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Q: Timing belt needs replacing

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My car won't start. I think it might be the timing belt.

A: If your car is not starting, and you suspec...

If your car is not starting, and you suspect the timing belt, the first thing we could do is have the belt inspected. Remember, when the timing belt breaks only half of your engine is turning. This is why you hear a very characteristic sound while the motor is spinning and you don't hear the "puffs" or coughs you normally hear when a cylinder makes compression. Also, it will spin much faster if there is a brake in the belt. The bad news is that a lot of engines are built in a manner that do not permit this. When a belt breaks the bottom half of the engine continues to spin but the camshafts stop moving. That means the valves stop moving.

Let's say this happened when both intake valves for cylinder 1 were open. Now, if the engine were an "interference engine," when the piston got to the top it would slam into the open valves because it was not built with enough clearance for valves to be open when piston was at top. In an engine like this, when the belt brakes and serious engine damage occurs, this will usually require an entire engine replacement. So checking to see if your car has an interference engine would be the second thing on our list. An inspection of a mechanic will let you know if your timing belt needs replacement. Sometimes it will be okay to only replace the timing belt, however the best way to do this job would be to replace the idlers, tensioners, and water pump, along with the timing belt to ensure that all new components work well together.

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