What is a "Split" Rear Main Seal? Pic will Answer...
Thread Starter
Team Owner
Joined: Aug 1999
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From: Ontario
What is a "Split" Rear Main Seal? Pic will Answer...
That question. The topic of a rear crankshaft main seal comes up from time-to-time as they are prone to leakage. And mine is gone so I picked up one today. It occurred to me that sometimes we who have been through the drill get caught up in rhetoric (e.g. the word split) when C3 veterans get into some discussions. I thought back about 10 years and realized that at that time, I did not know a split seal from an exhaust donut.
So for readers who do not know what a "split" seal is, here is one. Basically it is a seal that can be installed without dropping the transmission to get a "whole" seal unto the crankshaft. The oil pan does have to be dropped and the rear main bearing cap removed, but it is generally a fairly simple install. The Mitchell flat rate on this repair is 3.1 hours. I did not check but I suspect that having to drop the transmission would add about 4-5 hours of labour. So the C3 has an advantage over later Corvettes in this respect. I leave it to more technically competent members to add comments if they wish.
So for readers who do not know what a "split" seal is, here is one. Basically it is a seal that can be installed without dropping the transmission to get a "whole" seal unto the crankshaft. The oil pan does have to be dropped and the rear main bearing cap removed, but it is generally a fairly simple install. The Mitchell flat rate on this repair is 3.1 hours. I did not check but I suspect that having to drop the transmission would add about 4-5 hours of labour. So the C3 has an advantage over later Corvettes in this respect. I leave it to more technically competent members to add comments if they wish.
Le Mans Master
Joined: Apr 2000
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From: cincinnati ohio
St. Jude Donor '09
Re: What is a "Split" Rear Main Seal? Pic will Answer... (paul79)
All early smallblocks use a two piece main seal. It has nothing to do with ease of installation. The flange on the early cranks are such that it would be impossible to do it anty other way.
You probably have heard the terms "two piece and "one piece" rear main seals... they are not interchangable one for early style cranks the other for late :cheers:
You probably have heard the terms "two piece and "one piece" rear main seals... they are not interchangable one for early style cranks the other for late :cheers:
Race Director
Joined: Dec 1999
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Re: What is a "Split" Rear Main Seal? Pic will Answer... (yellow 72)
When you install it rotate it so that the parting lines don't meet up w/ the parting line between block & cap. Use a bit of aviation sealer on the sides where the 2 halves meet. This way you'll have a good leak free seal.
Marck
Marck
Race Director
Joined: Dec 1999
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Likes: 9
Re: What is a "Split" Rear Main Seal? Pic will Answer... (paul79)
It's from permatex (loctite), I forgot the part no. BUT silicone should work just fine.
One thing, was there an installation tool in the package, something like a small shoehorn or does the seal not have sealer on the backside (small raised beads on the back)
If it has, you need some sort of shoehorn like installation tool to prevent scraping off the sealer. If it hasn't put some sillicone on the back too (VERY LITTLE) or it'll still leak.
Marck
[Modified by Twinnie, 3:35 AM 6/26/2002]
One thing, was there an installation tool in the package, something like a small shoehorn or does the seal not have sealer on the backside (small raised beads on the back)
If it has, you need some sort of shoehorn like installation tool to prevent scraping off the sealer. If it hasn't put some sillicone on the back too (VERY LITTLE) or it'll still leak.
Marck
[Modified by Twinnie, 3:35 AM 6/26/2002]
Le Mans Master
Joined: Oct 2001
Posts: 5,943
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From: Wildwood IL
Re: What is a "Split" Rear Main Seal? Pic will Answer... (paul79)
Twinnie,
What is aviation seal?
What is aviation seal?
Eddie
Thread Starter
Team Owner
Joined: Aug 1999
Posts: 30,995
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From: Ontario
Re: What is a "Split" Rear Main Seal? Pic will Answer... (Twinnie)
Twinnie,
This is the installation "tool." A small piece of plastic?? GM must know what it is doing....There are no raised beads on the seal itself.
This is the installation "tool." A small piece of plastic?? GM must know what it is doing....There are no raised beads on the seal itself.
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Thread Starter
Team Owner
Joined: Aug 1999
Posts: 30,995
Likes: 99
From: Ontario
Re: What is a "Split" Rear Main Seal? Pic will Answer... (Twinnie)
For what its worth, here is part of the GM instructions. Large file so people can read.
http://temp.corvetteforum.net/c3/pau...srtuct_002.jpg
http://temp.corvetteforum.net/c3/pau...srtuct_002.jpg
Le Mans Master
Joined: Apr 2000
Posts: 5,202
Likes: 10
From: cincinnati ohio
St. Jude Donor '09
Re: What is a "Split" Rear Main Seal? Pic will Answer... (paul79)
The little plastic tool is to keep the sharp edge on the block from shaving off part of the seal as you feed it into place. As Twinnie explained, when you install it don't make it flush with the block so the parting lines on the seal and the main cap/block are in different spots :cheers:
