Periodic leak from tail shaft - 4L60e, 93 Suburban 5.7l

Hi, I have a 93 Suburban 5.7l, 4L60E

I came back after letting the truck sit for 3 weeks and there was large puddle under the tail shaft. I could see drips on the universal joint.
I normally drive the truck every 1 or 2 weeks to hardware store, etc. and I've never seen drips from tail shaft seal. I occasionally add some tranny fluid so it could be leaking when driving but I don't notice. I put cardboard under and saw it was continuing to drip slowly.
I started truck, moved it forward 5 inches and no more dripping even after a few days.

Two questions
1) Is replacing tail shaft seal as easy as removing drive shaft, prying out the seal and tapping in another?
2) Curious as to why the apparent intermittent dripping. Is this just the fact I have a bad real seal and I let it sit so long this time that fluid drained out of torque converter and raised the level to where it could get to rear seal? or could there be some weird rotational position thing where it leaks at some points and not others? If so - that would be concerning, I'd think as something would likely be workout inside...?

Thanks!
Ed

Sabinoerc said:

Hi, I have a 93 Suburban 5.7l, 4L60E

I came back after letting the truck sit for 3 weeks and there was large puddle under the tail shaft. I could see drips on the universal joint.
I normally drive the truck every 1 or 2 weeks to hardware store, etc. and I've never seen drips from tail shaft seal. I occasionally add some tranny fluid so it could be leaking when driving but I don't notice. I put cardboard under and saw it was continuing to drip slowly.
I started truck, moved it forward 5 inches and no more dripping even after a few days.

Two questions
1) Is replacing tail shaft seal as easy as removing drive shaft, prying out the seal and tapping in another?

Click to expand...

Pretty much.

Sabinoerc said:

2) Curious as to why the apparent intermittent dripping. Is this just the fact I have a bad real seal and I let it sit so long this time that fluid drained out of torque converter and raised the level to where it could get to rear seal? or could there be some weird rotational position thing where it leaks at some points and not others? If so - that would be concerning, I'd think as something would likely be workout inside...?

Thanks!
Ed

Click to expand...

What's happening is the torque converter drains down when you let it sit for awhile and raises the fluid level up high enough for it to run out the rear. Most of your fluid loss is happening after you shut the motor off.

Sabinoerc said:

Hi, I have a 93 Suburban 5.7l, 4L60E

I came back after letting the truck sit for 3 weeks and there was large puddle under the tail shaft. I could see drips on the universal joint.
I normally drive the truck every 1 or 2 weeks to hardware store, etc. and I've never seen drips from tail shaft seal. I occasionally add some tranny fluid so it could be leaking when driving but I don't notice. I put cardboard under and saw it was continuing to drip slowly.
I started truck, moved it forward 5 inches and no more dripping even after a few days.

Two questions
1) Is replacing tail shaft seal as easy as removing drive shaft, prying out the seal and tapping in another?
2) Curious as to why the apparent intermittent dripping. Is this just the fact I have a bad real seal and I let it sit so long this time that fluid drained out of torque converter and raised the level to where it could get to rear seal? or could there be some weird rotational position thing where it leaks at some points and not others? If so - that would be concerning, I'd think as something would likely be workout inside...?

Thanks!
Ed

Click to expand...

Is it leaking at the sealing surface where the slip yoke makes contact with the seal at the 6 o'clock position or is it leaking from the underside of the seal between it and the extension housing surface? Most leaks are of the former variety but I've seen some leak between the outer diameter of the seal body where it's pressed/hammered into the inner diameter of the extension housing's seal bore. If the latter, you'll want to remove the seal, inspect the seal bore for physical defects...If minor wear is noted, put some RTV on that part of the seal to prevent future leaks. If the bore is markedly worn out, simply replace the extension housing with a good used one.

Otherwise, yank the driveshaft, inspect the slip yoke for a groove cut into it by the seal....If noted, replace the slip yoke...Otherwise take a screw driver, hammer and tap the seal out between the seal's flange and rear of the extension housing. Then get in behind it and smack it out...Have a catch pan for fluid as some will drip...

Install the new seal with a large bushing driver or equivalent tool; put RTV on the outer seal surface that goes into the seal bore on the ext housing, if necessary.

when you remove the seal dont scratch the inner bore of the housing. when you put in the new seal put some rtv on it to fill any scratches. if the yoke is grooved you will need another one. if the yoke is ok make sure the plug in the center is not whats leaking, all of my gm trannys except my very first 400 leak after setting awhile, i think its from ****** rebuilds. the 400 has never been rebuilt, its in my 63 j200 jeep/sbc

inspect the inside of the yoke closely, the seal leaking probably wont put any oil up in the center infront of the ujoint but if the plug ha

sorry i having trouble getting used to a laptop, if the center infront of the ujoint is wet the plug is probably leaking, sometimes the plug gets pushed out of position from the hyd pressure created in the splines of the yoke if it gets pushed all the way on the shaft by a mechanic installing the driveshaft.

Is this 2wd or 4wd?

Supercharged111 said:

Is this 2wd or 4wd?

Click to expand...

2WD

NickTransmissions said:

Is it leaking at the sealing surface where the slip yoke makes contact with the seal at the 6 o'clock position

Click to expand...

Looks like the bottom of the seal and running back to the u-joint - but I didn't crawl under to get a really careful look at it. It was 105F that day and parked in the gravel...

Thanks for the replies! appreciate the knowledge and suggestions. I plan to replace the seal.