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Hi Guys, I’m really trying to keep my driveline on my 48 gmc all original but after a ton of money and dealing with 2 shops my trans is leaking so badly that if I want to drive it I have to almost fully refill it. It’s so aggravating I won’t drive it and every time I look at it I’m tempted to just pull it all and replace it with a modern engine and trans. So before I do I thought I would ask if any one knows of a reputable mechanic shop capable of stopping the transmission leak. (It’s leaking from the rear) I’m NE Ohio And would like to stay within 500 mile if possible, but would go further for positive results. Thanks

Jim, first thing. Can you share a bit more about your '48 GMC, What is the particular model, 3 speed or 4 speed.

RonR

Added in edit; ok, a search showed you've been working on the problem already. There are some very knowledgeable folks here, I'd continue to seek out advise and not give up to quick. One thing about today's shops is they don't have the generational knowledge to work on our trucks with any certainty. You need to find one with old geezers, lots of gray hair, possibly a pair of overalls or two and it doesn't hurt if there's a good bit of old oil soaked concrete in a lot of the shop.


Good Luck
RonR

Hi Ron,
It’s a 48 gmc fc-100 and it’s got a 228 with a 3 on the tree. After 2 shops failed to even remotely slow down the leak, actually it got worse I did take a stab at it. Unfortunately I was not able to do any better. I’m not giving up but this has been a ongoing issue that has gotten progressively worse with no end in site, I really just want to drive my truck and enjoy it. So hopefully there’s someone out there with the knowledge to fix it.

throw some pictures up and lets take a look. You didnt mention what they have done already to the trans?

Where is the leak?

Is the transmission leaking (from where?)?

Is the leak at the rear u-joint cover/"bell"?

Make sure the proper wt gear oil is in the transmission. The easy button would be someone put automatic transmission fluid in it. Now if they did, and everything was in perfect condition, likely no issues other than a lot of gear whine. But everything isn't perfect so a small manageable leak would become a problem.

Guys, thanks you for the responses, first I will post photos later and the proper gear oil is being used. The leak is at the rear of the trans where it connects to the enclosed driveshaft. I believe the fluid is also now leaking down the tube because the rear is now leaking and it wasn’t before. The first shop put in a new clutch so while it was out they Supposedly took the whole drive line out and put it back with new shims, gaskets. Problem is it leaked worse so I went to a second shop where they tried to fix the ball valve in the rear of the trans to stop the leak but it’s actually worse. Pics to come, but again still looking for a shop as I feel this is above my skill level. Thanks

It should be an easy thing to follow Jerry's (Hotrod Lincoln) advice from your other thread? "Back the nut all the way off, and see if the seal between the nut and the pivot ball is damaged or missing. Those are still available, and I believe some of them have a diagonal cut that allows the gasket to be installed without dismantling the entire torque tube/universal joint assembly.
Jerry" The nut he references is on the end of the transmission tailshaft.

If it were my truck, I'd do my best to find the split seal Jerry referenced. Someone may jump in with a source. With said seal in hand I'd place a container under the transmission tailshaft, back the nut referenced above off and replace the seal just because it might work. I've never attempted this but how hard can it be. Famous last words at my place.

The photo in the other thread shows exactly where the leak is coming from. It's an easy fix. Even if the OEM packing is not available, there are plenty of sources for square rubber O ring material that will solve the problem. I can't imagine anyone with the unmitigated gall to call himself a "mechanic" being unable to do something so simple!
Jerry