Cracked Transmission Housing Around Cooler Fitting

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whaleinafishbowl

whaleinafishbowl

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Mar 11, 2016
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Denver, CO
Well 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.
I was basically devastated when I saw the crack forming, thinking I totaled this 20 year old jeep doing preventative maintenance, but 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?

Sorry for the wall of text, just looking for any input to make this repair as painless as possible. I already used some marine JB Weld around the fitting, and its holding and not leaking, but I'm obviously not driving the jeep until I get this "repair" fitting installed.
 
Originally Posted By: Donald
Make sure you use a "bottoming" tap, its different than a normal tap.


Thanks for the reply, I ordered the whole kit and it comes with the specific tap. Is it really obvious when it bottoms out?
 
Originally Posted By: dlundblad
I had no idea this problem existed. My Jeep as the same transmission.


One thing I've learned from this is to never use teflon tape on aluminum, it is actually designed as a thread lubricant and not a sealant that might be why I didn't feel any more resistance. I will be purchasing some pipe dope/sealant for the repair fitting install.
 
Originally Posted By: whaleinafishbowl
Originally Posted By: dlundblad
I had no idea this problem existed. My Jeep as the same transmission.


One thing I've learned from this is to never use teflon tape on aluminum, it is actually designed as a thread lubricant and not a sealant that might be why I didn't feel any more resistance. I will be purchasing some pipe dope/sealant for the repair fitting install.


Yup. Same argument as "don't put anti-seize on spark plugs because lubrication will reduce the torque reading for the same amount of force on the threads and you'll strip the cylinder head." (I use anti-seize and scale down the torque, personally).

Hopefully the repair will work, it looks like it depends on the crack NOT extending all the way through the case but just being in the raised "boss" area.
 
Originally Posted By: 440Magnum


Yup. Same argument as "don't put anti-seize on spark plugs because lubrication will reduce the torque reading for the same amount of force on the threads and you'll strip the cylinder head." (I use anti-seize and scale down the torque, personally).

Hopefully the repair will work, it looks like it depends on the crack NOT extending all the way through the case but just being in the raised "boss" area.


I hope so too. It seemed to be leaking just on the "boss" and I'm hoping the JB weld will help block any seepage if it gets past, but I'm not super confident in that.
 
Originally Posted By: whaleinafishbowl
Originally Posted By: 440Magnum


Yup. Same argument as "don't put anti-seize on spark plugs because lubrication will reduce the torque reading for the same amount of force on the threads and you'll strip the cylinder head." (I use anti-seize and scale down the torque, personally).

Hopefully the repair will work, it looks like it depends on the crack NOT extending all the way through the case but just being in the raised "boss" area.


I hope so too. It seemed to be leaking just on the "boss" and I'm hoping the JB weld will help block any seepage if it gets past, but I'm not super confident in that.


If it fails you could loose the transmission. I would make sure it's fixed with something other than JBWeld.
 
Where in Illinois do you live? Pull the trans and bring it to me, if the JB Weld doesn't cause too big of a problem, and I'll weld it.
 
Originally Posted By: Donald
Originally Posted By: whaleinafishbowl
Originally Posted By: 440Magnum


Yup. Same argument as "don't put anti-seize on spark plugs because lubrication will reduce the torque reading for the same amount of force on the threads and you'll strip the cylinder head." (I use anti-seize and scale down the torque, personally).

Hopefully the repair will work, it looks like it depends on the crack NOT extending all the way through the case but just being in the raised "boss" area.

I hope so too. It seemed to be leaking just on the "boss" and I'm hoping the JB weld will help block any seepage if it gets past, but I'm not super confident in that.


If it fails you could loose the transmission. I would make sure it's fixed with something other than JBWeld.


The JB Weld is a second line of defense, I will be installing the Sonnax repair fitting #22000-01 http://www.sonnax.com/parts/1815-cooler-line-adapter#tabs1-instructions
 
Originally Posted By: tig1
Where in Illinois do you live? Pull the trans and bring it to me, if the JB Weld doesn't cause too big of a problem, and I'll weld it.


I am in the City of Chicago. Thank you so much for your offer, but I am try to avoid dropping the transmission. I will keep you in mind if the repair fitting does not work as advertised.
 
Originally Posted By: Donald

If it fails you could loose the transmission. I would make sure it's fixed with something other than JBWeld.


As he said, the JB is a backup. But even still, its not going to be a geyser of a leak if the crack re-opens. A few drops a minute, more likely, and a small puddle where you park it to let you know its leaking.

The whole root problem is putting NPT fittings into a non-ductile material. N(ational) P(ipe) T(hread) was developed for ductile cast iron...it puts a lot of circumferential stress on the female thread side, which helps it seal tightly, but doesn't play nice with hard cast iron, aluminum, and other more brittle metals.
 
Originally Posted By: 440Magnum
Originally Posted By: Donald

If it fails you could loose the transmission. I would make sure it's fixed with something other than JBWeld.


As he said, the JB is a backup. But even still, its not going to be a geyser of a leak if the crack re-opens. A few drops a minute, more likely, and a small puddle where you park it to let you know its leaking.

The whole root problem is putting NPT fittings into a non-ductile material. N(ational) P(ipe) T(hread) was developed for ductile cast iron...it puts a lot of circumferential stress on the female thread side, which helps it seal tightly, but doesn't play nice with hard cast iron, aluminum, and other more brittle metals.



Thanks for the input, That really interesting about the NPT threads.
 
Do any experienced Machinists have any pointers for tapping into an Aluminum transmission housing? I have a can of CRC cutting oil, any other suggestions?
 
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