BIG Transmission fluid leak

[Channeled 91]

You're right..it is a vent. But...there is some silicone or plastic in that hole that gets brittle over time

I put a healthy amount of Liquid Weld over the hole. Its out on the workbench drying as I type.

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[df2x4]

This is on a 4L60E, right?

I Googled around a little because I remember reading about someone having similar issues years ago. It looks like there is an O-ring inside a sleeve on the tail shaft of the trans that can fail and cause fluid to leak through that hole in the yoke. Here's a link to a thread on PerformanceTrucks.net with some more explanation.

https://www.performancetrucks.net/f...n-22/4l60-2wd-driveshaft-yoke-leaking-553267/

 

[PlayingWithTBI]

It looks like there is an O-ring inside a sleeve on the tail shaft

Yes there is, I remember now when I put the reluctor gear on my 700R4 the O-ring and sleeve go on behind it.

 

[df2x4]

I found another thread on the subject with a picture of the sleeve and O-ring installed on the output shaft, I'm thinking this is probably where your issue lies @Channeled 91.

@PlayingWithTBI does this pic look like what you saw?

https://www.performancetrucks.net/f...id-out-slip-yolk-after-long-sit-482613/page2/

 

[Channeled 91]

Not the TSB being discussed, but may be related to OP's issue:

http://www.73-87.com/7387garage/drivetrain/yokeleak.htm

Before any other cabin fever tempers are triggered, anybody interested, please read the above linked article. It's short and sweet.

Richard

I did a bit of research and found the 4l60e and 700r4 uses the rubber shaft seal. I try to find it for the 4l60 and can not find it.

 

[alpinecrick]

I put a video showing the yoke does not hit the output shaft, and I was going to fill the small hole in the cat.

Your video doesn't seem to show what happens to the driveshaft when the rear suspension is almost bottomed out. With a lowered truck and stock length driveshaft, there is still a possibility of the driveshaft bottoming out on the trans output shaft.

 

[Channeled 91]

Your video doesn't seem to show what happens to the driveshaft when the rear suspension is almost bottomed out. With a lowered truck and stock length driveshaft, there is still a possibility of the driveshaft bottoming out on the trans output shaft.

The video shows the yoke and rive shaft when I drop the truck all the way to the ground from ride height.

this is ride height

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this is dropped.

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[alpinecrick]

Yes, I've watched the video several times. I'm trying to visualize the oring/seal in a 2wd tail shaft other members have pointed out and its relation to the yoke travel on the slip joint. With as much drop as you have even at ride height, I'm thinking a stock length driveshaft might be critically close to the limit of its slip. Driving over a set of RR tracks even at a slow 20mph for example.

 

[PlayingWithTBI]

@PlayingWithTBI does this pic look like what you saw?

Exactly! When I got the stage 2 trans from Transmission Depot, they didn't include the reluctor gear or the sleeve and O-ring (common with a lot of builders). I pulled the tail housing off (jacked up the rear higher than the front) and removed the OE O-ring and sleeve to get at the reluctor (pay attention to where the reluctor was in regards to the weep holes in the shaft), and installed them on the "new" tail shaft, then reinstalled the tail housing. No leaks or problems for about a year now, and my speedo works! Took about 1/2 hour after jacking the truck up.

 

[PlayingWithTBI]

I did a bit of research and found the 4l60e and 700r4 uses the rubber shaft seal. I try to find it for the 4l60 and can not find it.

The 700r4 and the 4L60 are the same transmission, GM renamed the 700R4 in 91 or 92 IIRC, to conform with their newer designations of "E" trans ie. 4L60E, 4L65E, on up.