Kai's neighbor's car is making a loud ticking noise. Is it about to break down?

Dear Car Talk

Dear Car Talk | Aug 01, 2006

Dear Tom and Ray:

I am writing to you regarding my neighbor's car. I think it's about to break down. Now, normally I wouldn't care, but the thing is, I don't have a car, and my neighbor gives me a ride down to the bus stop every morning. I really don't want to walk 4 miles every day at 6 a.m. Anyway, the car is making a profusely loud ticking noise. I looked under the hood, and it seems to be coming from the top of the engine. It's an Oldsmobile station wagon, like a 1990-something-or-other, with a V-6 engine, front-wheel drive and an automatic transmission. There is no "Check Engine" light coming on. I looked into the oil level and found that it was almost bone-dry. I filled the oil up all the way, and it's been holding this oil, but the noise never went away. What could be the problem, and what can I do (or get my neighbor to do) about it? Thanks for any useful advice (assuming you have some, of course). -- Kai

TOM: You want useful advice? Move closer to work, Kai.

RAY: It sounds like a collapsed lifter or a worn-out cam-shaft lobe. There's not much you're going to be able to do about either of those things at this point.

TOM: Here's how it works. When the engine is running, the cam shaft spins. Each time a high point -- or cam lobe -- comes around, it pushes on something called a hydraulic lifter. That, in turn, pushes on something called a push rod. The push rod hits the bottom of a rocker, which is like a seesaw. When the other end of the rocker gets pushed down against the valve stem, the valve opens. That lets air and gasoline into the cylinder, which keeps the car running.

RAY: Now, you might ask, how do all of these pieces stay in perfect adjustment through the years? Good question, grasshopper! The answer is that the hydraulic lifters adjust automatically.

TOM: The hydraulic lifters constantly get filled with oil from the oil pump, and that allows them to expand to take up the slack that gets created as the other parts wear out.

RAY: So, either one of your neighbor's lifters is no longer holding oil or, more likely, a lobe on the cam shaft has been worn down to a nub.

TOM: So instead of a few thousandths of an inch between those parts, he's got about 3 feet. OK, maybe a quarter of an inch. Those pieces slapping together are causing the loud ticking noise.

RAY: This car is running on about five and a half cylinders. Now, on some cars, this ticking will go away after a few minutes. That means it's not that bad yet. So maybe after he drops you off at the bus stop, he keeps driving, and the ticking eventually stops. But if not, it requires a pretty serious repair, and it's not something you're going to be able to do for him.

TOM: My advice would be: Don't worry about it. Continue to check his oil for him once a week, and top it off when necessary. That's a nice thing to do in exchange for the ride you get every day. And give him a case of Gunk Oil Treatment for the holidays. That might quiet it down some. And in the meantime, save up for a pair of in-line skates.

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