rear main seal

[scouthead]

I didn't realize this until I saw it in print one day, and while my experience is maybe 10 among millions, any double lip seal surface I've ever dealt with was on the dust side of the seal, not the oil side. I still speedi-sleeve them, but that was before I realized I was never seeing two grooves.

The picture shown is a solid front axle truck, so IFS isn't a factor, nor is vertical clearance. IF there is nothing to keep the pan from dropping straight down, there is plenty of clearance to drop the pan on a squarebody 4WD. Looks to me like it's super easy:

Not to get into a pissing contest, but every Chev small block installed factory since 1987(?) until the end of production used a one piece rear main. I find it exceptionally hard to believe those are more problematic than the two piece seals in service. My only "personal" experience with them were my buddies 1990 Suburban and my other buddies 1995 3/4 ton both with 100K+ on the odometers. Neither leak a drop from the rear main. I've only had my L31 crate in for about five years, and it rarely gets driven, so I'd not use it as an example of long term success.

hope the pissing match/ hard to believe part wasnt about my posts- fully agree its way better than the 2 piece... I was only saying that on all the one piece seals I've had leak? they all had grooves worn into the seal surface, and simply replacing the seal itself was not a long term fix.


what was that first part about double seals and dusty groove stuff? I think i read that and understand it as you have found grooves, but usually only on the outer part of the seal?


-edit- and yes, the only pan Ive pulled off while engine still in the truck was a stock height 4x4 1989 Burb. -no wait, I also pulled the pan on my K5 when the I sheared the bolt on the main cap. But the K5 was lifted. That made it easier. In both cases, there was something wrong with the engine and I was not trying to seal a leak - I just needed to get eyes on all the fun parts.
From what I remember about My 1990 2WD suburban, and My buddy's 1997 Z71 with the IFS 4x4 -the crossmembers are bigger and wider than on the square body 4x4, closer to the oil pan, and there is a lot of other parts getting in the way of both Tools getting to the pan bolts, and also looked like there wouldn't be enough room to drop the pan and get it out.

 

[dyeager535]

Yep. The dual lipped seals serve two purposes. The outer lip is the dust seal, the inner is the oil seal. I assume based on them doing their job, the dust seal (from my experience) always cuts a groove in whatever surface they seal (pinion, t-case output shaft, etc). I'd bet if let go long enough, or not repaired, eventually the dust would make it to the inner seal and start cutting a groove too.

I imagine IFS/2WD would have significant clearance issues with dropping the pan. But the square body 4WD engine crossmember is much further forward.

 

[scouthead]

yeah every time I have had to deal with one leaking, there have been 2 grooves... and I once thought I could "get away with it" just replacing the front seal and not dealing with the grooves. nope. that didn't work for long. thought i could maybe play with the seating depth of the seal to miss the grooves and hit fresh material... meh. maybe.

that's what made me think that maybe the cast cranks were a lot softer - I've had other off-road vehicles that ended up getting rebuilt and/or refreshed after sitting, and the forged stuff never seems to have that problem. I've never had a forged crank in a Chevy (unless maybe my Lt1 in the 1995 Z28???)... so nothing for an apples to apples comparison.

 

[Wes Harden]

did the oil pan in the truck on @K5Devil 85, used the new 1 piece felpro great gasket. I am not keen on doing 2 piece rear main in the truck. It is a pita to get the upper part of the seal out, and difficult to clean and install the new neoprene lip seal. Rope seals no problem, all day every day. At the Buick agency, where I did heavy line, we called it and oil leak kit, rear main, oil pan gasket, and 2 valve cover gaskets on the 305/350 Buick blocks.

 

[Fastereddie]

I try to drive the seal in less or more so it rides in a different spot

 

[K5Devil]

did the oil pan in the truck on @K5Devil 85, used the new 1 piece felpro great gasket. I am not keen on doing 2 piece rear main in the truck. It is a pita to get the upper part of the seal out, and difficult to clean and install the new neoprene lip seal. Rope seals no problem, all day every day. At the Buick agency, where I did heavy line, we called it and oil leak kit, rear main, oil pan gasket, and 2 valve cover gaskets on the 305/350 Buick blocks.

That new 1 piece gasket sure is slick. No leaks either.