The timing belt is a sturdy belt made of nitrile rubber with fiberglass mesh re-enforcement. It has lateral ribs or cogs on the inside surface that engage with various sprockets. It is very strong and resistant to heat, chemicals and oil.
What does it do?
It is used to keep internal engine components moving in sync. Most importantly, it controls the opening and closing of the exhaust and intake valves, which bring fresh air into the engine and allow exhaust out. In some vehicles it is also used to drive the water pump.
Why does it matter to me?
Just like fan/serpentine belts, timing belts wear out. Because most timing belts are difficult to properly inspect, manufacturers provide recommended service intervals. Most are about 100 000 to 120 000 kms, but it varies. Please ask us about yours, or you can find it in your owner’s manual. (Note: Often two intervals will be given, one for normal service and another for severe service. Ontario winters qualify the operation of most vehicles as severe service, so the shorter service interval should be followed).
What happens when it wears out?
Sometimes a weak belt will just skip over a few teeth on one of the sprockets. This can cause a vehicle to run poorly (because the valves open at the wrong time) but usually still allows it to start. Eventually a weak belt will lose a significant section of ribs or break entirely. If this happens, the engine will immediately stop and the vehicle will not start again until the belt is replaced.
Is that it?
Unfortunately, no. Some vehicles have a particular engine design called interference fit. This means that the components which the timing belt keeps synchronized (the valves and pistons) cross each others’ paths during engine operation. When the timing belt is doing its job, these components are never in the same place at the same time; but when the timing belt skips or breaks, they can collide. If they hit with enough force, things can be bent or broken. Usually the weakest components, the valves, give way. The only fix for this is to remove and rebuild the head, or the top part of the engine, which is a relatively expensive and time-consuming operation.
So what should I do?
Find out if your vehicle has a timing belt, what the manufacturers’ recommended service interval is, and if the engine is interference fit. This is all contained in your owner’s manual, but we’d be happy to look it up for you. Then consider your mileage and if the belt has already been replaced. If you are over the mileage and unsure if it has been replaced, we recommended working it into your maintenance schedule as soon as possible, especially if your vehicle’s engine is interference fit.
What does the job involve?
Most timing belt procedures are in the three to five hour range, though it varies. A new belt is required, of course. Also, most timing belts ride on idler pulleys, some use hydraulic tensioners, and sometimes they drive the water pump. Because of the complexity of the job, most manufacturers recommended replacement of these other timing components whenever the timing belt is serviced. At Red Truck Automotive, we are equipped and experienced to handle the vast majority of timing belt service on all makes and models. Ask us for a quote today!
Remember, maintenance makes sense!