L48 engine tear down
Thread Starter
Burning Brakes
Joined: Apr 2009
Posts: 807
Likes: 2
From: VIRGINIA BEACH VIRGINIA
L48 engine tear down
I have a small oil leak from the head on the passenger side below the rear spark plug. Engine still runs good so I think i am going to pull the heads, and take them up to the machine shop and see if they can rebuild the heads and clean them up. What else should I do while I am in the engine. I am not very engine smart so I do not want to get to involved in it. It is a stock 350 with an eldebrock intake holley 600, headers going back to dual exhaust. The guy I bought it from said he put a racing cam in it but other than that, I don't know anything about the pistons or cams. Looking for opinions and options. I also have a 3 speed auto with a shift kit (not sure what kind). Thanks for the ideas.
Team Owner
Joined: Jan 2006
Posts: 37,637
Likes: 3,118
From: Crossville TN
Are you sure that your leak is from the head and not from a valve cover/gasket? An oil leak from a cylinder head is pretty rare unless it is from a porous area that opens to a drain-back hole or a head that develops a crack in it. Clean the area of the leak off well with a solvent so that it is free of oil/grease and dry. Run it for a few minutes and check it again. I'm betting on a valve cover gasket leak.... 
Burning Brakes
Joined: Sep 2009
Posts: 1,124
Likes: 140
From: Western New York
I'll go along with that! I had the same leak on the pass. side on my '72 350. At first I thought it was the valve cover gasket so I replaced that. Leak continued. Removed my Edelbrock Performer manifold and replaced the intake gasket set with new felpro gaskets. Used RTV on front and back of intake instead of the rubber S gaskets and the leak is gone and my garage floor is clean again. Good luck!
Thread Starter
Burning Brakes
Joined: Apr 2009
Posts: 807
Likes: 2
From: VIRGINIA BEACH VIRGINIA
I will try this. This sounds alot easier than taking the heads off. Duane, you didn't use the s gasket at all? I guess I could try that. I may try changing the valve springs and seals while I am at it and in the engine. Got any pointers on that? I will skip pulling the heads. Thanks again.
Melting Slicks
Joined: Apr 2006
Posts: 2,084
Likes: 14
From: Airdrie Alberta
Edelbrock say not to use the end gaskets...just rtv
http://www.edelbrock.com/automotive_.../2000/2101.pdf
http://www.edelbrock.com/automotive_.../2000/2101.pdf
Race Director
Joined: Apr 2000
Posts: 17,676
Likes: 201
From: Who says "Nothing is impossible" ? I've been doing nothing for years.
Invest 20 bucks in an oil leak detection kit, once you have one you will wonder why you never had one before, an oil drip under the oil drain plug could be coming from the back of the valve covers or anywhere else, the oil goes to the lowest point, you will be amazed at where it is actually coming from, very rarely where you think 
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Thread Starter
Burning Brakes
Joined: Apr 2009
Posts: 807
Likes: 2
From: VIRGINIA BEACH VIRGINIA
I am going to go with the above advice and stick with the intake and valve cover gaskets. If that doesn't work, then the heads will come off with some help from here.
Le Mans Master
Joined: Oct 2006
Posts: 7,123
Likes: 433
From: Gladstone MO
C3 of Year Finalist (appearance mods) 2019
When you get the intake off and everything cleaned up, wipe EVERYTHING down with alcohol, then install the side gaskets for the intake with a small bead of 3M 8001 around the water jackets, then a fat bead of RTV across the ends.
Using alcohol removes all traces of oil- RTV will not stick to anything that has even a small trace of oil on it.
Using alcohol removes all traces of oil- RTV will not stick to anything that has even a small trace of oil on it.
Advanced
Joined: Jul 2009
Posts: 59
Likes: 0
A couple of things here. I'd replace the valve cover gaskets first, then look again after driving the car a while for leaks- after cleaning off the oil at the suspected spot. Don't forget to make sure where the hold down bolts go thru the covers to tap down that area to make a flat surface across where the gasket will go. That is a notorious spot where overtightened bolts bend the valve cover.
If you can do it, you can clean the area where the intake meets the cylinder head with carburetor cleaner or contact cleaner (used in electronics and available at Home Depot) and then apply by finger some rtv silicone to get a temporary seal. If it holds, then you'll know that that's where your leak is. I'd make an extra effort here to aviod removing the intake.
If you can do it, you can clean the area where the intake meets the cylinder head with carburetor cleaner or contact cleaner (used in electronics and available at Home Depot) and then apply by finger some rtv silicone to get a temporary seal. If it holds, then you'll know that that's where your leak is. I'd make an extra effort here to aviod removing the intake.
