Gasket Science: Can You Reuse An MLS Head Gasket?

There are numerous fables in the high-performance world on what you can or can’t do with various parts. One of the more common ones out there is that reusing MLS head gaskets is perfectly fine, but just because you hear something is true doesn’t mean it is. We talked with Mickey Hale from Cometic Gasket to see if you can, in fact, reuse an MLS head gasket.

Head gaskets are really what helps to keep all the fire inside the engine where it needs to be during operation. If a head gasket is compromised, all kinds of bad things will happen in a hurry that will hurt an engine and the owner’s wallet. Keeping the integrity of the gaskets intact will keep an engine running right and making plenty of power, so using a fresh gasket is very important.

According to Hale, the myth of being able to reuse a MLS head gasket has been around for a while, but it’s a bit misguided.

“While we see it on forums and message boards all the time about reusing MLS head gaskets and the success of the practice, its failure rate is much higher after reuse. The reason behind this is: once the gasket is heat cycled, the embossments will not spring back to where they were originally. In a mock-up situation, it is perfectly acceptable to install, check clearances and reuse the gasket. Once heat is put to the gaskets, the ‘spring’ is gone and since the embossment is the sealing area, there is a greater chance of a coolant or compression leak.”

Now, if you’re in a total bind at the track and need to reuse a gasket for only a handful of runs it’s not ideal, but it can be done. If you’re trying to reuse a head gasket as a long-term solution, that’s opening a dangerous door to many problems. The risks involved with not using a fresh MLS head gasket far outweigh the benefits enough to make it a good idea to keep a spare set on hand at all times.

“Besides the cooling leakage or a compression loss, oil retention could come into play. Most times with any MLS-type gasket, any leak is contributed to three things not being in play: proper torque settings, proper surface finish, and the gaskets not being fully compressed. An MLS gasket, when all three of these factors are correct, will not leak and hold a great deal of cylinder pressure. I would also say that adding an addition sealer, while it may seem like a good idea, really isn’t. The gasket already has a sealer on it, adding another layer of copper coat or similar keeps the gasket embossments from compressing fully to do what it was meant to do; think of it as hydraulicing the gasket in theory,” Hale explains.

If you want to learn more about MLS head gaskets and other engine sealing components check out the Cometic Gasket website right here.