Reusing an MLS headgasket?

[Mean Green]

I've never done it before but I cannot afford to buy yet another. I torqued it down and ran it for a few minutes without it getting to full operating temperature. It has probably 5 minutes on idle time.

Considering I have never reused one before, any precautions I should take?

[blindmist]

I've never done it before but I cannot afford to buy yet another. I torqued it down and ran it for a few minutes without it getting to full operating temperature. It has probably 5 minutes on idle time.

Considering I have never reused one before, any precautions I should take?

Chances are if it has sealed (do a compression test) you are fine. You will only lose the seal if you run too much boost (read 20-30psi) or overheat. Once the crush seal has been made, it stays until something goes seriously wrong.

[Mean Green]

Chances are if it has sealed (do a compression test) you are fine. You will only lose the seal if you run too much boost (read 20-30psi) or overheat. Once the crush seal has been made, it stays until something goes seriously wrong.

So I should be fine to reuse it? Should I put copper spray on it or anything like that?

I pressurized all the cylinders to 40 psi and could only hear crank case ventilation which is normal givin the fact that the engine has not been properly run in yet. Compression is now 150~155 on all cylinders except cylinder 2 which is the problem cylinder. I already got 2 new intake valves so all I should have to do is lap them in.

[blindmist]

So I should be fine to reuse it? Should I put copper spray on it or anything like that?

I pressurized all the cylinders to 40 psi and could only hear crank case ventilation which is normal givin the fact that the engine has not been properly run in yet. Compression is now 150~155 on all cylinders except cylinder 2 which is the problem cylinder. I already got 2 new intake valves so all I should have to do is lap them in.

I would say you are probably ok. There is never a 100% though so just keep that in mind. I wouldn't use copper spray. Assuming you are putting the exact same heads back on that came off correct? You haven't done any machine work to them correct? As long as it is the exact same surface that it came off of you still have a good chance and getting a proper seal. Just make sure everything is as clean as can be. I even mean to the point of wearing latex gloves to keep the oil from your skin from getting on the gasket surface on the block and head.

Edit: Let me just throw a personal experience in here. I was working on a 4G63T. Reused the Cometic MLS head gasket, it worked great until it over heated just a little. As long as you have no cooling issues, or a FMIC, you are probably safe.

[Amphiron]

You should be okay. I torqued my heads and then had to removed them and used the same gaskets with my new heads. The engine is okay for now, but I am going to buy a set of head gaskets to keep around just in case. You should be okay for awhile. Just don't get it super hot.

[Mean Green]

I cleaned it off until it was bone dry and it didn't even look like it had been installed before. I cleaned the head and block until they where bone dry as well. Installed it, pressure tested the radiator, oil system and each cylinder, no leaks.

[Ondonti]

Copper Spray it. Nothing wrong with that. The stuff gets pushed out if it shouldn't be there.
Ive reused the same cometic set like 4 times, until I melted one of them while pushing coolant.


And that thing about cometic gaskets is wrong. They are not thicker around the bore, the thin outside layer is formed to look thicker but when clamped down it flattens.

Ive seen Pressure film tests comparing OEM mitsu MLS and cometic gaskets and the OEM clamps harder around the bore, indicating it is thicker there when compressed.
Thicker around the bore is a good thing if the tolerances are correct and the thickness is not so great that the rest of the gasket does not seal.

[jba3]

+1 on the copper spray, reusing should be fine if it isn't damaged

[Ondonti]

PS, I was able to get 100k mile paper headgaskets that were removed, sat in a shed for 4 years....to seal when copper sprayed. Leaked water at first. Heat cycled the motor (get it hot and cool down) and it fully sealed the leaky water passage.

[Mean Green]

Well, like I said, normally I would never reuse a headgasket but this one didn't even get heat cycled. I pulled it off and none of the black color pealed off onto the deck or the head.