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I have a 2004 Suburban 5.3 which has an oil leak that drips on the exhaust header, but cannot see where it is coming from.

Changed valve cover gasket, then had to helicoil all four threaded openings for the valve cover bolts. Oil still leaks. I have a gut feeling it is a cracked head. Can a bad head gasket leak oil on the outer edge of the head and drip on the exhaust manifold?

Pretty bad leak too. When I stop at a red light smoke pours out the divers side of the hood.

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    So I think you are probably right about the head gasket, but I pray its not a cracked head. Also, have you had it on a lift yet?
    – Tristan Crider
    Dec 1, 2019 at 2:05
  • I am praying also.
    – Mike Duke
    Dec 1, 2019 at 3:28

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It would not be the head or the head gasket for two reasons. First, the head gasket sits below the head and the exhaust. There's no way for it to be getting onto the exhaust manifolds. Secondly, there's no pressurized oil which goes through the head. All oil which gets to the top of the head comes through the push rods in the valve train.

I'd suggest either you didn't replace the gaskets on the valve covers correctly, or the cover itself is cracked, allowing the oil to flow through it ... if it is indeed coming from there. You also might not be seeing where the oil is coming from in the first place. It may not be coming from the valve cover or valve cover gasket at all, but some other place. You might want to thoroughly clean the area so you can find the leak. To do that, you might get some fluorescent dye, which you can track with a UV light. It can help you pinpoint exactly where the oil is coming from.

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  • Thanks for the reply. I haven't had on a lift yet and I did think about not fitting the valve cover gasket on correctly. That will be my next move. To clean the area and remove the valve cover and inspect. When I first replaced the valve cover o ring and went to tighten the 4 bolts all but one was stripped. So helix coiled all 4 and the cover did snug down tight. Also when it leaks, I do not see it coming from the gasket area. Will do a cover removal again and double check. Not a very laborious job on the 5.3. Will let you know what the results are tommow. Thank you again. Mike
    – Mike Duke
    Dec 1, 2019 at 3:15
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    I think it's suspicious that at least one of the existing holes were stripped. For me that indicates that a previous owner or mechanic attempted to resolve a leak with tightening. Check the valve cover for warpage or other damage, check the surface of the head where it mates with the gasket for surface irregularities or other defects or damage.
    – jwh20
    Dec 1, 2019 at 20:20
  • My experience is that the valve cover bolts do not need to be very tight. Did you use a torque wrench? Not familiar with that motor, but most service manuals have torque specs and tightening order for valve covers to avoid leaks. You might want to check into that. Also, since the bolts were stripped, it's possible that the valve cover itself is bent.
    – David Watson
    Dec 3, 2019 at 17:41

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