[medic]

I ran my 455 for about 10-15 min after i replaced the rear main with a viton seal, I lost about 1/4 quart from the rear of the motor befor I shut it off.It was starting to leak pretty good right befor I shut it down. I have again pulled the motor and when I pulled the pan found the rear cork gasket was not quite in position. Also when looking at the crank and main cap I really dont see anything wet with oil.

So my question is IF i did have a rear mail leak with the viton seal what would be a generalized amount of oil lost in that time frame and how long woul it have taken for the leak to start?
Also would not the oil be flung around the end of the crank and the backside of the motor wet with oil?

Thanks in advance for your help.

Medic

[medic]

I ran my 455 for about 10-15 min after i replaced the rear main with a viton seal, I lost about 1/4 quart from the rear of the motor befor I shut it off.It was starting to leak pretty good right befor I shut it down. I have again pulled the motor and when I pulled the pan found the rear cork gasket was not quite in position. Also when looking at the crank and main cap I really dont see anything wet with oil.

So my question is IF i did have a rear mail leak with the viton seal what would be a generalized amount of oil lost in that time frame and how long woul it have taken for the leak to start?
Also would not the oil be flung around the end of the crank and the backside of the motor wet with oil?

Thanks in advance for your help.

Medic

[Big Mike]

If the cork gasket had slipped out, I'd say you found the leak. If the seal has a problem, many things could affect the rate of leakage. How badly might the seal be damaged? Was it installed correctly? Did you use too much silicone or no silicone for anti-rotation holes? Too much silicone might block the drain path into the pan. The weight of the oil may come into play also. I'd say you could have just a small leak or a large leak depending on the above scenarios. One thing for sure, If the rear seal was leaking, you would probably have oil all over the place.

Big block? Small Block? Nope, It's a Pontiac Engine!

[SupergasDil]

And make sure it fits right when it's in place. I still had to trim about 1/16 off for a good seal. With the caddy seal it was about 1/4" too big and needed a lot more trimming

[burch]

I can say that if the rear oil pan seal (cork, rubber, whichever one you use) is out of place you will have a HUGE oil leak.

I had three of the 3-tit rubber seals fail on me in a row. I had oil EVERYWHERE, but then again I drove the car about 70miles with the seals leaking each time (roundtrip to work).

I'd definately suspect the oil pan seal before the rear main, especially if you're using the BOP seal.

Here's a shot of one of the failed oil pan gaskets:

[medic]

I kinda agree with everyone about the oil pan, but its such a pain to pull the motor again if it isnt it. Is there a way to test it without putting the motor in.

[Old Man Taylor]

Fill the pan with oil and tip the front of the engine up as high as you can. If the leak is bad you will see it.

http://www.jimspontiac.homestead.com/Index.html

[KS circutguy]

**** can the rubber ends, use the cork, gaskacinch it to the pan. Little bit of good old GM silicone on the ends.
It won't leak.
Retorque a few times after heat-cold cycles.

http://photo.starblvd.net/zanko20

Can you hear me now?

[medic]

well I went and pulled the pan, the cork gasget was off a little but not enough to leak at all, but went ahead and replace the gasket and left the viton seal alone. Put oil in and tilted it backwards, the leak was almost instant. So went and tracked down another pan seal, pulled the pan, rear main and put in the rope seal. Got the 455 back in the car will start it up as soon as the radiator gets done.
Looked at the seal, It didnt apper to be damaged or burned so I have no clue.
Medic

[kaptmikey]

I'm going through the same problems and just pulled my engine, the bottom line was mine didn't leak with the front end jacked up as far as I could get it, but drive the car and oil was everywhere. What I finally did after I replaced the pan gasket and still had the same problem was to add a fluorescent additive, giving to me by a local gearhead, and ran the car around town a bit and then hit it with a blacklight. The leak was a no brainer, rear main seal. We'll get it right yet and the guys at BOP have been super supportive. Good luck

[medic]

Just started up the 455, the rope seal holding like a champ.

[Z Code 400]

From what I have seen on the Pontiac blocks I have here in my garage, there isn't a lot of cocentricity to the rear main bearing seal groove.

I have considered the BOP seal, but I am not sure it is the best choice for my 400.

On Fords, we always put the the seals in the block offset 3/8" on opposite sides, so that the mating halves are not aligned with the parting line in the rear main bearing cap.

I would think this method a good choice for the Pontiac, especially if the rear seal groove doesn't appear round.

I have also looked at the anti rotation holes and beleive that a product like Loctite 574 Anerobic Flange Sealant might be a better choice than silicon RTV.

RTV seems to work well when used in small amounts, but I have seen it develop leaks when used in large quantities. An example of this is the elimination of the end seals on the Small Block Chevrolet Intake Manifolds.

Every time I have seen this sealant used at this location, a leak has developed after extended use.

I think that an anerobic sealant would be a better choice in the anti rotation holes than RTV.

What do you think about this???...Robert

[Robert Williams]

Medic, give that rope seal a little more time and it will leak. If the rope seal you installed was made in the last 7 or so years then it has fiberglass in it, not asbestos. The fiberglass will not hold the preload, it will break down and leak big time. Rob, you have a good idea there.

Robert Williams

[PONTIAC DUDE]

Then you won't experience leaks.

I use that type of silicone exclusively for the past 8 years. Even in place of timing cover gaskets, rear pan gaskets, etc, and with the aluminum valley pans too.

************************************************** ***************************

Build it fast, build it right, build a Pontiac.


http://PontiacDude.cc

[Larry Navarro]

had the cadillac seal installed offset of the cap parting-lines, in my old HO motor.
no problems.

1973 SD455 T/A
1979 S.E. T/A
http://community.webshots.com/album/16587603rOyvmFCiHs

[Z Code 400]

Cadillac seal??? What have you been doing, Larry???...Robert

[Wade Congdon]

The cadillac does not properly fit the seal groove making it very difficult to fit. If you cna fit it perfectly perpendicular to the crank it will work. This was done in the past by building up the seal groove with silicone or a similar product. Several articles were written on this installation by Jim Taylor. He now uses the BOP seal.

As far as offseting the parting line, we consider it optional. SOme like to do it others don't. We have yet to hear of a problem either way.

Medic, if you lost a quart of oil in 15 minutes, something was seriously wrong! Was the seal damaged when you inspected it? If not, I can't see how a leak of this magitude on a 400 seal could be possible with the exception of the seal being installed backwards. Hope your rope holds.

Wade Congdon
BOP Engineering
Hi-Performance Specialty Parts for Buick, Olds, and Pontiac
www.bopengineering.com

[medic]

Wade it was about 1/4 quart of oil in 15 min on my 455. when I pulled the motor and seal again i looked at it. really did not see any thing wrong with the seal. Did not look burnt or damaged. I tossed it anyway because pulling the motor 3 times in a month is a real pain. I am not bashing your product, but I also dont need to pull my motor that often.
Robert