Valve cover gasket sealing issues

north54 · Post by **north54** » Sat May 20, 2017 12:41 pm

I'll have to redo this job for the 3rd time now. I'm using the correct alloy 1/2 moon rear seal and main gasket. Applying generous amount Permatex 2 gasket maker to the edges. Both rubber bolt grommets are also replaced and torqued to the proper specs.

I just noticed the 1/2 moon seal weeping again after about a week of doing the job for a 2nd time.

I think the only reason this keeps failing is I park on an incline on the street. I assume the oil in the valve cover is collecting around the 1/2 moon seal thus eroding the gasket goop before it can properly dry. I make sure all surfaces are clean before installing the gaskets...

Is there a better gasket compound to do this job, something that maybe won't get eroded by oil?

I'll do the job again. Getting good at it!

gledhillpete · Post by **gledhillpete** » Sat May 20, 2017 3:01 pm

Red RTV has always worked for me. How much oil will linger in the valve cover? If assume it would make it's way through the galleries. Have you checked for warping?

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Post by **Growlerbearnz** » Sat May 20, 2017 3:34 pm

Yeah, I can see how that would be frustrating. I'm not sure Permatex #2 is the right sealant though- the workshop manual calls for 3M ATD8660 which is a silicone RTV, whereas Permatex #2 is a rosin-based non-hardening sealer. Consider trying Permatex Ultra Black instead.

As Pete says, check the mating surfaces for warping or imperfections (though I expect you've done that).

Thinking about how I installed the half-moon, I cleaned up the mating surfaces using a solvent (brake cleaner is good) and let them dry. Then a thin (about 2mm wide) bead of RTV on the curved part of the halfmoon, hammer it into place using a plastic mallet (or a piece of wood between a regular hammer and the halfmoon- you don't want to bruise it). Check that it's perfectly flush with the sealing surface. Then a smear of RTV as the workshop manual shows, place rocker cover on head, put bolts in and screw in the bolts until *just* touch the cover. Leave for an hour or 2, then torque the cover bolts all the way.

north54 · Post by **north54** » Sat May 20, 2017 3:41 pm

Growlerbearnz wrote:Yeah, I can see how that would be frustrating. I'm not sure Permatex #2 is the right sealant though- the workshop manual calls for 3M ATD8660 which is a silicone RTV, whereas Permatex #2 is a rosin-based non-hardening sealer. Consider trying Permatex Ultra Black instead.

As Pete says, check the mating surfaces for warping or imperfections (though I expect you've done that).

Thinking about how I installed the half-moon, I cleaned up the mating surfaces using a solvent (brake cleaner is good) and let them dry. Then a thin (about 2mm wide) bead of RTV on the curved part of the halfmoon, hammer it into place using a plastic mallet (or a piece of wood between a regular hammer and the halfmoon- you don't want to bruise it). Check that it's perfectly flush with the sealing surface. Then a smear of RTV as the workshop manual shows, place rocker cover on head, put bolts in and screw in the bolts until *just* touch the cover. Leave for an hour or 2, then torque the cover bolts all the way.

gledhillpete wrote:Red RTV has always worked for me. How much oil will linger in the valve cover? If assume it would make it's way through the galleries. Have you checked for warping?

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Thanks fellas, I'll try the red, I assume it will be much easier to spot a leak than black gasket maker... What was I thinking!

Interesting to note Growler my alloy half moon seal required no hammering to fit at all. It just fell into place perfectly. Maybe I got a defect but it was a direct mitsubishi part.

Post by **Growlerbearnz** » Sat May 20, 2017 10:41 pm

Hmm. Mine was quite tight. Let the RTV set for about half an hour before tightening everything down so there's a bit of compression on the RTV.

Lapprentis · Post by **Lapprentis** » Sun May 21, 2017 4:13 pm

Sugestion: get the Aluminium Half Moon Seal (MD372348), it may be the last time you repair it :)

See also : viewtopic.php?f=6&t=11132&p=128131&hili ... um#p128131 , etc.

Lapprentis

north54 · Post by **north54** » Sun May 21, 2017 4:15 pm

Lapprentis wrote:Sugestion: get the Aluminium Half Moon Seal (MD372348), it may be the last time you repair it :)

See also : viewtopic.php?f=6&t=11132&p=128131&hili ... um#p128131 , etc.

Lapprentis

I have it, as per my original thread!

sealica · Post by **sealica** » Sun May 21, 2017 9:08 pm

So I've just replaced my rubber half-moon (leaking after 4 months) with an alloy half moon. I wasn't entirely happy about the gob of silicone gasket maker I made at the back of the engine, but it's really awkward to exercise finesse on that difficult to see area ...

We'll see if it seals. I noticed that there were a few flakes of silicone floating in the oil inside the valve closest to the halfmoon area, from the previous gasket-maker. Something to worry about? Also there were a few circular shaped scratches on the inside of the valve cover - is this regular, or a sign of something bad going on?

Post by **Growlerbearnz** » Sun May 21, 2017 9:17 pm

Lumps of silicone sealant in the oil is not great, but as long as it's just a few from that one area it's probably ok, the oil strainer should catch them. The issues arise when people use way too much RTV during an engine rebuild and lumps of it go everywhere, clogging all the tiny oil passages.

north54 · Post by **north54** » Mon Jun 05, 2017 10:52 pm

The red RTV appears to be working after a couple weeks. Thanks guys!