Roadshow

What's a head gasket? And why does it cost so much to fix?

This expensive car repair is maddening. Here's why.

CNET

I hate head gaskets.

That may seem like an impractical statement about a part that allows the two halves of your engine to work together, but it's a part that fails spectacularly, expensively and all too often in an era when little else fails on modern cars.

The head gasket is a piece of thin material with a lot of holes in it. 

head-gaskets

Head gaskets are thin wafers of material that seal engine blocks to cylinder heads. They contain pressure from combustion, oil and coolant to keep each in its own lane.

Victor Reinz

It seals the engine head, where the valves reside, to the engine block where the pistons live. It prevents compression, combustion, oil and coolant from escaping or mixing with each other in the channels running between the two major assemblies of the engine.  

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When even a small part of the head gasket is breached, or "blown," your car will run poorly -- if at all -- spewing white or blue smoke from the tailpipe and burning through a lot of oil, coolant or both. 

The repair is to replace the gasket entirely, which involves removing about half of the engine to get to it. And when you've invested the labor to tear down the engine that far you often address other things like valve reconditioning, timing chain replacement, water pump service, or intake and exhaust gaskets. That's why a head gasket job is seldom just that. It usually starts around a grand and can easily hit several thousand dollars. 

Easiest way to avoid this expensive nightmare? Get an electric car. They don't have engine blocks, cylinder heads or head gaskets mating the two. Problem solved.