# Sticky  Rear main seal info



## jetstang (Nov 5, 2008)

OK, I've read all the threads saying to go with the Viton Seal. I have my engine on the stand putting it back together. I have a Felpro Gasket set with rear mains, which I've read aren't worth using. Then there are the new composite rope seals. OK, so I have a 70 350 that was taken out 15 years ago at 100k for upgrade to a 400, no issues with motor. The flexplate mount is clean, no oil residue at all. If the original seal didn't leak, what is the chance that it won't leak if I just leave it alone. I was trying to button the motor up today, but got the wrong oil pump, so back to the parts store.

And, what is the proper way to install the rope seal with the crank in?
Thanks.


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## 68greengoat (Sep 15, 2005)

I would be proactive and replace it now since the engine is out. I've heard the new rope seal is nothing like the old ones and does not leak. They featured it on one of the car fix-em-up shows on tv. Although, everyone seems to rave about the Viton which is probably what I'm going with when I decide to replace it.

I would like to see a sticky on the process, w/pics, of changing out the rear main....


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## geeteeohguy (Feb 2, 2008)

There IS no proper way of installing a rope seal with the crank in. I too have read about the new square-cross-sectioned rope seals....I forget the name, it was on the PY forum...Graf-tight? Graph-seal? The round ones that come in the kits are no longer the ones to use....they contain no asbestos, and leak. I bought a Vitron BOP seal for my '67, (still not installed), but I didn't know about the new improved rope type. You can install the Vitron seal with the crank moved up a little, main caps off. Not a seal to shortcut. Better off doing the extra work now, and avoiding the dreaded drip!!


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## geeteeohguy (Feb 2, 2008)

I just checked. It's "Best Gasket Company", and they sell a "Graph-Tite" square rope seal. Seems to be the new big thing. Check it out online, and good luck!!


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## Chris Holabaugh (Jan 18, 2009)

When my current engine builder tour down my engine because rear seal was leaking. The previous shop had put in a new rubber seal that has the spikes on it, I can't remember the name. The problem was they got permatex or something else on it, and it made it leaked like a sieve. So when up put a new one in be sure nothing gets on the seal.


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## Rukee (Feb 8, 2007)

You have to seal the ends of the two halfs of the seal under the main cap or it will leak for sure.
Also it's best to have the crank out, or at least remove the rest of the main caps to be able to lift the crank slightly to get the block half of the seal in.


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## jetstang (Nov 5, 2008)

I just ordered the graph-tite seal off Ebay, will be in next week. So, will post how the install went and then how it worked after install and running, hopefully within a couple weeks, or not. Hopefully it comes with good instructions, would hate to go through all this and have it leak....


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## geeteeohguy (Feb 2, 2008)

Jetstang, with a rear seal , the concensus is: they either leak right away or they stay oil tight. The one in my '65 has been oil tight since about 1981 when I put it in there. I just drove the car this past weekend. Still no oil leaks, 29 years later. My '67 leaked within 1000 miles of the seal install in '88. It leaks like a sieve, now. I'm planning on upgrading my shop situation in the next 18 months or so. I'll fix it then. I'm getting too old to gravelback a rear main these days, and seeing everybody else's shops/work areas, complete with forklifts and toilets, has me all a-twitter. Good luck with your project. I think you made a good choice, as I have a gut feeling (besides all the good press) that the graph-tight seal will work very well.


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## jetstang (Nov 5, 2008)

The worst part is I don't really care if it leaks a little, just wipe it off during an oil change, wish I wouldn't of read up on it, stuck the motor in and worried about it later, lol. I may just stick it in as is with the 40 year old seal and cuss later. But, use the new seal on my 400 when I freshen it up. 
Seals in the mail, so will install it as I'm waiting on other parts anyway.


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## johnnylightning03 (Nov 27, 2007)

i went with the viton in my 66 389, i have run the motor quite a few times, but havent driven the car yet, very soon though. so far no leaks. i loosened the main caps to get it in and followed the installation instructions. you have to measure how far it sticks above the block and cap with one side flush and the other side up, trim as needed and silicone the ends. i'll report back if i have any truobles.


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## Too Many Projects (Nov 15, 2008)

You may not be able to do the rope seal like this but I've always clocked a 2 piece rubber seal about 10° off plane. That way the ends are contained in the cap and block and not right at the cap seam. I still use a DAB of sealer at the joint and have had VERY good experience with no leaks from this method.


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## jetstang (Nov 5, 2008)

I talked to my engine builder buddy today, he has used Felpro seals and has never had a problem with them. He said clock them 3/16" out and put a little sealer on them and he has never had a problem, but he builds mostly BBC/SBC and Fords. But, this is a GTO forum, the 1%ers, and understand that you guys don't except a drip, lol.. I just made up the 1%er thing, figured that 1% would realize my 66 GTO Cloan isn't real, 99% would think, "Nice Chevelle"... OK, most would see GTO and think it's real.. I started checking Vins, 242, at the last car show just to see if they're real, trying to be a 1%er...


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## jetstang (Nov 5, 2008)

I put the best Gasket in it today. All said you only have to lift the crank 1/2" to get it in. Hell with that, I pulled the crank out and did it right with the pistons in the motor and heads on, just pushed them down. Hopefully I didn't hurt anything, motor turns fine. The gasket I used said not to presoak, just install and put some assembly lube on the outer seal. I had to torque the main back in to get the seal to seat. Pretty straight up job, just pull the crank out and crush it into place. I wouldn't even try it with the crank in, not enough room to work and you can't inspect what you did.


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## geeteeohguy (Feb 2, 2008)

Jetstang, I agree with you on the crank thing. Why not spend a couple of minutes extra to KNOW that you have the seal seated properly and nothing's pinched or tweaked. We're crossing our fingers that it won't leak. Pulling and reinstalling the crank will not hurt a thing, as long as you retorque the main caps and rod caps, and kept them in their proper order.


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## Rukee (Feb 8, 2007)

jetstang said:


> I put the best Gasket in it today. All said you only have to lift the crank 1/2" to get it in. Hell with that, I pulled the crank out and did it right with the pistons in the motor and heads on, just pushed them down. Hopefully I didn't hurt anything, motor turns fine. The gasket I used said not to presoak, just install and put some assembly lube on the outer seal. I had to torque the main back in to get the seal to seat. Pretty straight up job, just pull the crank out and crush it into place. I wouldn't even try it with the crank in, not enough room to work and you can't inspect what you did.


The only other thing I would have like to have seen you done was to pull the push rods out so all the valves were closed. Shoving a piston up to an open valve can be costly.


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## jetstang (Nov 5, 2008)

Rukee said:


> The only other thing I would have like to have seen you done was to pull the push rods out so all the valves were closed. Shoving a piston up to an open valve can be costly.


Oh, I backed all the rockers off, I thought that out. I didn't hurt anything. Wish I would of bought new rod and mains and done them while I was in there, pretty stupid not to, but needed to order them and didn't think about it prior. And I could have had the crank polished, blah blah blah. Coulda woulda shoulda...
I wasn't rebuilding, just freshening up, so all is good.
Pontiacs are odd, rod caps only go on one way, if you mix it up, they will hit the next rod cap, weird and nice. I guess they offset drilled the cap.


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## jetstang (Nov 5, 2008)

For timing cover/water pump mount, one of the long bolts snapped off flush with the cover. The corrosion is so heavy I can't get the aluminum cover off teh front of the motor. Any ideas to free it up without breaking the cover? I am thinking to center drill the bolt, maybe the heat from drilling will free it up. I have another cover, but the guy I got the motor from had swapped the original for it as it leaked or something, don't want to use a suspect bad cover. Can you sand the cover flat or how do you tell if its' bad beyond corroded, thin surfaces?


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## jetstang (Nov 5, 2008)

Here's the pics of the install, remove crank, not enough room to work under it. Install rope seal, mush into place with socket extension. Trim ends with 1/16" spacer and popsicle stick. Push all exposed brading towards center of seal. Do same for top cap. Reinstall crank, caps and be carefull with rods as to not nick crank. There is no way to seat the seal properly in the rear cap with the crank in. Retorque all to spec. I had the crank up out of the block 1/2" and still couldn't see where I was working at and couldn't get good access due to the flexplate mount on the back of the crank, that's why I pulled the crank. For the best gasket, it says do not soak in oil, don't rtv it to the block or ends. Do install assembly lube to the top of the gasket where it hits the crank.








This is the best gasket brand, graphite impregnated, nice gasket. I believe this is for the larger crank motor, note the excess, I forgot to specify when I ordered it.








The 1/16" shim gives you the mating surface between the upper and lower. Center the excess on both sides. When you try to cut the short side it wants to fray, the longer side cuts really nice.


























When reinstalling the crank, you have to put the 2 connecting rods on the lowest crank journal while you are dropping it in. The rest can be reinstalled on the crank with it in the motor. 








Oh, and if your kickdown cable is freyed and you are pulling hoses off, be carefull, those wires are sharp and hard, and you have to cut yourself free from the car...


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## 66tempestGT (Nov 28, 2009)

:willy::willy::willy:


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## Rukee (Feb 8, 2007)

I *HATE* it when that happens!!


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## 68greengoat (Sep 15, 2005)

Rear main seal pix. Cool! And, ouch..........


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## geeteeohguy (Feb 2, 2008)

That happens to OTHER PEOPLE too? Whew, I feel a little better. Martini-olive-skewered digits are never a fun thing. That looks like a great seal, way more confidence inspiring than the cheesy rope seals that come in the kits. The rest of the engine looks fine, too. I'm betting it won't leak.


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## jetstang (Nov 5, 2008)

I was impressed with the seal when I got it, as I compared it to the Felpro rope seal. I'm hoping it doesn't leak, and I'll put enough permatex on everything else so it should be good to go for a long time. The old pan gaskets were rock hard and brittle, they wouldn't of sealed at all. The engine was already on the stand, but pulling the crank, installing the seal and retorquing only took a couple hours, not a bad job. The worst part was making sure the rod bearings stayed where they were supposed to be while reinstalling them. Make sure none of the main or rod caps get turned or out of order. Also, make sure to mark the number on the rod caps if it hasn't been done before, as mine hadn't.


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## Too Many Projects (Nov 15, 2008)

Nice job on the install and pics.....
I hope you cut the excess off the wire before you pulled it out.....:willy: That sh!t happens so fast, like when I ground my thumb, that you just stand there and think...how the he!! did that happen ?? That pic brings back too many bad memories and it's gonna hurt for a while....


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## jetstang (Nov 5, 2008)

Too Many Projects said:


> Nice job on the install and pics.....
> I hope you cut the excess off the wire before you pulled it out.....:willy: That sh!t happens so fast, like when I ground my thumb, that you just stand there and think...how the he!! did that happen ?? That pic brings back too many bad memories and it's gonna hurt for a while....


Or when you filet your finger open and look at the open wound before the blood starts running going oh damn, this is gonna hurt...

Actually, I was stuck by myself under the hood of the car and NOBODY was around. I didn't have any dikes to cut myself loose, so bent it back and forth and it didn't break-painfull. After about 10 minutes being stuck I looked on the cowl and found my savior needlenose, bent it back and forth about 5 times and it snapped, yeah!! Then, thought about the hospital or cutting the skin open. Finally, thought about peircings, so I Iced it up til I couldn't feel it and pulled it out. Dirts still in my skin, I can see a line, but no infection, so I am good. I do have a metallic taste in my mouth all the time, hmm, wait, I was just grinding, that explains that.:cheers


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## Too Many Projects (Nov 15, 2008)

That's what I did with the thumb gash but the wheel was spinning so fast it cauterized the sides and it never did bleed. Interesting watching the muscles and tendons working when you move the finger....

When was your last tetanus shot ?? I manage to get one every few years with my injuries....


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## jetstang (Nov 5, 2008)

Too Many Projects said:


> That's what I did with the thumb gash but the wheel was spinning so fast it cauterized the sides and it never did bleed. Interesting watching the muscles and tendons working when you move the finger....
> 
> When was your last tetanus shot ?? I manage to get one every few years with my injuries....


Haven't had a shot for a while, might have to get one, and then keep it current.
Bet that taught you to keep your fingers out of the grinders. I wear my hand scars as a badge of honor.. That liquid bandage works pretty good, but it burns.
Woo hoo, I got stickied!!
I am continuing to update the pic post as I have time, make it better.


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## gtomuscle (Dec 11, 2009)

Ouch been there:willy:


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## johnnylightning03 (Nov 27, 2007)

ouch!  good reason to change over to a stick and eliminate that cable.


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## khinton (Jun 22, 2008)

I used the Best Gasket, Grafite seal--installed a year ago when I did a complete refresh--car has only about 1200 miles but no leak at all so far. Comes with directions; easy to understand--Had the motor out on a stand and all moving parts out for a complete refresh--I would recomend this seal--you will see the diference between this and the orginal rope as soon as you look and feel it


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## geeteeohguy (Feb 2, 2008)

Thanks, Khinton. Looking at the website info and the photos, that's what I expected. I also have been reading testimonials from users like yourself who give it the thumbs up. I have a BOP rubber seal for my upcoming "project", but am considering using the Best Graftite instead, because it appears really user -friendly.


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## Too Many Projects (Nov 15, 2008)

geeteeohguy said:


> Thanks, Khinton. Looking at the website info and the photos, that's what I expected. I also have been reading testimonials from users like yourself who give it the thumbs up. I have a BOP rubber seal for my upcoming "project", but am considering using the Best Graftite instead, because it appears really user -friendly.


Since you already plan to extricate the engine for the seal change, it might be a better seal. Just do like Jetstang and gently push the pistons down the cylinders out of the way to remove the crank. Just be sure to use a set of "booties" on the rod bolts. I once changed the crank in a 76 Cutlass with the engine in the car and have a set of 16 of them......


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## Rukee (Feb 8, 2007)

You can just use pieces of 5/16" fuel hose too if you don't have those fancy boots.


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## Too Many Projects (Nov 15, 2008)

Rukee said:


> You can just use pieces of 5/16" fuel hose too if you don't have those fancy boots.


Maybe vacuum hose, but I had trouble getting the heavier wall fuel hose to slide past the journal. The thin boots have room to spare and they're cheaper than vacuum hose at 1.30/pair...:cheers
I'll mail them to you, if you want Jeff....


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## geeteeohguy (Feb 2, 2008)

Thanks, Mitch, but I already have 'em. Mine are bright red "generic" boots that work great. Fun fun!!!


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## dimitri (Feb 13, 2009)

Don't forget to put a small bead of sealant on the block from the main seal outwards before putting cap back on.


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## JeffW (Aug 30, 2009)

*I must be jinxed!*

The first time I rebuilt my 400, I used the viton seal. I siliconed at the areas specified in the installation instructions, ... result .... leaked like a bad diaper on a baby. The following winter I installed a new forged crank, so naturally, I installed a new viton seal from a different supplier, it was slightly different from the first one I installed. I even made sure the seal mating surfaces were not on the same plane as the bearing cap. The result was the same. IT LEAKS badly. I'm seriously considering trying the graphite rope seal mentioned in a previous posting. I seriously wish you good luck, and if you accomplish a leak free seal, please let me know how you did it. 

THANX
JeffW


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## jetstang (Nov 5, 2008)

This was months ago, and yes it sealed perfect, no leaks. And no dab of silicone at the mating surface.


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## Glenn's Goat (Sep 7, 2010)

Over the years of done a couple of rear main seals (not on Pontiacs) with out removing the crank. I use a tool that we call "the chinese fingers" You get the top seal out and then you side the wire part of the tool thru the main jounal. You place one end of the seal into the grip part of the chinese finger tool. then you must pull it thru the journal, its not easy sometimes but if you have a buddy turn the crank in the direction your pulling by using a breaker bar and a socket on the balancer you'll get it. Ive done several chevy motors and a couple of small block Buicks that way. No leakes ever. I'm going to attempt it with my GTO 400 engine as for i too have a oil leak. Wish me luck.


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## geeteeohguy (Feb 2, 2008)

Glenn, if you've done it on other cars, you can do it on your GTO. Most don't have the finesse. There is also a bronze tool used to drive short pieces of rope seal into the upper half (in addition to the old seal already in there) and then just the bottom half is replaced. This is an "in service" repair as described by GM.


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## jetstang (Nov 5, 2008)

Good luck trying to push a rope, isnt' there an old adage on that? I guess the cap is actually the seal that would be leaking, not the block side as much, so a fresh lower may do it if you seal the seam. Unless your upper is a rock, then it wouldn't work.


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## geeteeohguy (Feb 2, 2008)

Jetstang, a friend of mine has the GM tool specifically made for this! The trick is to cut short pieces of seal (about 3/8" in length) and pound them in. These pieces of seal are like pellets, and don't fold up on themselves. Me, I think I'd just replace the darn thing 100%. upper and lower. It's like doing a clutch job and leaving in the old throwout bearing. False economy!!


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## 66tempestGT (Nov 28, 2009)

my dad has a tool for this that the end looks kinda like chinese handcuffs. you put over the crank, attach the seal and pull it through.


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## geeteeohguy (Feb 2, 2008)

I have one of those, too. I've had it for about 25 years. I have never had the guts to use it. The tool for driving the seal sections into the upper groove is a brass drift with a shoulder on it so it doesn't go too far in. The idea is to force enough rope into the upper cavity that it presses against the crank (it has nowhere to go). That, and a new lower seal half are supposed to fix the leak. My friend with the drift has used it many times with good results, mainly on 3.8 Buick V6 engines "back in the day".


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## Glenn's Goat (Sep 7, 2010)

Well take it from me, its the block (journal) side of the seal that always leak, not the main cap. So if anyone is gonna go thru the trouble of pulling off the pan and attempting a seal replacement, do it once and do it right. Replace the upper and lower. As for the Chinese fingers tool, it does work and it works good. It is'nt easy though. It takes time and a little thought. I will suggest having a second rope seal on hand in case you muff the first one up. As for the upper seal removal, that usually comes right out with not to much problem for it is shrunk and loose. :cheers


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## Topkat (Sep 9, 2010)

Whats the best sealant to use on Graph Tite rear oil seal?
Are the holes in the bottom of the cap to be filled with sealant ?
Do I need to put sealant on the block to cap surfaces as well?
Thank You


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## jetstang (Nov 5, 2008)

The Graphtite doesn't need any sealant. The directions should tell you what lube to put on it.


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## Topkat (Sep 9, 2010)

"Coat all cap to block mating surfaces with sealant."
from GraphTite Instrustion sheet


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## geeteeohguy (Feb 2, 2008)

That tells me that you need to do just that. That means a thin film of sealant on the cap ends and maybe a drop or two where the rope halves meet. Not much at all, and most will squeeze out when the main cap is tightened. If you are still uncomfortable, google "installing a best graph tite seal" and talk to the guys who install them on a regular basis. This is the ONE THING on your engine you must get right the first time.


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## extinctmake (Feb 8, 2011)

I've also been told that to replace a leaky rear main seal on a Pontiac V8, the crank has to be removed.

What about using one of those "Chinese Fingers" seal/remover installer tools? 

Has anyone had any luck using one of those to prevent pulling the crank out of the engine to change a rear main seal?


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## geeteeohguy (Feb 2, 2008)

Extinct, read Glenns Goat's post five posts previous...


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## BearGFR (Aug 25, 2008)

The famous Pontiac Rear Main Seal discussion...... :rofl:

I've read about this topic on so many forums from so many people for so long... that I've come to the following conclusions:

1) Usually, it's better to "do it right" and drop/pull the crank.
2) Sometimes, people are able to "fix" one without having to do that.
3) Sometimes, even the most meticulously prepared block/cap, high dollar seal, and religiously followed instructions will still result in a "leaker".
4) It might help to sacrifice a young goat and arrange it's entrails on the garage floor in a circle around your engine at the next full moon.... 

Translation: there's never a guarantee when it comes to these things, but usually, best results are obtained by using quality parts and following the manufacturers instructions TO THE LETTER.


Bear


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## jetstang (Nov 5, 2008)

:agree Voodoo helps.
I started this link and my 70 hasn't seen many miles, but it has a small puddle underneath it all the time. I'm thinking tranny fluid as it is always a little wet, but it isn't red.. I'm hoping it's the drain plug or filter, but haven't jacked it up.. 
Is the oil level high enough in the pan to actually leak out the seal while it's parked?? Seams like the oil should be in the sump of the pan and not up to or touching the crank at it's lowest point, which is inches below the crank mains..


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## Glenn's Goat (Sep 7, 2010)

jetstang said:


> :agree Voodoo helps.
> I started this link and my 70 hasn't seen many miles, but it has a small puddle underneath it all the time. I'm thinking tranny fluid as it is always a little wet, but it isn't red.. I'm hoping it's the drain plug or filter, but haven't jacked it up..
> Is the oil level high enough in the pan to actually leak out the seal while it's parked?? Seams like the oil should be in the sump of the pan and not up to or touching the crank at it's lowest point, which is inches below the crank mains..


Funny, mine never leaks when it runs, only when it sits for a while. Oil usually leaks down into the tranny converter cover. Then it leaves a happy puddle just like an old Harley Shovel head. Also check your tranny fluid level. Turbo 400's don't like to be over filled, not even a little. The front pump seals usually leak.


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## Instg8ter (Sep 28, 2010)

when it leaks while under load the flywheel is spinning it on to the bell housing and torque converter, so when you park it it will take a while for it to leak down off the walls and form a pool in the cover then leak onto your floor slowly.


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## extinctmake (Feb 8, 2011)

I did catch those previous "Chinese Finger" posts a little tardy geeteeohguy.

I'm interested in this topic because my current engine in my '65 GTO drips a little oil from the rear main.

I've learned to live with it and I regret not replacing it before installing it in my car, but somebosy told me the crank had to be removed and I really didn't want to do that.

Plus I didn't know if the seal would even leak and I wondered if the one I'd put in would leak anyway. 

After reading the posts on this thread it appears I should have bit the bullet and pulled the crank and installed a new rear main seal. I did learn that there are some good alternatives to the old rope seal. 

Great thread.


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## jetstang (Nov 5, 2008)

Instg8ter said:


> when it leaks while under load the flywheel is spinning it on to the bell housing and torque converter, so when you park it it will take a while for it to leak down off the walls and form a pool in the cover then leak onto your floor slowly.


That makes sense. Guess I have to run it, then jack it up to see what is wet.


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## timmyg (Jan 2, 2012)

I have used the Viton Seal On a 350 Pontiac Engine and now have installed in the 455 Pontiac Engine I am putting together. The Viton Seal has worked great in the 350 Engine. I have about 12k miles on it and no leaks. When I installed in the 350 , I had the motor torn down and followed the directions for "Replacing with the crank out of the motor". When I ordered the Seal for the 455 Engine, the Seal came with a newer set of directions which explains how you can install the Viton seal with the Crank in the engine. This is how I installed in the 455 as the motor was fairly fresh when I purchased the car. The only problem was the Rear Main Seal leaked like crazy. (It had the Rope style Seal). If you decide to go with the Viton Seal, I recommend that you order it from "BOP". I called their Tech Support on a Saturday afternoon and the gentleman walked me through the whole process of installing the Seal with the Crank in the engine. Great customer service.


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## jetstang (Nov 5, 2008)

Oh, found out that my speedo gear seal was leaking. As that fluid doesn't really move it was dark and not red. Rear main hasn't dripped a drop!


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## GTO JUDGE (May 14, 2005)

jetstang said:


> Oh, found out that my speedo gear seal was leaking. As that fluid doesn't really move it was dark and not red. Rear main hasn't dripped a drop!


Mine was too, just replaced both gaskets. The leak was actually at the cable gasket.


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## joedee (Dec 13, 2012)

timmyg said:


> I have used the Viton Seal On a 350 Pontiac Engine and now have installed in the 455 Pontiac Engine I am putting together. The Viton Seal has worked great in the 350 Engine. I have about 12k miles on it and no leaks. When I installed in the 350 , I had the motor torn down and followed the directions for "Replacing with the crank out of the motor". When I ordered the Seal for the 455 Engine, the Seal came with a newer set of directions which explains how you can install the Viton seal with the Crank in the engine. This is how I installed in the 455 as the motor was fairly fresh when I purchased the car. The only problem was the Rear Main Seal leaked like crazy. (It had the Rope style Seal). If you decide to go with the Viton Seal, I recommend that you order it from "BOP". I called their Tech Support on a Saturday afternoon and the gentleman walked me through the whole process of installing the Seal with the Crank in the engine. Great customer service.



Hi,

Ok so you did not have to remove the Crank but was the engine out of the car or just jacked up so you could get to it?:confused

Thank you,
Joe


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## jetstang (Nov 5, 2008)

GTO JUDGE said:


> Mine was too, just replaced both gaskets. The leak was actually at the cable gasket.


WHAT?? There's a seal on the cable? Oh, time for a new speedo cable, mine bounces anyway. I resealed the housing 3 times and it still leaks. Good info, thanks.:cheers


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## Too Many Projects (Nov 15, 2008)

jetstang said:


> WHAT?? There's a seal on the cable? Oh, time for a new speedo cable, mine bounces anyway. I resealed the housing 3 times and it still leaks. Good info, thanks.:cheers


I doubt you'll find a replacement speedo cable with a seal in it. The new cable on my '66 Chevelle started leaking and I cut down a garden hose gasket a little to fit and the leak stopped ....

I have two auto trans that leak from the shift shaft seal after they sit long enough for the fluid to drain out of the converter too. PITA...:lol:


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## geeteeohguy (Feb 2, 2008)

The reason the speedo cable will leak is because the nylon output shaft on the gear wears a bit, just like a harmonic balancer shaft will, over time. You can install a new seal, and it'll still leak on drainback, as TMP noted. You can replace the gear, or you can install some old fashioned packing in the housing and/or and addtional o-ring. There are ways to be creative if you want to be. Chasing small oil leaks is a PITA, but it is merely a loyalty test designed by the Pontiac Gods.


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## Tropical Goat (Jan 30, 2011)

Just to help anyone decide...I installed the graphite rope seal (from BOP) around 2 years ago and,...no leaks yet!


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## GTO JUDGE (May 14, 2005)

jetstang said:


> WHAT?? There's a seal on the cable? Oh, time for a new speedo cable, mine bounces anyway. I resealed the housing 3 times and it still leaks. Good info, thanks.:cheers


There is a small O ring on that cable. That O ring came with the larger O ring for the housing. Mine was leaking where the cable screws in to the housing. Installed that O ring and the larger one too while I was at it. Problem solved.


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## Glenn's Goat (Sep 7, 2010)

Has anyone had any luck taking the pan down, the rear main cap off and using the "chinese fingers" tool to remove and replace the factory seal with same?? I've done it on several SM Chevy and Buick engines, never Pontiac.


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## the65gto (Oct 9, 2008)

Glenn's Goat said:


> Has anyone had any luck taking the pan down, the rear main cap off and using the "chinese fingers" tool to remove and replace the factory seal with same?? I've done it on several SM Chevy and Buick engines, never Pontiac.


YMMV - Back in the day (1965) I had the Pontiac Dealer try and replace it (Under Warranty) with their new tool to do an in-car replacement.. On the third day, they pulled the engine to do it.


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## ppurfield001 (Jan 21, 2008)

the65gto said:


> YMMV - Back in the day (1965) I had the Pontiac Dealer try and replace it (Under Warranty) with their new tool to do an in-car replacement.. On the third day, they pulled the engine to do it.



I had the same experience. The rear main seal did NOT seal until the engine was pulled and a Viton seal was properly installed. Good luck.


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## mrbill (Jan 5, 2013)

If anyone is interested, graphite-impregnated rope seal is available through your local industrial plumbing supply house. It is used often to reseal pump shafts. It's good stuff, has a self healing property about it and is easy on shaft wear. One linear foot is enough for a large journal main and should only cost $15-$20/ft. Just a thought from an maintenance guy. example below...

McMaster-Carr

browse "compression packing seals" #14 specifically


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## joedee (Dec 13, 2012)

*Has anyone tried this*

Hi,
Has anyone tried PermaTech stop leak? Does it work or just a waste of money?

Joe


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## GTO JUDGE (May 14, 2005)

joedee said:


> Hi,
> Has anyone tried PermaTech stop leak? Does it work or just a waste of money?
> 
> Joe


No, not Perma-Tech. When I first got my GTO it was leaking both oil and transmission fluid pretty good. I used BarsLeaks in both with good success. It reduced the leaking very well. In time the leaking got worse and upon removal of the pan and rebuilds I discovered the gaskets were shot bad. The barsleaks worked well on really worn dried out brittle gaskets. Many frown on adding this to the oils. I did so as a temp fix ( 1-1/2 seasons) until the issues were corrected. When the trans was rebuilt and engine torn apart there was no evidence of any additive damage or other issues some warned about.


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## JeffW (Aug 30, 2009)

I would strongly suggest AGAINST a viton seal. I decided to upgrade to a viton seal and for three years in a row I pulled the engine. The cause ... The viton seal is Not designed for the Pontiac crank. If you look at the crank shaft where the original rope seal is located, you will see serations cut or machined in the crank. The purpose of this is to keep the rope seal lubricated. Unless you have these serations machined out they WILL leak with a viton gasket. (Trust me ... after three attempts I know.) I installed the graphite/teflon rope seal on my fourth try. The result was great. It does not leak a drop. The only difference with this seal is that you have to drill a couple of holes in the bearing cap and install roll pins or tension pins (which ever name you prefer), to keep the seal from rotating on the initial start up, but this is easy. When you dis-assemble your power plant, just think about it. You have a perfectly round rubber seal and a crankshaft with serations in it and oil circulating for lubrication. Common sense says the oil will leak through the serated areas.


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## 69gr81 (Mar 4, 2013)

Hey, just joined today and have owned a 69 goat cvt for six years. rebuilt engine five yrs ago and have problems with rear seal. thinking of getting the high perf rope seal from ames. 
another problem is no vacuum. car has a/c and power brakes. hardly any assist after installing 041 cam, 1.65 rockers and rhoads lifters. heater valve wont open. didnt ram air 4 cars have power brakes? my motor is similar except d port heads. anyone else come across this problem? running a modified quadrajet and car runs awesome. cant stop though.


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## GTO JUDGE (May 14, 2005)

JeffW said:


> I would strongly suggest AGAINST a viton seal. I decided to upgrade to a viton seal and for three years in a row I pulled the engine. The cause ... The viton seal is Not designed for the Pontiac crank. If you look at the crank shaft where the original rope seal is located, you will see serations cut or machined in the crank. The purpose of this is to keep the rope seal lubricated. Unless you have these serations machined out they WILL leak with a viton gasket. (Trust me ... after three attempts I know.) I installed the graphite/teflon rope seal on my fourth try. The result was great. It does not leak a drop. The only difference with this seal is that you have to drill a couple of holes in the bearing cap and install roll pins or tension pins (which ever name you prefer), to keep the seal from rotating on the initial start up, but this is easy. When you dis-assemble your power plant, just think about it. You have a perfectly round rubber seal and a crankshaft with serations in it and oil circulating for lubrication. Common sense says the oil will leak through the serated areas.


I must have gotten a faulty vitron seal, 3.5 years later and over 5K miles no oil leaks. First time I am glad I bought a defective item. I lucked out.


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## geeteeohguy (Feb 2, 2008)

I have installed the Viton seal in several engines. All have several thousand miles on them and several years since, with no leakage whatsoever. On the engines that I did, the crankshaft serrations did not contact the seal lip. Close, but no contact. I hear nothing but rave reviews on the Graph-tite square rope seal, too.


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## old-goat (Jul 10, 2011)

I installed the Viton seal in my '65, which has a '70 Bonneville 455- I followed the instructions to the letter and guess what - it drips, just enough to leave a quarter size spot every where I park but I worry about it getting on my clutch


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## Rukee (Feb 8, 2007)

It shouldn't get on your clutch as it will hit the back side of the flywheel and get slung off, not the clutch side.


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## old-goat (Jul 10, 2011)

Rukee, That's true the clutch should stay dry...it will have to leak a little more than it is now to justify pulling it down


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## geeteeohguy (Feb 2, 2008)

That's bad news. I have read that with the big journal blocks (421-428-455), the viton seal can be problematic due to the machining methods used at the rear main saddle and cap. The big journal blocks are rougher in that area than the small journal blocks, and have issues with the thin viton seal. If I were to do a big journal, I'd use a graph-tite seal. As I said previously, viton seals work great on small journal blocks.


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## ppurfield001 (Jan 21, 2008)

GTO JUDGE said:


> I must have gotten a faulty vitron seal, 3.5 years later and over 5K miles no oil leaks. First time I am glad I bought a defective item. I lucked out.


:agree


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## timmyg (Jan 2, 2012)

I recently rebuilt a 70 455 engine for my 65 Goat. The engine leaked at the Rear Main Seal very bad prior to the Rebuild. The engine had the old rope style seal. I installed the Viton Seal when I put engine back together. First few hours of run time I only had a couple of drops leaking but after a few drives it is leaking terrible making a mess of the underneath and dripping along the length of the car. Hate to do it but I have to remove the engine and I am going to try the "Graph Tite Seal" from the "Best Gasket Co." I sure hope this does the trick. I had used the Viton Seal on the 350 Engine in my FireBird and it seals good. I agree that The serations on the crank in the area of the seal are probably why a Rubber Lip Seal like the Viton could very well leak. I had followed the instructions on install of the Viton Seal to the letter. I even had a tech from "BOP" who makes the seal walk me through the install over the phone. I think it is a good seal, however it appears that it just doesnt seal in all cases.


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## BearGFR (Aug 25, 2008)

.... and if the engine has been align honed or align bored in the mains, the viton seal will have an even tougher time of it because those operations both result in the seal groove no longer being round, but sort of elliptical. I'm having the same issue with my car. The next time the motor comes out, I too will be going with the Graphtite seal.

Bear


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## timmyg (Jan 2, 2012)

I have got my 455 engine ready to come out in the morning. I will then proceed with removing the pan, crankshaft, etc. When I got my car, the Rear Main seal leaked terrible. It had the rope style seal. I removed the engine and replaced with the Viton seal which I had a tech from BOP walk me through the process of installation. The Viton seal leaked worse than a sieve. Tomorrow I will start the process again of replacing the Rear Main Seal, thus removing the Viton Seal. I am going to replace with the new Graph Tight Seal from Best Gasket Co. I was wondering does anyone have any tips or experience with the Graph Tight Seal that I should know about when installing this Rear Main Seal. I so want this seal to do the trick and not leak. I do not want to go through this again. Is there any thing I should be looking for on the Crankshaft in the area where the Rear Main Seal goes that may be causing the issue, or should I just assume that the previous seals simply did not work. I was wondering if there could possibly be a thrusting issue with the Crank that could be causing the issue. Does that sound possible?? The engine is a 1970 455 HO. Crank has 10 under Main Bearings installed. As always, any advise is appreciated.


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## Mark 68 (Jul 27, 2013)

*BOP seal is great*

After having a 455 with a leaking rope seal I switched it out to a BOP Engineering seal and not a drop. I just build a 400 and used the same seal and agter 1,000 miles still not a drop. Why take a chance with anything else? I k=just followed the install instructions fronm BOP and it was quite easy. I had the engine builder who originally built the 455 do the first install in with the engine still in the car and I thinni he did it with the mains loosened up and the crank dropped down a bit. I did the 400 install myself and it was a snap.


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## novafreak69 (Dec 16, 2012)

I have JUST recently done this! It went extremely smooth... did not even have to remove the crank. Used a vitron seal from Tin Indian. can upload a few pics if wanted...


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## the65gto (Oct 9, 2008)

novafreak69 said:


> I have JUST recently done this! It went extremely smooth... did not even have to remove the crank. Used a vitron seal from Tin Indian. can upload a few pics if wanted...


Yes...pics please. Remove engine?? or raise and take the pan off?? OR?? Comments on how you got the old one out and new one in, any sealant at the joint etc. Since crank still in, did you loosen caps to raise it slightly or?? Tx:eek2:


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## kolnick (Apr 22, 2013)

does a 315/60/15 tire fit in the rear of a 1969 gto on the 15x10 rally two wheels


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## BearGFR (Aug 25, 2008)

You will hear from folks who've successfully re-sealed Pontiacs without having to pull the motor, but you won't hear from a _lot_ of them. The safest way is to pull it. BOP has a new 1-piece seal out now that seems to have a lot going for it. Installation requires you to cut it in one spot in order to fit it around the crank and at first that seems wrong... but when you think about it, if you make the cut then you can be sure that both "sides" are going to mate up with each other perfectly. The crank and seal assembly are then installed into the block with the cut facing up (center of the block portion of the seal groove). This new seal also has two sealing lips, not just one, and the instructions say to fill the valley between the lips with a heavy grease. Everything about this new seal just sounds 'right' to me. Jim has probably built a motor or two by now with this new seal, so if he likes them and gets good feedback on them, then that's what I'll be using in mine whenever I get around to replacing it.

Bear


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## GTO JUDGE (May 14, 2005)

My '70 and a fellow club member's '67 had the seals replaced by jacking the motor up while on an overhead lift. The right tools made it as easy as could be. The motor mounts were removed and engines carefully jacked up. My trans was out of the car at the time being rebuilt so that made the job a lot easier. The '67 I believe had the cross member removed and the tans disconnected. Both mine and his had vitron seals installed and sat untouched on a lift, mine for 2 days and his a week (until our A Team could get back to it) so the sealants would set proper. No leaks from mine after 5 years and his 1 year........ Although I thought mine may have begun when I saw some drops on the floor last mongh but after removing the fly wheel cover and checking the oil pan bolts, all were in need of tightening. After 3 years they needed re-torqued. (We tore the engine apart for inspection and internal cleaning) and repaint etc 3 years ago when I was restoring it and the engine bay. That stopped the drip from that area. 

IMO: Before assuming the RMS is leaking one may want to double check the torque on the oil pan bolts or the oil pan seal itself. Turned out, both mine and his were NOT leaking from the rear main seal, mine was fine with a graphite seal, both mine and his had oil pan gaskets in need of replacing but since the RMS was now exposed, it made sense to replace since it was disturbed. We had similar issues, oil was shooting out the back of the oil pan giving the illusion of a rear main seal leak.


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## goatsnvairs (Sep 12, 2014)

JeffW said:


> The first time I rebuilt my 400, I used the viton seal. I siliconed at the areas specified in the installation instructions, ... result .... leaked like a bad diaper on a baby. The following winter I installed a new forged crank, so naturally, I installed a new viton seal from a different supplier, it was slightly different from the first one I installed. I even made sure the seal mating surfaces were not on the same plane as the bearing cap. The result was the same. IT LEAKS badly. I'm seriously considering trying the graphite rope seal mentioned in a previous posting. I seriously wish you good luck, and if you accomplish a leak free seal, please let me know how you did it.
> 
> THANX
> JeffW


I had the same experience with a Viton seal, followed directions and it leaked bad, real bad. Sounds like this new Graphtite seal is the way to go. I'm doing a teardown this winter and based on all the good press I'm definitely going that way. Glad I looked on tech forum today.


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## detrols (May 24, 2015)

How come I cannot see any pics on this thread. It would be helpful as I am on the same boat with oil dripping from the engine


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## sharecropper (May 9, 2012)

This may be the wrong place for this question but this is my first post and am not computer literate. '70 GTO with 400 engine, automatic trans. Front engine seal blowing oil so bad that other cars are backing away when driving. Do I have to pull the engine to replace the seals, both front and rear?


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## PontiacJim (Dec 29, 2012)

sharecropper said:


> This may be the wrong place for this question but this is my first post and am not computer literate. '70 GTO with 400 engine, automatic trans. Front engine seal blowing oil so bad that other cars are backing away when driving. Do I have to pull the engine to replace the seals, both front and rear?



I am not being evil here, but if you have to ask a question like that I assume you have never worked on an engine. So the first thing I highly suggest is to begin by purchasing a Factory Service Manual for your '70 GTO. The manual will answer your question as well as others.

Front seal can be done with engine in the car. You want to make sure that the snout on the balancer hub is not worn/grooved due to an old hardened seal wearing into it. They do make a repair sleeve that goes over the snout to make it smooth again, so you want to look for this or you may have the same leak with a new seal. You could also go with a new balancer if funds allow - which is a good investment and not too expensive. 

If you are talking about the rear main seal, you would want to pull the engine to make things easier.


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## BearGFR (Aug 25, 2008)

PontiacJim said:


> ..... You want to make sure that the snout on the crank is not worn/grooved due to an old hardened seal wearing into it. .......


Um, isn't the front sealing surface the balancer hub? :grin2:0

Bear


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## PontiacJim (Dec 29, 2012)

BearGFR said:


> Um, isn't the front sealing surface the balancer hub? :grin2:0
> 
> Bear


That was just a test to see if your would catch it. LOL DUH, you are correct. I wrote the response with one foot out the front door going to the mall, so got it wrong. Will edit my post. Thanks for the catch. :wink2: :thumbsup:


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## BearGFR (Aug 25, 2008)

Adding an update to the rear main seal thread.

So, last time I had mine apart I used the new 1-piece seal because I was convinced it was a good idea, it made sense to me, etc. I even published a YouTube video about the process, including some information I got from BOP directly that they, for some reason, don't include with the seal when you buy one.

Long story short: It failed. For two reasons I think, specific to my engine.

Reason 1: My block has been align honed - twice. Once when I built it the first time back in 2009, the second time during my most recent (except for right now) rebuild when I decide to upgrade to main studs instead of bolts. Converting to studs requires this. As a result my main caps have been shaved twice to accomplish the align hone process, and I believe that has resulted in a significant "egg-shaping" of the rear seal groove behind the last main bearing. I know I had to sand quite a bit off the OUTSIDE diameter of the seal to get it to fit right and meet the dimension specs I got from BOP.

Reason 2: My crank (Eagle forged) has the serrations on the surface that contacts the seal, like all the factory cranks did, and I guess they were rougher than I thought they were. When I tore the engine down this time, there was a nice band of _melted_ seal material all around the crank where it was stuck to the serrations.

I still think the seals are good, that it was just a combination of the two above situations that caused mine to fail.

This time, I'm using one of the Best Gasket Co's Graphtite rope seals because I think in my case, it will be more tolerant of whatever "egg-shaping" exists in my seal groove. When I had the rotating assembly balanced for my current build, I had the machinist polish and smooth down the serrations on my crank as well. We'll see how it goes.

Bear


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