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I replaced my valve cover gasket and the spark plug well sealer gaskets on my 2004 Mitsubishi Lancer recently because of an oil leak. The previous owner (or his mechanic) had over-tightened the bolts on the valve cover and which has resulted in some deformation of the cover around the bolts. I also noticed some marks on the inside of the cover indicating that two of the valves have been touching the valve cover at the top of their stroke.

The issue I'm now facing is that when I tighten the bolts on the new gasket to the specified torque I get oil leaking into the spark plug wells.

I tried tightening the bolts a bit more and that causes all the valves to knock on the cover. I loosen them and I get the leak in the spark plug wells again.

What do you guys think of using some RTV to fill the gap between the spark plug well gaskets and the cover?

What are the risks?

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    My suggestion, and only a suggestion, is to pop for new valve covers. Once they start leaking it's almost impossible for you to get them not to, mainly because they are warped and no longer want to play. – Pᴀᴜʟsᴛᴇʀ2 Apr 23 '16 at 2:31
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    A picture of the deformity of the valve cover would be helpful too. – DucatiKiller Apr 23 '16 at 2:36
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I'm not a fan of RTV

Others that are professional and hobbyists don't agree with me but, some do.

I just don't use RTV, it's like duct tape to me. I get a physiological reaction to the acronym. I feel it has it's uses in very rare cases.

Why don't I like RTV?

Because if use too much it can create a bead inside of the motor and then eventually break free and clog up the oil pickup or an oil galley of some sort.

Some have argued, "it will never get past the oil pickup and then it has to get past the filter, it's not going to happen." Yes, I agree with that. It won't get past a filter and probably won't get past a screen.

In order to clog a screen in an oil pickup there would have to be a lot of it in the oil system getting picked up but.....I had a boss once that would call me a junk mechanic in a super thick Korean accent all the time and if ever saw a tube of RTV in my hand he would scream it.

So, this could be built around my own psychological damage. Regardless, there is logic here. It CAN clog your oil pickup screen and if it doesn't it's litter in your engine. Basically trash floating around in there. I'm not a fan of that.

So, that's why I won't use it. The circumstances have to meet a criteria for me and this doesn't meet them.

Can you flatten out the bent in valve cover bolt holes? I haven't seen a pic but I would argue yes. If it's a sheet metal valve cover, can't be alumunium if its bent, you can flatten out those bends carefully with a hammer and a flat surface. That's what I would do.

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Usually, there are 2 types of valve cover gaskets - rubber and cork. RTV should not be used with rubber gaskets.

For cork ones, I will sometimes cover the gasket in RTV. Put the gasket on a box, put some RTV on your finger and wipe a thin layer on each side. This will allow it to bond to the cylinder head and valve cover, but will not be thick enough to squeeze out.

As others have said, it sounds like the root of the problem is the valve cover. If you can, the cheapest solution would be to get one from a junkyard.

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