Subscribe by Email
Today, we want to talk about timing belts. Many drivers know they’re important, but they don’t know why or, more importantly, what happens if that blessed belt breaks. Best case scenario: Your vehicle stops running on the spot. Your engine shuts off; your car isn’t going anywhere without a tow truck. Worst case scenario: All of the above, plus you’re likely looking at thousands of dollars of engine damage because an untold number of internal engine parts have collided at high speeds.
Here’s why this simply named belt can cause such a tale of woe: It ensures that key engine components move into the right position at the right time. As you may know, the engine’s power is generated in the cylinders. A piston rides up and down in the cylinder. During the first down stroke, an intake valve at the top of the cylinder opens and air and fuel is drawn into the cylinder. (Click the video above for a video illustration of how this works.) Then the piston returns to the top, compressing the fuel and air mix. At the top, the spark plug fires, igniting the fuel and pushing the piston down. As the piston once again returns up in the final stroke of the cycle, an exhaust valve opens at the top of the cylinder and the exhaust is pushed out. The coordinates the opening and closing of the intake and exhaust valves. It’s called a timing belt because the valves have to open and close at just the right time.
Not all vehicles have timing belts. Some have timing chains. Like the name implies, they use a chain rather than a belt to perform the function. It used to be that most engines used timing chains, which are extremely durable. Manufacturers started using belts rather than chains to save money in the manufacturing process.
If your car has a timing belt, replacing it will be part of your maintenance schedule, and on many cars, a new belt is recommended at 90,000 miles. (Ask us or check your owner’s manual.) If you neglect to replace it, the design of your engine will determine whether your car simply stops running or if you’ll be left with a costly repair decision. There are two broad categories of engine design: interference and non-interference. If the timing belt on a non-interference engine breaks, the engine simply stops running. That could be very dangerous depending on where you are at the time, but it causes no internal engine damage.
Interference engines, on the other hand, will get real messed up when the timing belt breaks, because the valves will moving down into the combustion chamber as the piston is moving up into it. The valves and pistons can’t withstand the force of the high-speed impact, and you won’t know the extent of the damage until the cylinder head is disassembled. It can easily cost thousands to repair the engine.
So, what are the warning signs that the belt might be about to break? Unfortunately, there really aren’t any. There aren’t telltale sounds. In some vehicles, a technician will be able to glimpse part of the belt for a visual inspection, but many have a cover that’s in the way. The reality is that if the belt slips even one notch, it might as well be broken for all the damage it will cause. There’s no middle ground.
We’ve painted a grim picture here, but we would rather lay out it for your now than watch you learn the hard way. Sometimes, you can get away with ignoring the timing belt, but you have to ask yourself: Is it worth the risk? Even if the engine isn’t damaged, do you want to deal with the stress, inconvenience and cost of unexpected breakdown?
What does it cost to replace a timing belt and avoid a tow truck? It varies with the type of car you have, but in general, it ranges from $550-$1,000. This is because it’s a time-consuming procedure and because it’s smart to replace the water pump at the same time. The timing belt is attached to your intake and exhaust valves (the top of the engine), as well as pulleys that run off the crankshaft (in the lower portion of your engine).
Your technician will have to remove a number of components and covers just to access the belt. And then once s/he’s in there, the water pump is usually right there. By the time you replace the timing belt, the water pump has 90,000 or more miles on it. It has a limited lifespan. For the cost of the pump (and sometimes a tad more labor), you can ensure you’re problem-free for the next 90,000 miles. But if you leave the old pump in there and it begins to leak in another 10,000 miles, you’re paying for the entire timing belt procedure again.
When you weigh all your options, you’ll see that this is one clear-cut case of “an ounce of prevention is worth a pound of cure.”
No Comments so far
Leave a comment
Leave a comment
Line and paragraph breaks automatic, e-mail address never displayed, HTML allowed:
<a href="" title=""> <abbr title=""> <acronym title=""> <b> <blockquote cite=""> <cite> <code> <del datetime=""> <em> <i> <q cite=""> <strike> <strong>