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Trick to prevent V6 rear main from leaking

Posted: Tue Jul 31, 2007 7:33 am
by AlfaBeta
Hi gang,

I have an idea to prevent the rear crank main from leaking oil past the cigarette seals. See what you guys think: I'm in the middle of doing a full engine rebuild and I noticed on both sides of the rear main crank cap there is about a 1mm or so gap between the cap and the block wall. The cigarette seals are in the middle of this gap (in other words if you stuck a feeler gauge into this gap you would contact the rubber cigarette seal.
Is this gap there for a reason? To allow for expansion when warm? I thought of squirting a thin bead of permatex form-a-gasket into the gap to seal it even better. This sealant (# 1372) cures soft and is resistant to oil. I wanted to get some opinions first before I went ahead and did this.

thanks
AlfaBeta

Posted: Tue Jul 31, 2007 8:00 am
by x-rad
I reused the old cig seals and just put a small amount of permatex high temp in the hole and on the cig seal sides before driving in the cig seal.

it squished out of all the little gaps, which then was cleaned up.

No leaks yet and it's been two years

Posted: Wed Aug 01, 2007 7:58 am
by AlfaBeta
Hi x-rad. What if the seals are already put in place and rear main torqued down. Could I just squirt the sealant into the gap alongside the main?

Posted: Wed Aug 01, 2007 8:21 am
by Barry
Dont use the seals AT ALL..

Bolt down the cap and torque.

Use gray Loctite silicon sealer and sqush it into the top opening UNTIL IT STARTS SEEPING OUT OF THE JOIN LINE CLOSE THE PARTING LINE.

No more leaks EVER.!

Posted: Wed Aug 01, 2007 11:45 am
by x-rad
I would definately use some type of sealant the way I described or what Barry says.....but you can't get it in there with the cap torqued...

When i reused the old cigs, i had to kinda slide the cap and the cigs down together

the old cigs had little fingers of sealant stuck to them which I trimmed off as the new sealant was going to fill up the sapce. Also, this made them easier to slide in..

the cigs are old and dried and only a little flexable and act like space fillers....so new permatex around any gaps is very helpful.

Just keep any sealant away from bearing and crank and clean up any extra on the crankcase side