Rear main seal on a 78/79 model 258 - Off-Road Forums & Discussion Groups
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post #1 of (permalink) Old 01-24-2005, 03:49 PM Thread Starter
 
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Rear main seal on a 78/79 model 258

Hey guys... I've got a '78 or '79 model 258 short block in my '87 YJ, and the rear main seal is leaking. My Haynes manual is for the Wrangler, so I don't have a reference for replacing the rear main seal on that block. Can you guys tell me if that is a 1 or 2 piece seal? Can I replace it by dropping the pan? What is the recommended plan of attack?
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post #2 of (permalink) Old 01-24-2005, 04:12 PM
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Re: Rear main seal on a 78/79 model 258

2 pice,

Buy two seals....

You'll likely do it twice..

Hint: Loosen the crankshaft cap bolts to drop down the crankshaft.. don't forget to retorque when done.

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post #3 of (permalink) Old 01-24-2005, 07:45 PM
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Re: Rear main seal on a 78/79 model 258

Don't let it intimadate you....it's actually easier than it looks. Do as Leve says, loosen the crankshaft caps...you won't be able to see it drop....but, it will help a little (the tranny is holding up the rear end).
To get out the top gasket, take a flat punch and give one end of the top seal a tap. It should push the seal out (actually, it rotates it out). New one slides right in....make sure you use plenty of oil on it.
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post #4 of (permalink) Old 01-25-2005, 12:53 PM Thread Starter
 
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Re: Rear main seal on a 78/79 model 258

Thanks for the links (awesome resource, BTW!) and words of encouragement. I've heard that a lot of shops won't even touch the job between having to re-do it sometimes and the opportunity to screw up a bearing. I have to admit... the thought of an upper bearing half falling out of position and then not getting properly reseated makes my personals pucker. [img]images/graemlins/blush.gif[/img] But I think I'm gonna give it a whirl anyway.

Any advice particular to preventing the hosing of a bearing?

Thanks.
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post #5 of (permalink) Old 01-25-2005, 02:02 PM
 
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Re: Rear main seal on a 78/79 model 258

Not to sound stoopit -
But please triple check to make absolutely sure it is not the back of the valve cover leaking, before you condemn the rear main seal.

I have seen several replaced only to find it was actually the valve cover. And the misdiagnosis covered up as a "comeback".

If it really is the rear main - you have been given good advice above. Have at it. Take your time, work clean, and you will be fine.
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post #6 of (permalink) Old 01-25-2005, 09:27 PM
 
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Re: Rear main seal on a 78/79 model 258

Don't forget to have a look at the oil pressure sending unit after you check the valve cover, seen many rear main seals replaced because of them on various vehicles too.
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