FrankGRUN

I've been fighting a coolant overheating problem that occurred pulling a long grade with 33's and the stock 3.55 gears with an AW4 automatic. At first, I assumed it was brought on by running up the grade in overdrive with the wrong gears thereby generating lots of heat in the trans and overwhelming the cooling system. So I regard to 4.56:1 and kept the 33's. The temps dropped about 10 degrees but I quickly got up to 235F if I didn't back off the throttle and downshift to 3rd. I then installed a temperature gauge with the sender mounted in the trans pressure testing port.

Immediately I start seeing outrageous trans fluid temps. After a few minutes of warmup, the temperature hits 160 then rises quickly to 220. From thereon it climbs (in regular highway driving) to 280F in about 30 minutes. If I take on a 1-2 mile long grade, the temperature runs right up to 300F. But if I then stop with engine running and use a handheld IR thermometer to measure the temp of the stock auxiliary trans cooler mounted in front of the A/C condenser and radiator, I measure 160F! This while the trans temp gauge is still indicating 300F.

I'm confused! This seems to suggest clogged trans cooler or cooler lines. Reading the many threads on the forum, a faulty lock-up solenoid is also suggested. Any wisdom, experience or suggestions would be greatly appreciated!

XJlimitedx99

Is your gauge on the output of the trans or the cooler?

FrankGRUN

The gauge sender is mounted in the transmission pressure test port which is next to and just above the fluid out coolant line. This location is supposed to sample the fluid just before it exits the trans on the way to the radiator cooler exchanger. In this 96 XJ the trans fluid goes from the trans to the radiator then to a thin and small auxiliary air-to-air cooler in front of the radiator and then back to the trans.

bryweb

I overheated my daughters bad once over loading it towing (another Cherokee in Stop and Go), once overheated I had issues with it overheating just going down the road at 70mph after 20 minutes and spewing fluid out the front pump seal (before I towed small trailers from Florida to Chicago and back at 80mph no problem) I tried to flush it, changed the front pump, and did a bunch of other things until I finally just through in a junkyard transmission.

I had a trans guy said that once I over heated it the 3rd gear clutches were probably slipping causing a lot of heat and that was the issue.

Also on my current build I have a guy building me a new transmission (beta tester for a shift modification kit they are designing) and he said something about some design flaws in the valve body that cause the AW4 to overheat that he was going to take care of while in the trans, that and this time I am definitely going with trans temp gauge and trans cooler.

FrankGRUN

Just checked the transmission fluid color and its red with no burnt aroma.