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how install rear main seal on 1965 6 cylinder engine

 
scutdude
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Posts: 62
Joined: 09/07
Posted: 03/25/08 05:26 PM

Is it possible to install the rear main seal with the engine installed?  

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mechanicalguy48
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Posts: 854
Joined: 12/07
Posted: 03/25/08 06:18 PM

Yeah it is possible even though the shop manual will say it isnt. It is extremely hard though and unless you have a lot of patience and time ,,,just replace the lower seal. The lower seal will just come off with the rear main cap and its fairly easy to replace, you might solve your problem with that. All you have to do is take off is the pan for that. The top seal is pinned in place and requires that in order to remove it you must drop the crank enough to get clearance to clear this pin in the upper seal groove and pull the seal around the lowered crank to remove it. In order to drop the crank you have to remove all the main bearings and pull the trans(and flywheel and or flex plate) back so that the crank will drop a half inch or so. Then you have to work on the seal in order to free it,,,and remember its pressed in there pretty good. Then even when you get it out you have to work the new seal up into this channel and get it flush with both sides ,,,its a difficult job and almost easier to remove the engine and do it. Its one of those things thats possible but no one wants to do it that way. Seal fit is critical too and even with the engine out it requires some experience to get them in properly, cut and sealed. So I guess the answer is ,,yeah but!!In older engines they used to pull the seals around without dropping the crank using a tool that would latch on to one end of the seal, but when the pin is in there it makes it nearly impossible to do that and keep the seal intact. There might be a few guys who will tell you they did it,,,, but I think those guys have oil on their garage floors. Newer engines now use a one piece seal thats much better.  

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mjb1032
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Posts: 181
Joined: 12/07
Posted: 03/27/08 01:39 PM

Mechanical Guy,
 Would your answer also apply to a 68 289?  I am going to be removing the engine, and I would like to replace the seals and gaskets, but if it's that much of a pain- maybe I'll just change the lower 1/2 (of the rear main)as you stated.
I also want to install new freeze plugs.  The existing ones are pretty rusty, and for peace of mind I'll put in new ones.  Would you recommend brass ones?, Or stick with the steel?  
 The engine only has roughly 3K on it since it's last rebuild in 1998, but it appears to be seaping oil from a few places.  This way I can also give it some new paint.
Any recommendations of things to do while it's out are appreciated.
Thanks, MB.  

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scutdude
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Posts: 62
Joined: 09/07
Posted: 03/27/08 07:33 PM

Are you sure it is pinned?  That sounds like a real problem.  Any one else have any experience doing this?  

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mechanicalguy48
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Posts: 854
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Posted: 03/28/08 04:30 PM

The answer is the same for the 289. The pins are put in by the factory to keep the seals from rotating, which if you think about it ,,,, would sure be a problem. The pin is in the groove and the seals settle over it when they are installed.
I have never experienced problems with standard freeze plugs, but brass is less liable to corrode and softer so it seals better generally and I would use it in a core that had a history of leakage. When you have the engine out is the time to replace those gaskets and seals its a much easier job.  

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mjb1032
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Posts: 181
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Posted: 03/29/08 02:30 AM

Thanks MechGuy  

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scutdude
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Joined: 09/07
Posted: 04/10/08 05:16 PM

What about using an engine oil stop leak additive?  

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mechanicalguy48
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Posted: 04/10/08 05:34 PM

With all due respect to oil additives,,,, I have never seen one seal up an oil leak in an engine in 40 years of working on them. I will say one thing ,,, they are a lot simpler to do, but alas no short cuts Scutdude.  

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scutdude
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Posts: 62
Joined: 09/07
Posted: 05/28/08 12:48 PM

Finally got around to replacing the seal.  Yes, I had an original Rope seal in place.  The lower seal was easily replaced and note that it was pinned as well.  I did not replace the upper seal and will cross my fingers my problem is fixed.  

If not, I will have to pull the engine, flip it upside down, and remove the crank shaft to replace the upper seal.  

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