As your engine runs, the intake valves need to open up to allow air into the engine. They remain closed while the air and fuel is compressed and ignited, powering the piston. Then the exhaust valves open to release the exhaust. This all has to be timed very precisely. It is the job of the timing belt or timing chain to make sure all of this is synced up properly.

Timing belts are made of a very tough compound that can last for tens of thousands of miles. Timing chains are made of metal and last for a very long time as well. If your vehicle has a timing belt, your owner’s manual has a schedule for replacing the belt. If your vehicle has a timing chain, there may not be a specified schedule for replacing it, but that doesn’t mean that the timing chain system is indestructible and never needs attention.

For example, the chain runs on sprockets on the crankshaft and the camshafts. A broken tooth on a sprocket can cause the chain to slip a little. When timing is off a little your engine will not run as smoothly. When timing is off enough your engine won’t run at all and could even be severely damaged. There is also a tensioner that keeps appropriate pressure on the timing chain. This keeps the chain tight while allowing it to absorb pulsations from the engine. The tensioner can wear out. There are also guide rails that keep the chain on the proper path that can become worn.

The bottom line is that at some time, one or more of the timing chain system components will become worn to the point that they are no longer performing within specification. Your service advisor can help you with recommendations for when timing chain components should be replaced on your vehicle and have it inspected for signs of timing chain system wear.

Since timing chains are lubricated by engine oil, staying on top of your regular oil changes is very important to long life. Always use a high quality oil filter and oil of the recommended type and grade.

Timing Belt Repair & Maintenance / Replacement

Let’s address a very important maintenance item – timing belt replacement. It’s important because letting this one slide can lead to very expensive engine damage.

Your timing belt choreographs the timing of your combustion process. Your pistons travel up and down in the cylinder. Intake valves open at the right time to let in air and fuel, they close at the right time to allow the fuel to burn and then the exhaust valves open at the right time to let out the exhaust.

All this happens thousands of times a minute and it’s your timing belt that makes sure the valves are opening and closing at precisely the right time. If the timing is off, your engine won’t run. And that’s the best case.

The worst case is that a valve is opening at the wrong time and collides with the piston. The result is bent valves and maybe even more damage to the cylinder head. Repairs can run several thousand dollars.

Now, timing belts just wear out naturally so you want to replace a worn belt before it slips or breaks. Check your owner’s manual or with your service advisor to see when they recommend you replace the timing belt. If you’ve never replaced your timing belt and have 60,000 or more miles on the clock, talk with your service advisor right away to see if you’re due.

On some engines, the water pump is driven by the timing belt as opposed to the serpentine belt. If that’s the case, it’s a good idea to replace the water pump when you’re replacing the timing belt, and vice versa since much of the same work has to be done for either. The same is true for the timing belt tensioner – it should be inspected and possibly replaced.

Now, replacing a timing belt is one of the more expensive routine maintenance items on your service schedule. But not replacing your timing belt can lead to some of the most expensive repairs you’re likely to ever have.

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