engine rear seal

[VileZambonie]

I just looked it up on autozone.com $8.99

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VileZambonie:

Thanks for clearing things up about the gasket; so now I know
NOT to order a one-piece gasket from ebay because the one
mentioned will NOT FIT the 4.3L motor / oil pan (wish there
was one that did, though.) Also the tip about the double and
offset lip seal is good to know. Autozone has quite a selection f
or my model/year and I didn't know which to pick; now you
explained why.

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Dear SgtDel / VileZambonie

OK the ebay seller said if I've the two-piece rear seal, the one piece gasket
SHOULD fit the 4.3L (but maybe he doesn't really know) and yet you say they
are different / not a dealer item. So I guess I want to be 100% sure if it will
or won't fit. Do either of you know for certain? Sorry to be such a pain about it.
I'd like to go with a one-piece oil pan gasket, no goop, if that's possible.

[VileZambonie]

The 4.3L is a V6 the 5.7L is a V8 so the pan is going to be longer on the V8. Use the method I described and you'll see there is no problem putting on the standard oil pan gasket. Just glue all the seals correctly in place. Run a small bead of the right stuff across the end seals over lapping onto the side rail gaskets. Install ALL the bolts and then tighten them criss cross to specs and you'll have no leaks.

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OK, Thank you again! You guys are great!

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Gents:

Has been a while, back again to report my progress (or lack thereof.)

Have had my oil pan off more times than I care to tell, after changing the
rear seal, and still leaks at the dip there, between the pan and bell housing.

Yes, I'm sure the seal lip is pointed in the right direction, installed it slightly
offset and joined the ends with silicone.

Used the 3M weatherstrip adhesive (great stuff) on all bolt holes and none
of them leak. I did NOT use any adhesive where the rubber pan seal joins
the flanges, maybe that was my mistake, but I didn't want to make it too
difficult to remove just in case I needed to do it again! Two questions tho:

Even IF the rear main seal leaks, shouldn't the oil pan contain it?

What IS the recommended torque? Somewhere I read 12 ft.lbs. while my
book says 80 to 165 ft.lbs(!) My experience is that the higher torques
totally destroy cork gaskets so they leak. This time I only tightened as
snug with one hand, and leak-tight all but the place mentioned. I know I
need to do it again, but I hope it's the last time.

[VileZambonie]

DO NOT put any sealant on the rear main seal. Just lubricate it well. in the corners of the rear main bearing cap you can put a teeny weeny itty bitty dab. Torque the rear main bearing cap to 80 lb-ft (on 4 bolt mains the outters are 70). If you do use a little dab of rtv under the cap use a pocket screwdriver to completely scrape out any excess. Install the oil pump and driveshaft. You should upgrade to a steel sleeve shaft. Torque it to 65 lb-ft. No gasket or sealant there either. Using the yellow snot glue the pan rail gaskets into place and use a few bolts to hold them there while the adhesive dries. Glue in the end seals making sure the tangs are fully seated and they are installed properly. Put RTV (the right stuff is the best) across the rubber end seals overlapping onto the pan gaskets. Install the pan and all of the bolts just to get them started. Once ALL the bolts are in start snugging them down with your 1/4" drive ratchet so you don't overtighten them. Torque the 1/4-20 bolts to 80 lb-INCH (not lb ft) and tighten the 5/16 bolts to 165 lb-INCH. Double check all your bolts again and wipe off any excess RTV. IT won't leak this time especially now that you're a pro at it

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Dear VileZ:

Thanks for clarifying what you have.

Q: So are you suggesting a person, by possibly using too much RTV on the seal itself,
could prevent the bearing cap from seating properly, thereby the seal leaking? I don't
THINK I made a mistake here, and DID torque the bolts to the rates you said.

More likely, my omitting RTV across the rubber end seals is the cause of leak. Wouldn't a leaky
rear seal still be captured/covered by the pan itself? (Engineers could have made things easy.)
Reason I ask is really don't want to remove the bearing cap and do the seal over, if I can just
remove the pan again, apply goop to the pan end seals and bolts, call it done. Thanks again.

[VileZambonie]

Don't use RTV on the rear main seal.

The rear main seal is designed to prevent leakage around the rear of the crankshaft. It's not insed the oil pan. If oil leaks past the seal it will exit rearward of the crankshaft and end up running down the back of the engine.

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My pan is off (again) as I write this, 3M adhesive drying in the summer sun.

I noticed the leak was coming from the rubber oil pan end-seal next to the
bell-housing, specifically leaking THROUGH the weatherstripping adhesive. This
time I  built up several layers and allowed to dry a goodly while before bringing
the parts together. The tube says oil-resistant but what was inside the pan last
time does peel away pretty easy. I'll let it dry overnight before adding the oil
back in.

I noticed the rear rubber oil pan end seals DO join ahead of the rear seal, so
technically (at least in the '85 V6), a leaky rear engine (crank) seal shouldn't
even be noticed; it SHOULD dump into the oil pan. At least I can see now that
changing the engine/crank rear seal a third time won't be necessary and probably
wouldn't help much.

I think it's the leaky rubber oil pan end seal that lets it escape. I'll use the
"Right Stuff" over the cork tangs and rubber seal per your suggestion. I didn't
know a sealer was needed there and probably (another reason) why it leaked
on that end.

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UPDATE:

I checked my work today after driving about 10 miles, end results being, still leaks;
not a lot but as much as ever (half a shot to a shotglass ful per night.)

I still can't see exactly where the leak is between the pan and bell housing but assume
the oil is pushing through the 3M adhesive holding oil pan rubber end seals in place. The
rear one is obscured by the clutch shroud but the front one is wet. (Note I did use a
generous bead of "The Right Stuff" over the cork tabs and rubber end seal surfaces this
time so presume that's not the problem. Therefore to solve my problem is I believe I must
find an adhesive/sealant that adheres strongly to metal AND the silicone end seals. Oil
"resistance" means nothing, it must be oil IMPERVIOUS.

I've been on this forum too long, asking for help on this one issue, and yet I still need it.

[VileZambonie]

the rear main seal does NOT leak into the oil pan if it leaks. It leaks behind the crankshaft and down around the back of the engine. If you are sure your oil pan seals are seated correctly and flush and you installed everything correctly torqued to specs yet it still leaks then get a new oil pan.

[Lt.Del]

I am no 4.3 expert, but I agree with Vile on this one.  Rear main seal will leak on the exterior of an engine.   I would look at that rear main again.  Did you coat it with oil before sliding it in place and bolting the cap back on?  If you don't it will burn from friction on first start up and leak. Did you put the "V" facing front of engine?  Hopefully you didn't touch the new seal with anything metalic, like a screwdriver to push it up.  The slightest nick will cause you to invest in an oil company.

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SgtDel & VileZ:

Thank you for getting back to me.

It's always possible I made a mistake replacing the rear main crank seal, but I don't think
I did; (changed it twice.) Anyway the rear seal is under the rear main bearing cap, which is
under the oil pump, which is all confined inside the oil pan. The oil pan / end seals enclose
everything. So even if the rear engine seal were leaking, it must leak past / through the oil
pan end seal to be visible. It would have to leak through / between the end seal and the 3M
adhesive and / or "Right Stuff" goop. I'm not sure a new oil pan would help because i don't
understand how the original could fail. I didn't hit anything. It just started leaking out of the
blue. I think I need to find a sealant to attach the end seals that's absolutely impervious to
oil and won't let it out. The 3M adhesive is good for attachment purposes but it's not impervious.
I can't speak for the "Right Stuff" material but I'll know how easily it peels away when I remove
the pan again (like the 8th or 9th time.)

[VileZambonie]

The crankshaft sticks out of the engine block. The rear main seal's job is to keep oil inside the crankcase. If it leaks past the seal it will exit right where the crankshaft exits the engine block. If it is your rear main seal leaking after you replaced it then make sure you don't have excessive crankcase pressure. Are you sure it isn't leaking from somewhere else up above? Like the intake manifold or oil pressure sender and just running down the back of the engine? Is it wet above the oil pan area?