Engine/Transmission (1994 - 1998) Leaky transmission fitting - HELP!

[WBusa]

Arrgh... one of the old metal quick-disconnect fittings on my transmission cooling lines (driver's side of trans, at rear of sump pan) has been slowly weeping since I bought The Beast six months ago. Since I installed my #6 TST plate last week the fitting has gone over to crying like a baby (coincidence? I think not). Anyway, so I know I need to replace the lines in the long run, but it being Christmastime and all (checkbook tapped out), for the moment I just want to replace that one fitting. I've read this thread: https://www.turbodieselregister.com/forums/showthread.php?t=114483&highlight=transmission+fitting

in which Joe G. describes replacing the fitting with a conventional compression fitting, but I have some questions:



1. What size do I want? I'm guessing the line is 1/2" and the hole in the transmission is 1/4 NPT?



2. Where the heck do I find a compression fitting like this? Ace Hardware? NAPA? A hydraulic hose shop? Eh?



3. Are brass fittings OK?



4. Dis/assembly: I'm guessing I disassemble the old fitting by spreading the wire and pulling it apart. Then I saw the end of the metal line off, back of the bulge in the metal line, and somehow or other I deburr the cut end. Then I slip the compression nut and sleeve on the line, screw the other side into the NPT hole in the transmission, then screw the two sides together. As I understand it, you tighten a compression fitting until you feel a sharp increase in torque, then maybe one turn further. Have I got this all right?



Obviously I'm new at this compression fitting business. Answers to the above four questions will be more than welcome.



Merry Christmas, y'all! Keep yer Cummins hummin in '05!

 

[tp0d]

I havent been under my truck lately to see what size the cooler lines are, but from what I can recall, they are a straight thru 3/8" flare nut. Have you tried tweaking down the nut? I know vibration causes these lines to hairline crack and that may not be the best thing to do, as it might just snap right off.



I`m close to you, i think. . in the pittsburgh area at least. and. . I`m a plumber. Lots of experience with flare and compression ends. Finding a fitting that is an oddball may be a problem during the holiday, as my specialty shops are closed. But my guess is, it shouldnt be too tough to match up. . I`ll drop ya a PM, mebe we can check somethin out sunday, if ya have a heated space to work. (me no like to work in cold heh)



-jerry

 

[Joe G.]

The lines are 1/2" OD steel. There are four quick disconnect and leak like crazy fittings. Two in the side of the transmission and two in the bottom of the cooler that is under the exhaut manifold. There is a ridge around the end of each line that has to be cut off. Deburr each of them. It's been some time since I did mine so I think the that NPT end of the transmission fitting compression fitting is 1/2 NPT and the ones under the cooler are the next size smaller. I got mine at NAPA. It's best to take one of each size with you to make sure that the NPT end is correct. I have a bad case of CRS so don't trust my memory on the NPT size. The forward line on the transmisson has the temp sensor in it. After the end is cut off the sensor will rub the edge of the transmission where the pan screws on. So use a short nipple to space it out a little. No funny business about installing compression fittings. Push the line into the fitting on the trans until it stops. Tighten the nut until it doesn't leak. It doesn't take much to compress the sleeve to make it take hold of the line.



If you have not already done so, you should protect the lines that cross under the front of the pan so they don't rub a hole in each other. I put a length of clear plastic tubing on one of them. Just slit the tubing so it will slip over the line without haveing do disconnect it. Tie wrap the tubing in place. Make the tubing lone enough so it just fits between the two clips that hold the lines together. Then the clips will still work.

 

[Howard Durand]

If I was going to use compression fittings again I would go to a hydraulic shop and get their steel compression fittings that are designed for use with steel tubing. I have a reason for not completely trusting the brass fittings.