor Metric adaptor for installation of a temp sensor:
Attachment 324821
Installation of the Metric adaptor and the temp sensor:
Attachment 324822
Pic of the temp sensor installation is from a thread on NAXJA.
08-26-2017, 03:03 AM
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Engine: 4.0 I6
Honestly, its doubtful that your AW4 would be too cold pushing 33's with presumably stock gearing.
Just make sure you get a bar & plate cooler at a minimum. This would probably be an appropriate size
Or you can get one from a Junkyard, lots of Chevy's have good ones from the factory
Just make sure you get a bar & plate cooler at a minimum. This would probably be an appropriate size
Or you can get one from a Junkyard, lots of Chevy's have good ones from the factory