Barracuda Challenger Forum

Author Topic: BB rear main seal help  (Read 1518 times)

Offline NoMope Greg

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BB rear main seal help
« on: October 06, 2008 - 04:41:21 PM »
I (finally) started building my engine today.  This is my first engine I've built from scratch, so I'm taking it slow and careful.  I've run into my first problem - I'm not sure which way I'm supposed to orient the rear main seal.  Five references (the package, the Internet and three books) either say nothing or are unclear.  The Fel-Pro package says to have the word "Outside" facing out, but then conveniently leaves the word off the seal!  :swear:  How To Rebuild Big Block Mopar Engines says to have the edge with the greater bevel facing in, but I'm not 100% sure which side is "more" beveled.  I'm 90% sure it's the side I've labeled "beveled" below and the side labeled "Flat" faces out.  But that last 10% is going to bug me - plus, if I get it wrong, I end up with a major leak, so I think it's better to check first.  :1zhelp:
Greg
2003 Ford Escape XLS
Currently Mopar-less :(

Cuda-Challenger.com

BB rear main seal help
« on: October 06, 2008 - 04:41:21 PM »



Offline Moparal

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Re: BB rear main seal help
« Reply #1 on: October 06, 2008 - 05:46:03 PM »
Looking at an oil seal and useing common sense would dictate the installation. The pressure is inside the engine so as pressure builds up it seats the seal more onto the crankshaft. The open lip goes to the inside. So if wind pressure pushes on the seal the lip pushes up and seal even tighter. If it is backwards then it will leak through when you have ring blow by.    <  the open faces in towards the engine  so when air forces push on it  ---> >it pushes it tighter

I hope I could say it clear enough for you

Offline NoMope Greg

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Re: BB rear main seal help
« Reply #2 on: October 06, 2008 - 05:59:12 PM »
Umm...no.  I appreciate the design lesson and all, but I'm still not 100% sure which end faces in.  I have to assume that by "open" end, you mean the beveled edge, but I'm checking with the experts here because I don't want to assume, I want to do it right the first time.  All I need to know is: Which way faces in?  Beveled edge or flat edge?
Greg
2003 Ford Escape XLS
Currently Mopar-less :(

Offline hemiken

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Re: BB rear main seal help
« Reply #3 on: October 06, 2008 - 06:03:40 PM »
Hey Greg, what Alan was saying is right.  But simply put the pointy edge inwards, there is a shovel shape edge that pushes against the crank. :2thumbs:
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Offline Moparal

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Re: BB rear main seal help
« Reply #4 on: October 06, 2008 - 06:10:11 PM »
open end in :2thumbs:  And use some sealer on the outer side  where it sets in the sadled, then where it meets together in a full circle. When you install the seal container to the block, you will have 2 paper strips , if its a bb. Soak these in oil pryor to installing them. Have a dab of sealer on the bottom end of the block where the tabs stop.   Never ever any leaks. Don't over tighten the 12 point , long bolts either. Pull them down even and tight. Dab some sealler on the cornewr edges.   You can do it

Offline NoMope Greg

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Re: BB rear main seal help
« Reply #5 on: October 06, 2008 - 06:15:36 PM »
Thanks, guys, I'll give it a shot.  And I only have one piece of paper and it's not immediately obvious where that goes.  I'll look at it again.  I just want to get set up with this before I get all goobered up with assembly lube for the bearings and set the crank in.
Greg
2003 Ford Escape XLS
Currently Mopar-less :(

Offline 73EStroker

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Re: BB rear main seal help
« Reply #6 on: October 06, 2008 - 10:08:10 PM »
Also another trick is to stagger the seal half joints so that one side is 1/2" down and the corresponding piece sticks out 1/2". that way the seal joint is not in the same plane as where the metal seal holder joins.
Barry (Salmon Arm)

Offline moper

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Re: BB rear main seal help
« Reply #7 on: October 08, 2008 - 09:29:12 AM »
Like was said... the lip...this is the sharpest thinnest part of the rubber (I beleive in your pics that is facing your palm as opposed to away)  the lip always faces the oil.

Offline Chryco Psycho

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Re: BB rear main seal help
« Reply #8 on: October 08, 2008 - 07:08:18 PM »
it shoudl sit like this

 //
[ ] pointed > into the engine

Offline NoMope Greg

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Re: BB rear main seal help
« Reply #9 on: October 09, 2008 - 01:59:56 PM »
Thanks for the reply guys.  That's why I asked - because the simple things aren't so simple when it's the first time you've done it. 
Greg
2003 Ford Escape XLS
Currently Mopar-less :(

Cuda-Challenger.com

Re: BB rear main seal help
« Reply #9 on: October 09, 2008 - 01:59:56 PM »