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73-87 Chevy _ GMC Trucks => Engine/Drivetrain => Topic started by: Lt.Del on October 06, 2008, 04:41:10 pm

Title: transmission fluid leak
Post by: Lt.Del on October 06, 2008, 04:41:10 pm

I got one for you master mechanics.
I walked around my 79 Big 10 today.  I haven't driven it for a few days and I noticed a puddle of tranny fluid coming from under the truck.

(http://www.delbridge.net/trfl1.jpg)

So i crawled up under it and at first thought it was the donut-type seal for the slip yoke.  But, it was dry all around that seal.
I looked closer at the drips--it is still dripping as I type this, and it seems to come from the yoke itself.. 

(http://www.delbridge.net/trfl.jpg)

Isn't there a hole that goes through the center of the yoke itself?  What could be wrong?  It drips directly from the u-joints....the yoke around the seal is dry so it couldn't be a bad seal there.   

Title: Re: transmission fluid leak
Post by: VileZambonie on October 06, 2008, 05:17:49 pm

there is a bulletin on those leaks. I used to just plug them but I'll see if I can dig it up for you

Title: Re: transmission fluid leak
Post by: Captkaos on October 06, 2008, 05:18:28 pm

First thought is this:
http://www.73-87.com/7387garage/drivetrain/yokeleak.htm

Title: Re: transmission fluid leak
Post by: Lt.Del on October 06, 2008, 10:54:18 pm

I don't remember that "cup" being there when I put my trans in the truck and slid the speedo gear on the tail shaft, maybe I just have alzheimer's, but I don't remember that being on my TH350c. 

Vile, if you plug the weep hole, what do you plug it with?

thanks for the help, as always.

Title: Re: transmission fluid leak
Post by: VileZambonie on October 07, 2008, 07:35:50 am

Jb weld works fine or if you don't have any clean it out and put in some good RTV

Title: Re: transmission fluid leak
Post by: ccz145a on October 07, 2008, 11:16:13 am

I packed some white lithium grease back in there.

Title: Re: transmission fluid leak
Post by: Lt.Del on October 07, 2008, 11:35:21 am

Thanks.  As soon as I get back from the Outer Banks of NC, I'll drop the drive shaft and tail cone of tranny and investigate the o ring.  If I can't see that, I'll just plug the weep hole up.

thanks for the input.
   

Title: Re: transmission fluid leak
Post by: Lt.Del on October 16, 2008, 05:24:09 pm

Well, I removed the driveshaft today.  Removed the tranny extension housing and speedo cable.  Saw the cup with the O ring.  Went to the salvage yard and removed a cup from an existing th350 and put it on my trans.  So far, no problems.


(http://www.delbridge.net/trann12.jpg)
(http://www.delbridge.net/trann13.jpg)