Cracked Transmission Housing at Cooler Fitting

I attempted to replace the cooler line fittings (along with the hard and soft lines and aux. cooler) on my 1996 Jeep Grand Cherokee 4.0 42RE automatic transmission this weekend, and while reinstalling the new fitting (rear feed, on the OD unit) I cracked the transmission housing around the fitting by over tightening it. From what I gather it is a common mistake/problem, as there was no greater turning resistance since there no stop for the fitting. I was using a 6" adjustable wrench and turning it with 1 finger. I had the wrench vertically above the fitting right near the TV cable spring(?) and was not cranking down on it at all. Seriously turning it with one finger, 1/8 of a turn at a time. That’s all I could do in that tight space. Well that was enough torque to split the aluminum transmission case along the casting mark. After some googling I think found a solution - Sonnax part #22000-01.

Does any one have experience using this repair kit Sonnax part #22000-01K? The instructions say to tap the hole until the tap bottoms out. Will that be obvious? Then It says to visually look for contact witness marks inside the opening. I’m not sure I can see into it, its tucked up into the transmission tunnel, should I use a mirror?
The fitting is going to be arriving this afternoon., and I’m just looking for any input to make this repair as painless as possible.

Interesting. The repair seems fairly straight forward if you have reasonable access. The important part seems to be making sure the tap bottoms out so that there is a good surface for the adapter and then test fitting it to make sure the adapter has a good seal. I guess I would use a little grease on the tap to catch any metal filings from the tap and then maybe use a Q tip or something to make sure there are no metal filings. That type of tap though is designed to bottom out in a blind hole though. You need the tool for the tap though and clearance. Poor design.

I have a can of CRC cutting oil (which is really sticky stuff!) and will be flushing out the cooler line before attaching it to the cooler, so hopefully I will get any shavings out that way.

Thanks for the input Bing!

This might be a good opportunity to buy one of those vdo inspection cameras. Sometimes called a bore hole camera I think. You know, the kind with the long flexible tube you can maneuver into position, while you watch what it is showing on a little tv camera. Inexpensive versions are available for less than $100 I think.

If the housing around the threads cracked that isnt pleasant…but it might not be the end of the world. As long as the nose of the fitting is held in place with enough force. Now if this crack is serious enough to not allow proper torque that is another story entirely. You might be able to simply thread lock the threads in place and leave well enough alone…as long as it doesnt leak.

I tried to see a picture of the products you listed but they led nowhere…I also tried to see the trans fitting

As far as drilling and tapping… You will know when the tap bottoms out…it pretty much stops dead and the “feel” of the tap changes significantly. You should know when you get there…

From what it sounds like…you are trying to “Helicoil” the thread perhaps? If so…they work great and are actually stronger than the original material in most cases.

I could be of much more assistance if I had a pic of what you are facing…I do repairs like this more often than I would like and have developed many ways around these types of things with great success.


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Seriously turning it with one finger, 1/8 of a turn at a time. That's all I could do in that tight space.

I’m curious how do you expect to fit a tap in there? Not only does it stick out substantially compared to a flat wrench, but you need to get it started in the threads properly before you begin tapping away the tapered threads of the pipe thread in there now…

I sympathize with the frustration of using an adjustable wrench, 1/8 turn at a time. I’m going to suggest you think about buying a set of gear wrenches. Just one use like this and they’ll pay for themselves in stress reduction alone…

Thanks for all the replies everyone here is a good link to the product I used.

I’m glad to report everything went to plan and no leaks so far. I had removed some of the JB weld around the fitting and exposed the front face of the crack so I could make sure it wasn’t weeping at all. The locktite bubbled a little on the crack initially when it was idling in neutral, but after another 1/4 turn it seems to have sealed.

I was able to use a soldering iron to get the JB weld off. It actually worked great. It basically would just crumble away after it was heated.

The threaded opening is tilted down slightly and with the grease on the tap I was able to get virtually all the metal shavings so I don’t think there is much of a risk of any getting inside. I cleaned the tap and packed it with fresh grease about a half dozen times

I couldn’t really see any witness marks as the instructions noted on the fitting or on the threads in the case, so I put a little bit of grease on the very end of the fitting and tried again, and I could see the contact area on the fitting and see a ring of grease inside the case. I’ll keep you guys posted, but I think it’s good to go

Hey how can i send a picture of what i have going on its nothing major its a 99 lexus gs300 automatic transmission and my oil coller line was leaking pretty bad so i tightened it and when I tightened it i noticed i stripped it so i just turned it on to chck if it would leak and it just started to leak really heavy so i know i did something wrong and so I attempted to take the crew out and than i noticed two cracks one at 12:00position and other at about 2:45 to 3:00 position if it was a clock(hopefully u know what i mean) i noticed that and just put the line back in and tightened it tight but not too tight to where i felt like it was just gunna start turning forever more less strip again and i have good pictures or a video if u need its not hard to get to i was planning on jbwelding it just putting a ton around it and just stopping the leak but im sure there is a simpler more straightforward way what do you think?