Weeping gearbox


True Classic
My gearbox always leaves a nice puddle under the car and with the motor/trans out of the car I finally go to looking at where the Redline is coming out.


The arrow points to the seam it's dripping out of, the lower pic just gives a better idea of orientation. It is a lower portion of this gasketed seem.

I'm not motivated enough to pull the gearbox apart to reseal the seam so is there a sealant I can apply externally that will work? Yes, that sounds tacky but you all know you would do it too. Smart asses who say go back to GL-1 will be dealt with swiftly and hurtfully.


True Classic
Is the blue material already in the seam (to the right in the second pic) a gasket or a sealant material (liquid gasket of some sort)? If it is sealant then I'm surprised it is leaking. Possibly the cases got warped or damaged along there? I guess it does not matter, just curious.

While the purists may say it is better to tear it down and redo everything with 100% new parts, I'm with you...I would not if it is working fine. You could buy a LOT of trans lube for the price of one replacement internal part.

I am picturing some sort of rig connected to the fill port with a couple of extra quarts of lube draining slowing into the trans, as it drips out the bottom. Like a big one of these:

I suppose if you can temporarily stop it from leaking (e.g. turn the unit upside down), and thoroughly clean all traces of Redline and other materials off the area (maybe use something like acetone), then a bead of sealant could be added along the seam. I really doubt it will stop the leak; most likely it will follow another path along the seam until it can drip again. But it might slow it down, for awhile anyway (they always seem to fail again eventually). Won't hurt to try, other than more to clean off if you ever do have to go inside it.
I like synthetic lubes (I'm a fan of Redline), but they do leak more easily.


Daily Driver
I've fixed an oil leak and a water leak with a ight smear of red RTV. Both were at seams on Fiats after putting cylinder heads on. All good practices known to me were used during assembly, but WTH, here's a leak. Blasted with brake clean and puttied the seam. Let set up overnight.

Sure, I planned it as a quick, temporary fix but both cars still good today, both done more than 5 years ago. I wouldn't hesitate to do the same deed on a transmission.

Rod Midkiff

True Classic
now that the gearbox is out... opening it enough to re-set that is at best an hour.. you already have the hard part done. and nothing critical has to be opened to reset that part.


True Classic
Well, it seems that was not the source of the leak, although the responses above were interesting. I think now it is coming out one of the threaded holes that is used to attach the motor mount.

On the lower right threaded aperture I see fresh lubricant (notice the paper towel is wet just below it). You may recall that on one of the (many) installs of the drivetrain I complained that the shifter was stuck, would not move and someone suggested that I may have used a bolt that was too long. I had, and a shorter bolt freed up the gearbox. Was this originally a blind hole and forcing the long bolt to tighten may have cracked the trans body and created the leak source? I'll verify tomorrow with a bolt with sealer on it installed in the hole. If this is the source of the leak, would you use a stud with Teflon tape or just a bolt with Teflon tape?

Rod Midkiff

True Classic
I would put money that bolt is at least part of the leak. maybe put a bolt in with Teflon tape and see if it slows/stop's the leak. That would be sooooo cool if that is all it takes!!


Eric Hamilton
Was this originally a blind hole
and forcing the long bolt to tighten may have cracked the trans body and created the leak source?
more likely it just punched out the very thin bottom of the blind hole... at least that was the problem when I didthis happened to me.

Lots of sealant on the threads of the new shorter bolt fixed it.


True Classic
I have never had any luck with Red Line MTL, it always leaked, I changed shaft seals and gaskets. Once the leak has started going back to GL-1 without a tear down accomplishes nothing GL-1 will leak as well. I have a sheet of card board under the car at all times. I never saw any Improvement with Red Line either when shifting. You may be able to goop it up externally, but I suspect it will not last long.

Best of luck with this.


Grimsby Ontario Canada.


True Classic
I recall that prior discussion when your trans would not shift, due to the longer bolt interfering with the internal linkage. And it was stated then by someone (don't recall who) that the longer bolt does indeed go through the case, piercing the blind hole, causing the shifter interference....just like Eric said earlier. So that would explain the leak.

I suggest the same approach I described earlier; flip the trans upside down to stop the fluid from passing the hole. Clean it thoroughly. Then use a sealant. But this time on the bolt (or a stud may be easier if you are doing this with the trans out and flipped over). Let the sealant dry before reinstalling the trans. Should be good for as long as it takes for the next issue to occur, whatever that will be. That's a big part of the fun; it's a mystery guessing what's going to go wring next. :D


True Classic
Seeing as how the box is out I would pull the cover and put on a new gasket or gaskets.
I have made several tranny gaskets.
You can get the material at any automotive parts store.
Make sure you use the same thickness paper as the original.
On old stuff like this I use permatex aviation sealer in conjunction with the paper gasket.
If you don't think you can pull the trans apart and get it back together then the possibly next best thing would to just remove the bolts and pry the case apart until you have at least a quarter inch space all around clean the lube away and and run a bead of form a gasket all the way round let set then torque the case back down.
A superficial smear over the out side isn't going to do the job.

If you think it is the blind bolt hole that is by the shift rod then pack the hole with a plug of fairly thick gasket material and a shot of form a gasket on top let set then lather up the threads of a stud with sealer and run it in until you can feel it bind the shift rod then back off until the rod moves freely.
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True Classic
Sealing a stud or bolt in an oil access hole should not be a big deal. On the TC motors there are three exhaust manifold mounting studs that go in threaded holes that pass through into the cam box which is loaded with hot motor oil. Usually the rear stud starts leaking (onto the exhaust manifold!) and the normal fix is to pull the stud, put Teflon tape on it and reinstall...problem solved. Should get the same results here.

gene cooley

Back when I had my 128SL there were occasional bad days where the 2nd and 3rd gear synchros were weeping, (or maybe even brought to tears) but the oil stayed inside the trans until I had to open it and scrape out the pieces.


Old enough to know better
With my apologies to George Harrison:

I look at my car, and I know that it's leaking
While my gearbox gently weeps.
I look at the floor and I see where it's seeping
Still my gearbox gently weeps...
That is so bad, yet so very good...


True Classic
Speaking of workbenches....oh, wait, getting off topic again. O.K. back to shiny objects then. What were we talking about? That reminds me, the other day I was talking to someone and ....ooops.