LT1-LT4 Modifications 1993-97 Gen II Small Block V8

rear main replacement difficulty?

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Old Jan 11, 2012 | 09:33 AM
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Default rear main replacement difficulty?

so i have a major oil leak somewhere on the backside of the engine and im thinking rear main but what else is in the area that could be causing a pretty big leak? how difficult is it to replace the rear main? i looked under the car yesterday while at idle and every minute or so like 3-4 consecutive drops of oil drip down but when car is turned off it does not leak as bad but i need to get this problem fixed. leak started after car was given full seafoam treatment and oil changed to mobil 1 synthetic
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Old Jan 11, 2012 | 09:37 AM
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From: Jackstandican
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More than likely it is the back of the intake and not the rear main. Start from the top of the back of the engine feeling around the intake/block surface to see if there is any residue. Feel around the valve covers as well.
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Old Jan 11, 2012 | 09:40 AM
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i hope its not the back of the intake as i just replace intake manifold gaskets like 2 or 3 weeks ago but i will check. it could be the passanger side vc i have noticed oil around it but didnt think it would be enough to cause this bad of a leak
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Old Jan 11, 2012 | 09:47 AM
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From: Jackstandican
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If it is indeed the rear main then you'd also have oily residue w/in the bellhousing. Take the inspection cover off and check.
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Old Jan 11, 2012 | 10:01 AM
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when i replaced the oil level sensor housing the other day i looked all over to try and find where the oil was coming from but honestly theres oil residue all over the place that is making it hard to pinpoint where its coming from but i will be checking back of intake, valve covers and ill take the inspection cover off.

SSRRR thanks for all your help btw i think you have posted in just about every one of my threads and even though i hate seeing "man-crush warning" with the pink letters after all your posts, i appreciate all the help
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Old Jan 11, 2012 | 10:27 AM
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From: Jackstandican
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Before removing/checking anything you can also clean the engine thoroughly using something like Simple Green. Drive around for a good 10 minutes with oil at operating temperature and then check all suspected places. Like stated, check from the top down. Thanks for the kind words.
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Old Jan 11, 2012 | 11:05 AM
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That's the plan and thinking back im questioning weather the back of the intake got torqued down enough cause iirc it was tough to get to those backside bolts
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Old Jan 11, 2012 | 11:10 AM
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I will bet its the intake , If you dont use good sylicone to seal it they will leak as bad as you mention mine did . I stopped mine by using permatex sylicone that stuff is awsome alittle more pricey but it better then chasing oil leaks and pulling the intake .
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Old Jan 11, 2012 | 11:54 AM
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Rear main isn't real difficult. Time consuming. Not difficult. But check everything before you start crawling around under a car and bench pressing transmissions. Buddy of mine thought he had a rear main leak on his ls1. We took everything apart and put it back together just to find out that wasn't the cause. He didn't even check, he just assumed. Doesn't work out so great.
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Old Jan 11, 2012 | 12:22 PM
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Thanks for answering my question Mississippi and by no means was the rear main first on the list of things to check just wanted to know how difficult it was just in case I have to get in there and replace it but the rear main was replaced when I had the clutch put in about a year ago
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Old Jan 11, 2012 | 01:08 PM
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Just like ocala, i fixed my intake leak. mine was leaking in the front which made it lots easier. First thing ya gotta do is clean off the oily residue with a good cleaner or the silicone will not stick. after cleaning it, spray it down real good with carb or brake cleaner and let it dry, then apply silicone.
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Old Jan 11, 2012 | 04:29 PM
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Way back, I had an oil leak and it looked just like it was coming from the rear main, but in actuality it was coming from the rear of the intake. with the wind and leak, the oil proceeded down toward the back of the engine looking like a rear main. I washed the back of the intake, made sure there was no oil and after a short time, there was oil back there. Also make sure it is not your oil sending unit...I had that happen too..
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Old Jan 11, 2012 | 07:17 PM
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As mentioned above, check the problem areas. If it is the rms, dropping the trans will be the most time consuming.GL
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Old Jan 11, 2012 | 08:55 PM
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Thanks for all the info guys. I won't be able to look at it till Friday cause I'm off work then but I'll make sure to post what I find
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Old Jan 11, 2012 | 09:08 PM
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get a few cans of brake clean. it helps to narrow down leaks much faster. its tough to narrow down those hard to reach/ impossible to see places. makes a $10 sight mirror from sears worth its weight in gold
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