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Hugh R's Avatar
 
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Unhappy Valve Cover Leakage

When I recently did my first valve adjust I put on new gaskets from PP, they were a "graphite-type" the old ones appeared to be fiber with a blue sealant on the sealing edges. The new ones seem to leak and I've retorqued them once. Anyone have experience with this?

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Old 12-31-2003, 11:21 AM
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Hi Hugh,

I too have used the gaskets from PP. No problems however.

Try checking out the following (when doing so give special attention to the points where you see oil leaking from):

1 - Are both the valve cover and the head surfaces absolutely
free of any old gasket material or junk build up? Cleaning
these surfaces up properly so that they are base metal (if its
been negleted by previous owners/mechanics in the past) is
a pain and may take time. But it's worth it as it is essential
that these surfaces be clean for proper sealing. In addition,
once done, it will be easier to clean (or keep it clean) in the
future.

2 - Were the cover nuts torqued down starting with the center
most nuts and working your way out?

3 - The generally accepted torque spec for the nuts, I believe is
based upon a factory gasket. Perhaps the graphite-type is
a sufficiently different enough material that the torque value
may also be different? While I used the factory spec and did
not have leaks, perhaps I may have gotten lucky?

4 - Are the valve covers truly flat? If they are warped, when
mated to the head, the seal will not be sufficient.

Regards,
Carlton
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Old 12-31-2003, 12:31 PM
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Hi Hugh,

First, lets clarify, are we talking about the upper or lower valve covers (both can leak)? Its my understanding that the upper covers use the gray gaskets and the lower covers use the green (preferably with the silicone bead). There is also a new version available from those dreaded performance folks that is reusable, I think its solid silicone, and thicker for better compression against the head.
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Old 12-31-2003, 12:31 PM
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Hugh,

I went around and around with leaky valve covers, trying various combinations of gaskets and torques. I fixed the problems by resurfacing top and bottom covers. Most of the leaking was coming from the lower aft corners of the upper covers. If the covers are flat, then the gasket is not going to make a big difference. Good luck.
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Old 12-31-2003, 02:11 PM
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Exhaust covers, I think they're Turbo (they have heavy raised ribbing). Were cleaned pretty well, also the mating surfaces. Yes started in the center and worked my way out. Perhaps I should try re-torquing when they're cold, did it warm before. Thanks for the advise. I'll check all.
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Old 12-31-2003, 04:29 PM
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Hugh,

The torque spec has been 6 lb-ft for those M8 Nyloc nuts since the 1983 issue spec books came out! That is actually a lower torque than the M6 sump plate nuts!

What torque spec did you use, and did you use a 1/4"-drive torque wrench? A larger torque wrench will NOT give accurate results at such a low torque value!

For those without a 1/4"-drive torque wrench, I normally recommend using a combination 13 mm wrench and 'choking up' with four fingers of your weak hand ... close to the box end of the wrench that you have on the M8 nut. The likelihood of overtorqueing is minimal with that technique.
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Old 12-31-2003, 04:43 PM
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thanks warren! i like your suggestion, a short weak moment arm!
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Old 12-31-2003, 05:05 PM
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I use Warren's method. I also know that leaking should not occur, and is not the gasket's fault. I don't even care to replace gaskets when I do valve adjustments. Don't need to. If the mating surfaces are clean and straight, leaks will not happen. If a valve cover is not straight, it can be straightened by placing it on a big belt sander. You know, one of those tabletop belt sanders. In essense this would grind a new surface on.

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Old 12-31-2003, 05:16 PM
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