How long can I go with a leaky headgasket before killing my engine?

Dear Car Talk

Dear Car Talk | Oct 01, 2005

Dear Tom and Ray:

Guys -- I love your show and your column, and have followed them from NY to NJ to IL to NJ to NY to NC to NJ again. My wife's superb purchase of a 1996 Toyota Camry, which has been a workhorse for almost 10 years and 110,000 miles, apparently now has a head-gasket leak. I have never had to add oil between oil changes. So, I guess I can spend $2,500 now to fix it, or take my chances and maybe need a new engine one day. How long can I get away with just watching the oil-pressure gauge and dipstick? Weeks, months, a year or two?

Thanks. -- Steven

RAY: Well, I've been watching this dipstick next to me for years, and all he does every day is roll under a car and fall asleep.

TOM: Well, our creeper is too comfortable.

RAY: Yeah. We need one with spikes on it. Anyway, it depends on what kind of leak the head gasket is causing, Steven. A cracked head gasket can create several kinds of leaks.

TOM: It can allow oil to leak from the oil passages to the outside of the engine. You'd be able to see that. You'd see oil seeping out where the cylinder head meets the block.

RAY: If it's leaking oil at such a slow rate that you never have to add any between oil changes, it might leak for years like that and be just fine. So, that's the best-case scenario.

TOM: However, if it's letting oil mix with your coolant inside the engine, then you've got to fix it. The problem isn't so much the oil that gets into the coolant, as the coolant that gets into the oil. Coolant is a lousy lubricant, compared with motor oil. Trying to lubricate an engine with a mixture that's half antifreeze is going to make you sound prophetic, Steven. Because you WILL need a new engine one day -- one day soon.

RAY: The same can be said if a broken head gasket is allowing coolant to get into the cylinders. That means you're burning up your coolant and it's coming out your tailpipe. At some point, the leak will get a lot worse, and you won't notice until you run out of coolant and turn the engine into a solid, single-piece, 600-pound paperweight.

TOM: So unless it's only leaking oil externally, and slowly, I'd recommend that you go ahead and fix it. If properly cared for, this engine could easily go another 110,000 miles. Failing to fix it could result in having to buy your wife a brand-new Camry --which, as you know, Steven, is a heck of a lot more than $2,500.

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