problem with "rebuilt" TH350 tranny

[sbx22]

'74 1/2 ton 2wd long bed with TH350 tranny. I've replaced the whole drivetrain due to previous issues and problems. Done with swapping motor as well as a rebuilt tranny. I start the truck up, do the proper break in procedures for the motor, drive it around the block, come back, let it sit. Moments later, I see a pool of red fluid under my truck (tranny fluid). I trace it, and it's coming from the driver's side border of the tranny pan. Could it be that the shop that rebuilt the tranny "incorrectly" installed the gasket? Sheesh, I thought I'd be driving it by now. Am I missing something here? I slightly tightened up the bolts more, but still leaking. I've bought a felpro gasket so that I can take it apart this weekend. Any tips or suggestions appreciated.

[snibook7537]

I don't know about you but I'd take it back and complain, kind of would make me leery about trusting that transmission at all.

[firefighter]

I can't think of anything that would make it leak there besides a faulty gasket or pressure being built up inside the transmission body, and that should not be.

[69byrd]

I don't know about you but I'd take it back and complain, kind of would make me leery about trusting that transmission at all.

I agree I would make the builder fix it.

[sbx22]

I may just have to call the guy up. I'm going to attempt to change the gasket or re-torque the bolts to specs and see how it goes this weekend. If that doesn't work, then he's going to get a call. I'd hate to take the tranny back out.

[VileZambonie]

Are you sure it's not just running across there? It's not wet anywhere else?

[sbx22]

But this isn't coming from the gasket. I've had the gasket switched already, and now, I'm 99% this is where it is coming from. I don't know what this part of the tranny is called, the part where it shifts. See red arrow below. I believe this is the culprit. I've never taken apart a tranny before. Can anyone tell me if this part has a rubber gasket that may be bad or something?

[87454westernhauler]

would that have an o-ring gasket??

[bd]

Perhaps the builder never installed the seal(?).

The "shift shaft seal" is a press-fit rubber lip seal moulded into a steel collar.  It presses into the case over the shaft from outside the trans.  You can replace the seal w/o removing the pan if you use a special tool like the one pictured from Napa (P/N:  BK 7769250) for under $10.  It should be generally available from most parts stores under various brand names.  All you have to do is remove the external lever then screw the black puller into the old seal, tighten the center screw to remove the old seal, then drive the new seal in with the silver tool.  It's an easy fix as long as the shaft & case aren't too worn.

The question is:  Why not drive the vehicle to the trans builder and have him change the seal w/o pulling the trans back out?

[sbx22]

I'm not even thinking about taking the tranny out, that would suck if I had to. Anyway, if it's an easy fix, i'd rather do it myself on the weekend. From the looks of it, I won't have to take the tranny out, just mess with the shifting part while under the truck. Plus, I've been working so much that I won't have time to drive there and back (picked this tranny 2 hours away from me). Thanks for all the helpful information, leads me to a good direction.

[sbx22]

http://www.napaonline.com/Catalog/CatalogItemDetail.aspx?A=NOS4912_0075388444&An=599001+101974+50014+2014024+28239&Ar=AND%28P_RecType%3aA%29

Ha! found it.

[VileZambonie]

You can change the shift shaft seal in the truck. I have the tool pictured which is nice but a pick tool and pocket screwdriver and a socket can do the trick as well.

[sbx22]

I got it fixed this weekend yah! no leaking so far... knock on wood.

[bake74]

     Glad to hear you got it fixed and hopefully it wasn't too hard.