Author Topic: mystery oil leak  (Read 522 times)

RAS68

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mystery oil leak
« on: November 05, 2018, 12:23:32 AM »
I need help with a real mystery. I have an engine oil leak under the hood apparently from the passenger side valve cover bolt holes. My car is 1968 SS 396 with automatic. The engine is stock with stock heads and intake manifold and carb and original valve covers ( I think , they may be very good repros). Every time I drive the car now there is engine oil on the valve cover between the hold down bolts ( on the lip toward the intake manifold side). There is no oil under the valve cover lip on the intake manifold just on the chrome lip between the bolts. I have tried re-tightening them and even putting thin rubber gaskets around them. Still I get the oil between the valve cover bolts. Sometimes when I drive the car for 10 or 15 miles or more there will be a light spray of engine oil on the underside of the hood right over the passenger side valve cover. There is no evidence of engine oil on any other parts anywhere under the hood. No oil on the underside of the air cleaner or on the flat area of the valve cover or on the rest of the engine. No evidence of oil around the air breather tube that I can find. the engine oil is on just the underhood area over the passenger side valve cover and on the passenger side valve cover lip that is on the intake side. This is driving me crazy so I hope the FORUM can help me out with some ideas. Thanks in advance.
Allen
'68 SS L34 07C NOR

Kelley W King

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Re: mystery oil leak
« Reply #1 on: November 05, 2018, 01:23:17 PM »
Sounds like blowby to me. I guess you have the tube to the air cleaner? Might be spraying by the rubber grommet and dripping back. If it is it would be hard to see with the engine fan blowing. Most of my cars get a trace of oil in that area after be run awhile. At shows my first thing is paper towel that area. A clogged PCV could make it worse.
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william

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Re: mystery oil leak
« Reply #2 on: November 05, 2018, 04:14:56 PM »
Factory BB w/chrome covers used special gaskets coated with a silver sealant. Paragon has them.

https://www.paragoncorvette.com/p-352465-valve-cover-gasket.aspx



RAS68

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Re: mystery oil leak
« Reply #3 on: November 05, 2018, 04:30:34 PM »
Thanks guys for the prompt reply's and the potential fixes. I will double check the breather tube grommet area and order the paragon gaskets. Any other ideas from FORUM readers?

Allen
'68 SS L34 07C NOR

Kelley W King

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Re: mystery oil leak
« Reply #4 on: November 07, 2018, 01:13:54 PM »
If you want to check for blowby take the fan belt off and run it a short time and watch. The fan can blow the mist and you will not see it. A defective PCV valve or hose will make it worse.
69 Z28 RS Scuncio Hi Performance
69 SS L78
67 SS Chevelle
64 Corvette
66 GTO Tiger Gold
77 Trans Am Special Edition

rodent

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Re: mystery oil leak
« Reply #5 on: November 07, 2018, 05:49:36 PM »
Are the intake bolts that thread into the valve area sealed?

From the front of the engine:

Drivers side: 1st, 5th, 7th
Pass side: 2nd, 4th, 8th

All of these bolts are open into the inside of the engine, and if not sealed oil will creep through them.

Kelley W King

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Re: mystery oil leak
« Reply #6 on: November 07, 2018, 09:20:13 PM »
good call Rodent. It is one or the other. Intake bolt sounds likely.
69 Z28 RS Scuncio Hi Performance
69 SS L78
67 SS Chevelle
64 Corvette
66 GTO Tiger Gold
77 Trans Am Special Edition

rodent

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Re: mystery oil leak
« Reply #7 on: November 27, 2018, 08:08:25 AM »
What transpired?