The oil cooler on my 87 300TDT began leaking from the upper oil hose the other day. Upon removal I discovered that the threads on both the oil line nut and the fitting on the cooler were totally stripped. Luckily I had a second set of oil lines, as the replacement lines aren't cheap. The question is, can a new threaded fitting be sweated on at the radiator shop, or am I looking at a new one? I will ship it anywhere if someone has a good shop to recommend.
Thanks,
Steve

The problem with those coolers fittings is that they are aluminum and the hose fitting is steel. We have cut the threaded section from one and TIG welded it to another for a good repair. The only way to do this though is to have a bad cooler with at least one good set of threads.

I would be glad to do it for you, but coming up with the threads is the problem. I'll check and see if we have any damaged coolers in our metal pile if your interested.

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Steve Brotherton
Continental Imports
Gainesville FL
Bosch Master, ASE Master, L1
33 years MB technician

Steve,
I'm interested in your offer. If you find a used cooler in your shop, let me know and I'll send you mine. There is a chance that a local shop has a broken one--I'll check it out Monday and get back to you.
Thanks
Steve Hutson

It IS possible to change leaking oil cooler lines without stripping the aluminum threads but you must use extreme care when removing the line fitting. If you crack it loose first and then, as you back it off, go a little ways back then a little ways forward at each turn of the wrench, you should be ok. I've done this several times and have always had good luck.

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Regards,
Aaron

I have cut the steel fitting off a number with a carbide wheel. Four straight cuts on the fitting. Some will have so much aluminum gone that the new fitting won't hold.

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Steve Brotherton
Continental Imports
Gainesville FL
Bosch Master, ASE Master, L1
33 years MB technician

Aaron,
Thanks for the reply. The leaking fitting was the one that was stripped, and it looked like someone had applied some kind of sealer on the threads to get it to hold. Of course, the line that was leaking was the one that was hardest to get to, once again proving Murphy's law! I'm realizing now that the trick is on installation to get it just tight enough to not leak, but not too tight so as to strip the threads. One of the axioms of plumbing is never to use dissimilar metals in contact with eachother,so I wonder why MB would have designed this set up, when a simpler o-ring set up would have worked. Do you recommend some anti-sieze
paste on the threads for assembly?
My strategy for this one shall be: 1) find good used cooler
2) find bad used cooler and weld fitting, 3) bite the bullet
buying a new one.
Sincerely,
Steve