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

[NickTransmissions]

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...

Yea, if you're in Phoenix it's one of the few major cities hotter than here (Las Vegas)..Think Tucson is about the same temps as Vegas...Pound the seal out w/a screwdriver and/or seal removal tool then look carefully at the ext housing's seal bore...My guess is that it's worn, out-of-round, etc and just needs RTV on the seal and bore to prevent leaks. You can do this regardless of whether it's actually coming from the bottom or just appears to be (you do have to get underneath to verify, hard to do otherwise. As mentioned, look at the slip yoke for grooves cut into it...Replace the yoke if so...

 

[Sabinoerc]

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

I'm not surprised it's leaking - I've had this suburban since new and now 199k on it and transmission's never been out. I've been into pan and valve body but that's it.

 

[Sabinoerc]

Yea, if you're in Phoenix it's one of the few major cities hotter than here (Las Vegas)..Think Tucson is about the same temps as Vegas...Pound the seal out w/a screwdriver and/or seal removal tool then look carefully at the ext housing's seal bore...My guess is that it's worn, out-of-round, etc and just needs RTV on the seal and bore to prevent leaks. You can do this regardless of whether it's actually coming from the bottom or just appears to be (you do have to get underneath to verify, hard to do otherwise. As mentioned, look at the slip yoke for grooves cut into it...Replace the yoke if so...

Thanks - yeah, I'm in Tucson which is "cooler" than Phoenix at least! But as much as I drive this, just weekend errands, etc. - I'm hoping I can keep it filled/moving without too much leaking until it cools down a bit - we'll see.

 

[Supercharged111]

2WD

I'd replace the internal seal while you're at it. You mentioned the ujoint being wet, that'll stem from the internal seal either failing or not existing. This isn't a factor for 4wd. You'll need to remove the tail housing to gain access to it. The long metal collar in this pic has the seal in it.

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[Drunkcanuk]

One thing that hasn't been mentioned yet is to check for pitting or rust buildup on your shaft where it slides into the tranny ( that sounds dirty,lol) if it has crap built upon it it can/will tear up the seal.
Just take some emery cloth and shine that thing up.
And ya, easy to replace, easier if you have the right kinda driver kit or a big enough socket.

 

[Erik the Awful]

I'd also replace the VSS o-ring. My son's truck was leaking from the VSS. We fixed that and now it's leaking from the rear seal.

 

[chasw44]

I just remembered about chevys leaking at the valve covers from a stopped up pcv valve and the tranny has a vent on the top make sure it has not gotten one of those little bees in it that plug them up. Every hole in anything around here gets bugs building nest inside them. You never leave a air hose outside or it will get plugged up.