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What is a timing belt or chain?

In older vehicles, this might be a timing chain.  For simplicity, we’ll use the more modern “timing belt” for the remainder of this article.

A timing belt may be a difficult thing to understand, but you don’t need to be a car expert to understand your car.  A timing belt keeps your engine “timed”.  It keeps parts in the top end from hitting parts in the bottom end.

Think of it like gears and a chain on a bike.  Without the chain the gears won’t move.  A combustion engine needs its gears connected too.  Just like if your bike’s chain broke, you would not be able to pedal, the timing belt is just as critical.

How can the timing belt break?

Before we can talk about what timing belt failure means, we need to talk about how they can fail.

  • The belt breaks apart : This is where the belt separates. We haven’t seen many do this, but it is possible.
  • The teeth sheer come off the belt : The belt is “toothed”. That is how the belt turns the gears. I have seen many many timing belts with teeth missing from the belt.
  • Seized, or failed component in the belt circuit : There are also parts that keep tension on the belt. If a tensioner fails, it can cause the belt to be too loose. That can cause the belt to skip and become out of time. If a component seizes, it can rip the teeth from the belt.
  • Outside influence : Whether it is damage from a wreck, or a bolt came out of the engine. Outside influence is bad news.

How to check a timing belt.

For some vehicles this can be a difficult thing. Timing belts are generally covered up to keep debris out. This can also make it hard to check your own belt. If you can get to the belt, you can do a little checking.

  • Look for cracks – Check the belt for surface cracks.
  • Belt deflection – Basically see if the belt is loose. This can be tricky. Find the section of belt that has the furthest distance between gears, or tensioners. Some belts have a spec, generally it is twisting the belt ~90 degrees.
  • Listen for noises – When tensioners and rollers go bad, they can make noise. They don’t always make noise. If they do, it is time for replacement.
  • Check for leaks – A leak from a belt?  Well, not exactly. However leaks from a water pump or an oil leak can damage the timing belt.  If you have a belt that is saturated in oil or coolant, it’s time for replacement.

How is a timing belt get replaced?

This really depends on your particular vehicle and engine.

Some engines have special tools to hold the engine in place. Others have various markings that get lined up.

So, do I really this service?

This is a service that you can’t afford to pass on.  If you wait, you are really run the risk of an expensive repair.  Yes, a timing belt replacement is expensive, but you can do 3 or 4 timing belts before having to pay for a cylinder head repair.