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Just thought I would share my little  discovery. Started to notice some seepage out of the ZF not a big deal . Then my truck blew up and the Pantera become my main mode of transportation .That seepage quickly become a issue , not saying it was leaving a puddle wherever it was parked but left a spot almost always, even quick stops . I really didn't know what or  why all of a sudden ?,little over  48k+ on the car that I inherited from my father and he bought it with 14k in 1975 / 79? . So after checking all nuts & bolts , and staring  at it , a lot , Light Bulb , took the old breather tube off got a zip tie stuck it down the little metal fitting , notice more resistance than it should , imho, spun it around and in and out new  hose drove around  and no more leakage  . Guessing over time sporadic use, heat, sitting , driven a little then sitting for a few more years,,,,,,,, Anyway  if your zf  has had a  similar symptoms without a  lot of miles , worth a try .

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I haven't moved to synthetic (yet?) but the car has had the ZF fluid changed yearly for the past 4/ 5 years , I had always been apprehensive about driving it very far , mostly because I had become accustomed to how  the car was ? idk when my father had it there  was  the might get hot thing so mostly driven at night and not very far even that was no guarantee . That was Before the  world wide web, and access to,,,, well,, the world wide web and its information , my father loved that car unfortunately he didn't get to experience the doesn't get hot any more version . We had a ranch and family business in northern California and I was the mechanic ,of a wide range of equipment , machines and vehicles , but that car was not included in that list . Until his frustration of him having trouble getting it tuned like he wanted along with my sarcastic comments re my car being able to blow the doors off his , he  gave in . I tuned that car he took it for a  drive came back all i could see was teeth after that Nobody else touched that car mechanically again . I apologize for going on a little walk down memory lane , doing so gives me a smile mmmmm almost like his after I tuned his car . So  no  synthetic but regular fluid changes , And I am almost glad my truck blew, I now have complete confidence to drive that car anywhere .

Where is it leaking from? If it is from under the rear cover acorn nuts you can put o-rings under those.

That's usually the spot the ZF will leak from when you put in synthetic. I have synthetic in there and it dripped initially. Hall told me to do the o-rings and it worked. That's how long ago I did it. Gary's been gone for almost 20 years now.


As you may know the ZF is installed upside down in our cars so a sealing system for the nuts on the "bottom" wasn't required. I tried using sealing crush washers awhile back with limited success. A few years ago someone purchased a large lot of acorn nuts with o-rings which worked quite well. I looked into this. Only a few companies advertise these. The one I did find (Zago) requires a minimum order of something like a 1000 and at a couple bucks apiece that 's not going to happen. I'm going to try o-rings under thin washers with acorn nuts next.

After a lot of miles, another source of leaks is the halfshaft seals in the side covers. They're a bit of a pain to do since they go in from the inside, so the iron cover must come out first. And if you DIY, don't cheap out- use genuine ZF side cover gaskets. Far-east 'equivalent' gaskets may be a different thickness, which will change the ring & pinion pre-load setting.

The reassembled ZF may not leak, but preload changes can make noise when under power, or more rarely when backing off the accelerator.Then you get to re-shim the side covers to reestablish the proper pre-load, which is kind of a pain. This also sometimes happens when replacing the ring & pinion gears for a different ratio.

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