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Head gaskets deal with a lot more abuse than you might expect. It's a miracle they last as long as they do. Food Grade Rubber Washers

Head gasket failure is a common engine killer. Anyone who's spent hours wading through Craigslist ads for high-mileage Subarus and 4Runners knows it. A component we never think or talk about goes, and suddenly there's a four-figure repair quote on the service manager's desk. It's infuriating, but after watching this New Mind video on the stress these gaskets are under, it's a lot easier to understand.

The video calls head gaskets the "most tortured part in an engine" and, after watching it, I'm convinced. While other components are under much more stress in certain ways—piston heads have to deal with higher heat, drivetrain components have more mechanical stress—the head gasket is under every conceivable type of stress, constantly. It must withstand the extremely high clamping force of the head bolts without deforming too much, but still be ductile enough to effectively seal a rough surface. It has to deal with the thick sludge of cold oil and the high-pressure watery flow of hot oil, right alongside coolant flows. Those two fluids can never mix and both contain corrosive components, debris, or additive.

On top of all of this, the gasket must contain the pressures of the combustion chamber. It must be highly heat-resistant to handle temperatures in excess of 1000 degrees Fahrenheit. All of this must be true whether it is -30 and the engine is cold or on a 100-degree day going uphill with a trailer. The sheer flexibility required is absurd, which is why it took a long time for us to figure out how to make gaskets that last.

Head And Gasket The video breaks down how early automotive engineers tried to solve these problems. It takes you through the main innovations that have made them better over time and, finally to the modern multi-layered steel head gasket. It's a fascinating piece of engineering and, he points out, likely the last evolution before the internal-combustion engine goes out of style. If you're nerdy about the details, it's worth a watch.