Rear Main Seal

[Mad_Trbo]

Ok so I got the car running oil pressure is up and everything is looking good. The only issue I have now is the rear main seal seems to be leaking.

I took the pan down and what a pain in the a$$ that was, so I went to GM and bought some of that special gasket maker stuff. Cleaned everything really well and sealed it back up and I am still leaking.

I have the neoprene seal offset slightly and it appears to be leaking from where the cap meets the block on the driver side.

I used the black RTV sealant to seal the side pockets. I let all RTV applicatoins cure for 24hrs before cranking it again.

Can anyone offer any special advice on getting this done. I'll pull her one more time tomorrow night and if it doesn't seal. I swear I am going to sell it.

 

[terryjh6]

leak

i just had my rear main replaced last week (475.00) jamie had to remove the rear main cap to replace the top of the seal (2 peice) as you know, and damn if the whole top seal was missing! yeah...it was a bad leak you may want to remove that cap and check

 

[Harry Mash]

Did you register the cap up against the block with a dead blow hammer---you may even use a small block of wood and a ball peen ---- but be sure the cap is registered flush up against the block before you start to incrementally tighten the bolts. Also be sure to get all the old RTV out of every nook and I recall putting a little RTV on the caps where they flush up. After you get the caps on squeeze hard on the RTV tube and fill until Rtv is coming out of every possible joint --- wipe the excess --- leave the pan off to help in drying and don't move the crank for at least a day or two.

 

[Mad_Trbo]

Did you register the cap up against the block with a dead blow hammer---you may even use a small block of wood and a ball peen ---- but be sure the cap is registered flush up against the block before you start to incrementally tighten the bolts. Also be sure to get all the old RTV out of every nook and I recall putting a little RTV on the caps where they flush up. After you get the caps on squeeze hard on the RTV tube and fill until Rtv is coming out of every possible joint --- wipe the excess --- leave the pan off to help in drying and don't move the crank for at least a day or two.

All good advice, do you know if you have to use the special RTV from GM the kind that does not require air to cure. I used this and must not have applied enough. Seems as though you are saying it is ok to use regular RTV in all places you would use RTV.

Yeah, I let it cure for 24 hrs before I moved anything. I wonder if this is really necessary?????

 

[Woody]

I used (and it is recommended) Permatex Anaerobic gasket maker to fill the side holes........no leaky.

 

[Mad_Trbo]

I used (and it is recommended) Permatex Anaerobic gasket maker to fill the side holes........no leaky.

Funny when I went shopping for this, few knew what I was talking about. But I'll get it done right tonight.

 

[jjvites]

Did you put a very thin layer of RTV on the surface of the cap that meets the block? If not then you could leak oil between cap and block. Years back I did a little test with different RTV's by putting a small blob of each on a table top and letting it cure. Days later I checked the pliability of each and the one that was most "rubbery" without letting go was the Fel Pro brand. Had to order it from a parts store in a tube for caulk gun but that's what I used on my engine rebuild 5 years ago and still no leaks.
By the way, are you sure it isn't your intake manifold leaking down the back of the block and appearing to be from the rear seal? This is a common problem with the Buick V6.

Marty

 

[Mad_Trbo]

Did you put a very thin layer of RTV on the surface of the cap that meets the block? If not then you could leak oil between cap and block. Years back I did a little test with different RTV's by putting a small blob of each on a table top and letting it cure. Days later I checked the pliability of each and the one that was most "rubbery" without letting go was the Fel Pro brand. Had to order it from a parts store in a tube for caulk gun but that's what I used on my engine rebuild 5 years ago and still no leaks.
By the way, are you sure it isn't your intake manifold leaking down the back of the block and appearing to be from the rear seal? This is a common problem with the Buick V6.

Marty

I thought I put a thin layer, but mayble I didn't cover enough. It looked as though it was only supposed to go in the corner. So I'll go back and do it again additionally I will check the manifold. Thanks for the tip.

 

[Lee_Burough]

You may find some help Here.

Good Luck

 

[Harry Mash]

It appears you have received lots of good advise on the infamous "seal" subject-- to emphasize-- put some RTV on the cap where it meets the block. Also yes I used regular Permatex ultra black #598B and no leaks---good luck

 

[Mad_Trbo]

It appears you have received lots of good advise on the infamous "seal" subject-- to emphasize-- put some RTV on the cap where it meets the block. Also yes I used regular Permatex ultra black #598B and no leaks---good luck

Definitely seems as though there are a myriad of methods to getting this to work properly, but it definitely seems to cause it's share of headaches.

I went over to Napa as advised by Jack Cotton and got some of the Permatex Right Stuff . Jack advised this stuff sets up quick and the instruction indicate you can turn your car immediately back to service. I also purchased some Anaerobic Flange sealant manufactured by Permatex as well as the Permatex gasket remover and then Permatex Gasket prep.

I have now just contributed all I am going to contribute to Permatex's bottoms line for the next 24 months and hopefully I will be blessed with a dry seal.

Thanks for everyones assistance and hopefully this thread brings to gether all the potential fixes for this issue.

 

[Bob Avellar]

Well you know-all that oil that leaks out of the seal and then covers the underside of the body at highway speeds has the benefit of preventing rust on the floor pans. :wink:
Seriously, I have done several and have used many of the methods listed here and elsewhere and I haven't been able to prevent a leak from returning eventually. Maybe boost pressures around 25-26 psi and my pcv valve contribute to the problem. I just have not had much success. I guess that's why I have a power washer and rags. I'm sorry I didn't have anything constructive to contribute. I am curios how many mile people typically get out of them though before they leak again.

 

[turbo39151]

Just did the gn recently. Less leaking but still a tiny leak

Oil leaking is apparently sweat from all of the horsepower :biggrin: Or so I'm told...