73-87chevytrucks.com
73-87 Chevy _ GMC Trucks => Engine/Drivetrain => Topic started by: Harmon on November 12, 2012, 07:56:01 pm
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I have a 86 chevy c-10 1/2 ton pick up and am about to have to take the Carb off to rebuild it. I have noticed a few spots of oil around the bolts on the intake. the oil will sit in the valley around the head of the bolt that holds the intake to the head.
My question is if the oil is coming up the bolt? If so should I put thread sealent on the bolt threads and retorque? OR should I pull the entire intake, and put new gaskets?
I guess I am just not sure what I should do.
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Although oil bleeding up around the intake bolts is common, are you sure your valve cover gaskets aren't leaking? Do you see any blow-by puffing out of the valve cover with the engine running when you remove the oil fill cap?
As far as the intake gaskets are concerned, how do the spark plugs look in cylinders 4, 6 and 8? Any deposits shrouding the insulators and/or ground electrodes? If so, replace the intake gaskets (and the spark plugs). If not, wire wheel the bolt threads and try applying a little #2 Permatex or liquid Teflon sealer on the bolts, one-at-a-time.
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I've got to hand it to you - your engine is REALLY CLEAN!! :)
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Thanks! when I got this truck a few years ago, I took the hood, front fenders, grill off, and cleaned/painted it all up. Plus painted the block Chevy orange....
I do believe the valve covers are leaking. The 4 bolts that hold the valve covers on seem not enough to me. I have two Oldsmobiles, and they have like 8 or 16 bolts...(cant exatcly remember) BUT they totally keep the pressure more equal on the VC gasket.
Thanks for your help.
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Unfortunately, SB valve covers have a propensity for leakage even with the added steel reinforcements you have. You can gently reshape and straighten distorted valve cover flanges and replace the gaskets to temporarily stop/slow the leaks, but oil leaks will eventually return in 18 to 36 months, especially in the vicinity of the EGR valve and exhaust-side gasket rails, because of the concentration of heat in those areas. Even silicone will break down from the heat. Stout, cast aluminum covers may extend the service intervals, but won't eliminate leakage completely. Periodic replacement of the valve cover gaskets on a SBC is simply routine maintenance. I hope some of this information helps you get a handle on resolving those pesky oil leaks.
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How tight are you torquing the bolts to the valve cover? I just cinch them down to touch and then add a 1/4-1/2 turn. If you crush them down they will leak. Are you using cork or rubber gaskets?
Are you siliconing the gasket to the head or valve cover or both? I had good luck with just siliconing it to the valve cover and leaving the head dry.
You may also want to inspect the head surface for uniform straightness.
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I used cork valve cover gaskets. I took them off tonight and they have an indention in them big time from being tightened. I did it really easy at first, but over the past few years I have had to retighten them
I went ahead and pulled the carb, and ac components so that I could pull the intake off easily. I know I have to pull the distributor...any other advice for me before I tackle this tomorrow?