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Help! 98 4x4 transmission leaking fluid near output cooler line
1998 Durango 5.2 4x4.
Truck was leaking fluid at an aggressive pace and seems the output cooler line had corroded and was leaking. I replaced both transmission cooler lines, topped off fluid, took it for a test drive to get up to temp, chocked wheels, placed in neutral on level ground, rechecked and topped off transmission fluid. Everything appeared great, except to my surprise there was a puddle of fluid under the transmission. Puddle is about the size of a large dinner plate after only a few minutes running.
It does not seem to be the lines leaking. From what I can see it appears to be coming from near the output cooler line fitting on the driver side near rear of transmission. It only leaks when vehicle is running and in neutral. Running in park does not leak, so it only happens when the transmission fluid is under pressure.
I cannot tell if there is a crack or if that is a casting seam near the midline of the cooler line connection, but the fluid actually appears to be coming from higher up above that. The output cooler line attaches to a brass flare fitting, which did come out when I unscrewed the old line. I separated and reinstalled the brass flare adapter. I have a hard time believing I cracked the housing by overtightening the brass flare fitting. Seems more likely I would have just stripped the brass threads.
Assuming I am correct it's higher up above the cooler line fitting, it almost appears to be coming from between the seam between the main transmission body and the tail housing (or whatever we call the section between the main body and the transfer case). I did some searching and saw some posts about a transmission pump vent that is on the top of the transmission, but I'm not familiar with this, and it's not easy to get a good look above this point while the transmission is installed.
Get a bright flashlight, a mirror, and a friend. Crawl under there, and with your bright flashlight, and mirror, see if you can see further above the fitting. Have your friend start the truck, put it in neutral, and see if you can find the source of the fluid. Being able to put it up on a host would be nice, but, I know that's not an option for everyone.
I confirmed this is a crack in the housing caused by overtightening the line adapter. I didn't reef on it, but seems I should have put another wrench on the flare adapter to counter the force of tightening the cooler line fitting.
This is apparently common enough there is a specific repair kit Sonnax 22000-01K that included a tap and a special adapter fitting that bottoms out in the transmission case to form a seal at the nose of fitting. https://www.sonnax.com/parts/1816-co...ine-repair-kit
A common complaint in late-model Chrysler rear-wheel-drive units is a cracked and/or leaking case caused by installing the cooler lines. The tapered threads and the lack of a stop on the OE cooler line fitting can load the case and create a fracture, resulting in leakage that may require replacing the case. Sonnax cooler line repair kit 22000-01K features adapters that seal on the leading edge, preventing fluid from reaching the fitting threads and crack. The fitting has straight, not tapered threads to prevent the crack from spreading.
I confirmed this is a crack in the housing caused by overtightening the line adapter. I didn't reef on it, but seems I should have put another wrench on the flare adapter to counter the force of tightening the cooler line fitting.
This is apparently common enough there is a specific repair kit Sonnax 22000-01K that included a tap and a special adapter fitting that bottoms out in the transmission case to form a seal at the nose of fitting. https://www.sonnax.com/parts/1816-co...ine-repair-kit
So that kit solved your leak, no? Thanks for being one of few people that actually comes back with what fixed it by the way, most just are a one post wonder these days.
11-16-2021, 05:12 PM
Help! 98 4x4 transmission leaking fluid near output cooler line
Thank you for the info.
