Rear Main Seal Replacement

[sdelaney]

Well, on my 1983 C20 6.2 I seem to have developed a substantial rear main seal leak, oil pan gasket leak, or both.

It's a two piece rear main and seems like I should be able to do it without moving the transmission or jacking up the engine.

Just remove the inspection cover and maybe the starter, drop the oil pan, remove the oil pump and rear main cap, and so forth.

Sound about right? Any pitfalls I should be aware of?

I tried to search the topic in this forum but it returned a few thousand results.

Any advice would be appreciated.

Thanks

[Robyn]

Just about right.

Same basic thing you would do on an early RAT OR MOUSE MOTOR...

If YOU ARE LUCKY and the engine has a hard backed neoprene seal it's pretty easy to shove the old one out and the new one in.

If you find the rope type seal it can be a bit more work...


Good luck

JUST AN FYI

These engines use a high temp silicone goop on the pan rails, so do not be shocked if you do not find a gasket...

Gaskets were not used on these engine on the pan and rocker covers... only the goop.

[sdelaney]

Hey thanks!

So is it a good idea to use a gasket now, or just load it up with the high temp silicone?

[DmaxMaverick]

Hey thanks!

So is it a good idea to use a gasket now, or just load it up with the high temp silicone?

NO gaskets. They'll just leak, sooner or later. Use "The Right Stuff" on clean surfaces and be done with it.

[Robyn]

"THE RIGHT STUFF" IS GREAT....A bit more $$$ than the standard hi temp black silicone.

The key to making any of the "GOO IN A TUBE" work well is to be sure that all surfaces are clean and OIL FREE...

Use a clean shop towel and wet it with BRAKEKLEEN...Wipe all surfaces and allow to dry...then apply the goop.

[sdelaney]

Thanks for all the info and advice. For now I'll file it away for later use.

After contorting myself up under and on top I discovered that the leak was in fact coming from a pipe nipple that the PO used to install an after market oil pressure gauge (about 30 years ago based on the appearance of the gauge). The nipple had completely rusted through.

An 89 cent brass plug solved that problem. Whew!:rolleyes:

Thanks again!

[Robyn]

Gawd that's great news

Doing a rear main seal from the bottom up is a sucky job unless you have it on a lift

[DmaxMaverick]

It's a sucky job if you have it on a lift. It's just more sucky if you don't. Great news, indeed.

[Robyn]

At least on a lift you can get to everything and not have to crawl around on a creeper...or worse yet.............IN THE DIRT :eek:

The last rear main I had to do I said noooooooooooooo waaaaaay to the bottom up and yanked the engine out, steam cleaned it well and then went after the beast.

Discovered a weeping freeze plug under one motor mount (Sooooo...that was where the coolant had been going)

Installed a fresh set of freeze plugs and the new rear main seal.....in fact if memory serves me we rolled in new bearings while the bottom was off and dropped in a fresh oil pump too.

The timing cover seal was not stellar so ripped it off and stuffed in a fresh seal and a fresh chain while the cover was off.

The valve covers were a bit oily so removed the fuel injector lines and resealed the covers.

While it was right there it got a fresh set of glow plugs and took the injectors in for a refresh.

Just about everything that is nasty to work on in the chassis was given attention.

Thought about doing head gaskets but the engine did not have all that many miles...maybe 100K at the time.

Ahh well...that truck lasted us 300K miles 1986 K2500 Burb 4x4
Bought it with 30K on it from a dentist who's missus hated the diesel noise. Truck was like new when we got it.

Real good deal that you did not have to dig into your rig very far....That's always a plus...

[sdelaney]

At least on a lift you can get to everything and not have to crawl around on a creeper...or worse yet.............IN THE DIRT :eek:

The last rear main I had to do I said noooooooooooooo waaaaaay to the bottom up and yanked the engine out, steam cleaned it well and then went after the beast.

Discovered a weeping freeze plug under one motor mount (Sooooo...that was where the coolant had been going)

Installed a fresh set of freeze plugs and the new rear main seal.....in fact if memory serves me we rolled in new bearings while the bottom was off and dropped in a fresh oil pump too.

The timing cover seal was not stellar so ripped it off and stuffed in a fresh seal and a fresh chain while the cover was off.

The valve covers were a bit oily so removed the fuel injector lines and resealed the covers.

While it was right there it got a fresh set of glow plugs and took the injectors in for a refresh.

Just about everything that is nasty to work on in the chassis was given attention.

Thought about doing head gaskets but the engine did not have all that many miles...maybe 100K at the time.

Ahh well...that truck lasted us 300K miles 1986 K2500 Burb 4x4
Bought it with 30K on it from a dentist who's missus hated the diesel noise. Truck was like new when we got it.

Real good deal that you did not have to dig into your rig very far....That's always a plus...

Lol,

"While we're in here we might as well . . . "

I had a 1971 Triumph Spitfire that went from chasing down a flickering headlight to a complete rewiring of the entire car, redesign of the dash and dash pad, modern gauges and switches, all because I removed the dash panels and had to remove some gauges (which is a bit of a production) to chase down the defective headlight wire.

"Since I'm in here already anyway . . . " :)

[JohnC]

I had a 1971 Triumph Spitfire that went from chasing down a flickering headlight to a complete rewiring of the entire car...

That was the right thing to do. Or call the exorcist! Lucas, Prince of Darkness.

My Austin Healey had 2 fuses, a 25 and a 50. Headlights didn't work in the rain.

[sdelaney]

That was the right thing to do. Or call the exorcist! Lucas, Prince of Darkness.

My Austin Healey had 2 fuses, a 25 and a 50. Headlights didn't work in the rain.

Yep.

I've seen sturdier wiring on a television remote control. I couldn't believe someone deliberately designed the wiring that way. I was convinced the engineers were drunk and had a contest to create the most inconvenient and impractical wiring possible.

[arveetek]

Lol,

"While we're in here we might as well . . . "

Definitely have to watch those "might as wells!" I pulled a 6.2L out once to replace a collapsed lifter (hard to replace with the engine in the truck). I thought I would "freshen" it while it was out. That one collapsed lifter turned into a complete rebuild including boring it .040 over, custom ceramic-coated lower-compression pistons, timing gear drive, stud girdle, new injectors, injection pump, etc. I was astounded how each decision led to another, all because of "I might as well..."

Casey

[Robyn]

Yup

While we are here

Much easier to get a good job with the engine out

[JohnC]

Yup

While we are here

Much easier to get a good job with the engine out


The moral of the story is "never take the engine out..."

[trbankii]

The moral of the story is "never take the engine out..."

We have a list of rules for working onair-cooled Volkswagens. The first two items:

Pull the engine
Fix the brakes


Seems to be the case for everything that comes in.

To be fair, pulling the engine is disconnecting fuel, coil, alt/gen, throttle cable, oil pressure sender, four bolts/nuts, and then dropping it with a jack - a bit more if you're working on a bus. So it's easier to drop the engine to work on it.

[Robyn]

Getting the engine out of the GM trucks is not all that hard.

The resultant ease of doing the pan, rear seal and other things while in there is well worth it...

Not to mention the color of the air surrounding the truck :rolleyes::rolleyes: :D

[More Power]

"While we're in here we might as well . . . "

Sounds like most "honey-do" projects... :)