TH350C/700R4 yoke weep hole: To plug or not the to plug?

[CheemsK1500]

My TH350C on my '85 C10 like spit a large amount of fluid out of the yoke weep hole when it sits for about 2 or 3 days. It is my understanding that an O ring needs to be replaced on the little cup on the output shaft. I will go ahead and do this, but in the unfortunate case this does not stop the leak; is it safe to resort to plugging the weep hole? I just replaced nearly all the other seals in this transmission, I really don't want to blow them out or worse yet put even more wear and tear on this old transmission. Thanks.

 

[PrairieDrifter]

My TH350C on my '85 C10 like spit a large amount of fluid out of the yoke weep hole when it sits for about 2 or 3 days. It is my understanding that an O ring needs to be replaced on the little cup on the output shaft. I will go ahead and do this, but in the unfortunate case this does not stop the leak; is it safe to resort to plugging the weep hole? I just replaced nearly all the other seals in this transmission, I really don't want to blow them out or worse yet put even more wear and tear on this old transmission. Thanks.

As long as the vent on top of the trans case is clear you should be fine.

 

[CheemsK1500]

Update: I’ve replaced the O ring inside of the cup. I will watch it the next the few days. If it still leaks, I’m going to plug the yoke.

 

[CheemsK1500]

New update: It has been nearly a week and the transmission still seems to be holding its fluid after the O ring change. I guess I’ll leave the weep hole for now.

 

[CheemsK1500]

New update: After about a week and a half, the yoke weep hole leak has returned, though the puddle is much smaller. I don’t know if I should just plug it or live with it. The amount of fluid lost seems pretty marginal but it’s very annoying regardless.

 

[PrairieDrifter]

New update: After about a week and a half, the yoke weep hole leak has returned, though the puddle is much smaller. I don’t know if I should just plug it or live with it. The amount of fluid lost seems pretty marginal but it’s very annoying regardless.

I would plug it and be done with it. But I have an absolute hate for leaks lol

 

[CheemsK1500]

I would plug it and be done with it. But I have an absolute hate for leaks lol

As much as I hate resorting to “unauthorized fixes” I might just make an exception for this. I just wish I knew why it is set up this way in the first place. It’s weird how only the full size trucks have this and not the various cars of similar vintage. Does towing generate more pressure in that area or something?

 

[PrairieDrifter]

As much as I hate resorting to “unauthorized fixes” I might just make an exception for this. I just wish I knew why it is set up this way in the first place. It’s weird how only the full size trucks have this and not the various cars of similar vintage. Does towing generate more pressure in that area or something?

There has been talk about it in other threads. Maybe search for those. To add to the confusion not all of the yokes had that weep hole or seal. I'm not sure if it was a manufacturing thing or what, but I don't see why they would drill holes in em for no reason, but not all of them? When I built my sub, it still had original plastic filled u joints and no weep hole.

 

[CheemsK1500]

Interesting. Another thing I’ve learned is that there are Mopar automatic transmissions that have the same kind of weep hole such as the 48rfe on third gen Dodge Ram 2500/3500 pickups. Clearly GM is not the only ones to decide to use this odd vent mechanism. Granted, the inconsistent usage of this setup on factory vehicles is baffling, and really makes me wonder how essential it actually is.

 

[PrairieDrifter]

Interesting. Another thing I’ve learned is that there are Mopar automatic transmissions that have the same kind of weep hole such as the 48rfe on third gen Dodge Ram 2500/3500 pickups. Clearly GM is not the only ones to decide to use this odd vent mechanism. Granted, the inconsistent usage of this setup on factory vehicles is baffling, and really makes me wonder how essential it actually is.

It may be a drain so if fluid does get in the yoke it doesn't essentially "hyrdolock" and blow something apart. I haven't had a problem with my replacement that doesn't have a weep hole in 30,000 miles.