What can I do to prevent yet another head gasket from blowing?

Dear Car Talk

Dear Car Talk | Sep 01, 1992

Dear Tom and Ray:

I've had some costly experiences with blown head gaskets. Never having read or heard of preventive measures, I wonder if periodic re-torquing of the head bolts would help. What is your advice?

TOM: You must have gotten a torque wrench for your birthday, Edgar. And now that you've already tightened everything in the house--the kitchen faucet, the bedroom doorknobs, the toilet flange--you're looking for something else to do.

RAY: And even though re-torquing the head sounds like a great idea, most manufacturers don't recommend it. It's just not necessary, and unless your owner's manual specifically calls for it, we don't recommend it either.

TOM: The best way to prevent your head gasket from blowing is to make sure the engine doesn't overheat. Most modern cars now have aluminum cylinder heads and cast iron engine blocks. The head gasket is the seal that goes between them.

RAY: And the most common reason head gaskets break is that they get stretched past their limits. When the engine heats up, the block and the cylinder head expand. But since they're made of two different metals, they expand at different rates. The head gasket is designed to allow for a certain amount of stretching, but when the engine overheats, the cylinder head expands too far, and the head gasket can't take it, and breaks.

TOM: So, here's the best preventive maintenance. First, make sure you cooling system is in good condition--especially the belts and hoses. And second, if the car ever does overheat, pull over right away and shut off the engine. And if you start to get a little antsy sitting by the side of the road, console yourself by thinking about all the other marginally useful tools you can buy with that $400 you're NOT going to have to spend on a new head gasket.

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