Multi-layer steel head gaskets have become all the rage lately, especially in high-stress racing engines, and Fel-Pro has a complete lineup of product in its catalog. There is an MLS gasket for just about every application. In fact, Fel-Pro’s Ron Rotunno says, “”We have more than two dozen models alone for the LS line of engines.”

However, one item that constantly comes up in discussion during the installation of said gaskets is whether they should be sprayed with sealant upon installation. In fact, Rotunno says it’s probably the most-asked question of the show from his perspective. 

And the answer? Quite simply, no. “We do not recommend spraying Fel-Pro multi-layer steel gaskets with copper sealant or any other substance. They should be installed dry right out of the package,” he says. “We can’t say for sure that sprays won’t react in some way with the rubber coatings. You could get also overspray on top, which could lead to leakage, or you could get spray between the layers, which will also cause sealing issues. Finally, when it’s time to take the engine apart, it’s a much cleaner job without any type of spray.”

The four-layer gaskets (three active layers, one shim layer) perform like a spring to maintain consistent contact pressure between the engine block and cylinder head.  The gaskets are embossed to prevent fluid leakage around critical areas.

There are two different types of rubber coatings used on the MLS gaskets from Fel-Pro. OEM and OEM-replacement applications use a softer blue coating that’s designed to seal surface finishes that are a bit rougher, and provides more leeway when engine machining is not superior as it would likely be in a racing application. 

The black coating is a bit harder and doesn’t conform to those surface imperfections as easily as the blue gaskets do, but they aren’t designed to do so, as most racing engine builders have the capability to provide fine surface finishes that are able to make use of the black gaskets’ sealing properties.

In addition, the black coating is much more durable and will withstand much higher chamber temperatures.