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73-87 Chevy _ GMC Trucks => Engine/Drivetrain => Topic started by: sbx22 on March 20, 2012, 05:41:50 pm

Title: Rear main bearing cap question. Is this right?
Post by: sbx22 on March 20, 2012, 05:41:50 pm
Long story short, developed an oil leak between tran/engine which I believe was coming from rear main. No other obvious leaks which I had checked already. BTW, 350 SBC crate motor I picked up from TuffDawg through Arizona. It only has 300 miles.

Ok, so I think I got all the tough tasks out of the way. I'm taking a halftime break right now, maybe until tomorrow. Anyway, snapped a couple pictures of the rear main seal as well as cap. Take a look at it yourself. There are two gouges onto the cap. I DID NOT DO THIS. I found it this way and how it is installed, there was no way I could have used a screw driver to get at it through that angle. I need to replace the cap right?
(http://i462.photobucket.com/albums/qq344/sbx22/IMG_7922.jpg)
(http://i462.photobucket.com/albums/qq344/sbx22/IMG_7921.jpg)
(http://i462.photobucket.com/albums/qq344/sbx22/IMG_7920.jpg)

Also, if you take a closer look at the seals, it appears that the builder used some sort of sealant along the ridge of the seal. It made it a PITA to get the top seal off. I almost cried. From what I read, you're not supposed to use any sort of sealant along the ridge, am I correct? I do not ever want to do this again.
(http://i462.photobucket.com/albums/qq344/sbx22/IMG_7915.jpg)
(http://i462.photobucket.com/albums/qq344/sbx22/IMG_7913.jpg)
Title: Re: Rear main bearing cap question. Is this right?
Post by: jaredts on March 20, 2012, 07:41:53 pm
Rear main leaking after 300 miles, yikes.  If you're talking about the lines in the bearing I'm pretty sure they're lubrication grooves and you're fine.  I don't know about sealant being prohibited on the seal itself.  I wouldn't think it would be a problem during a rebuild, but you wouldn't want to with the crank in place.  Have you called TuffDawg?
Title: Re: Rear main bearing cap question. Is this right?
Post by: sbx22 on March 20, 2012, 08:01:34 pm
I have never seen these grooves used before. I wonder if this is attributing to the leak? Can anyone else chime in?
Title: Re: Rear main bearing cap question. Is this right?
Post by: VileZambonie on March 20, 2012, 08:33:17 pm
That looks like they took a die grinder to the bearing. Replace the seal, make sure the lip is positioned correctly and I always slightly offset the seal. I would replace that bearing as well. A small amount of rtv at the rear bearing cap to block and correctly positioned pan gasket will help prevent leaks.
Title: Re: Rear main bearing cap question. Is this right?
Post by: Lt.Del on March 20, 2012, 09:27:29 pm
I got my engine from Tuff Dawg in Phoenix.  Send Darl, the engine builder, those pics.  That isn't right.  Pics below are from my Tuff Dawg 383 stroker i bought 7 years ago.  I had a rear main leak and fixed it in a matter of an hour or two.  Note the seal and groove. My bearings did not look like that, that's why i say send those pics to Darl's email.  I have his email if you message me i can give it to you. 



(http://www.delbridge.net/seal3.JPG)


(http://www.delbridge.net/seal4.jpg)

(http://www.delbridge.net/seal5.JPG)

(http://www.delbridge.net/seal6.JPG)
Title: Re: Rear main bearing cap question. Is this right?
Post by: HAULIN IT on March 20, 2012, 10:22:29 pm
Definitely someone took a wiz wheel with some care & a plan & grooved that. I've not seen anything like that, but the person who built it surely has a theory...good, bad or otherwise. Honestly, I've never seen the back bearing itself be a problem (without the others junked from trash or something). The goo on the seal wouldn't have bothered me if it wasn't leaking  ;) Lorne   
Title: Re: Rear main bearing cap question. Is this right?
Post by: VileZambonie on March 21, 2012, 12:58:05 pm
Maybe the builder was trying to direct oil away from the rear main seal so it wouldn't leak lol  :D I am curious what his "theory" is too