At Peak Auto in Apex NC and the Cary NC area we perform routine maintenance on timing belts and water-pumps for vehicles that have them. Some vehicles have a timing chain instead of a belt. In theory the chain is supposed to last for ever but on many of the Mini Cooper engines made by Peugeot the chain stretches sometimes as soon as at 60,000 miles. This can cause a check engine light to come one because it changes the timing.
Manufacturers recommend replacing your timing belt anywhere between 65,000 and 105,000 miles depending on the vehicle and engine. It is best to check your user manual or call us at Peak Auto 919-363-8589 and we can look it up for you in our auto industry resource center. Most service centers recommend replacing the water pump when replacing the timing belt because the water pump is typically driven by the timing belt, not always, and is located just behind the timing belt. There is not much more labor to replace the water pump and they typically last as long as a timing belt. The thought here is that you would replace your timing belt at 100,000 miles and then 5,000 miles later your water pump would start to leak or fail in another way and you would have to remove the new timing belt to access the water pump. If the coolant leaked onto the timing belt, you would have to replace that again as well.
There are a few other items that are replaced with the timing belt and are usually included in the timing belt kit. Each engine is different but the list can include a few pulleys and tensioners. On some Volkswagen, Audi’s, and Toyota’s there is also a timing belt hydraulic tensioner that should be replaced but is not included in the kit. Idea here is that all these moving part are old and worn and if they fail with the new timing belt, it will cause the timing belt to fail which could lead to valve damage and a whole lot of money to fix.
What could happen if a timing belt fails. Two things, damage valve and top end of engine or not. Some engines are not interference engines and if the timing belt breaks then no damage, but the vehicle will not run. Most vehicles do have interference engines, if the timing belt slips, or breaks then valve damage is pretty imminent. We have seen on occasion an interference engine that the timing belt breaks and there is no valve damage, all I can say is very very very lucky for the customer. Why don’t they make all engine non interference you may ask. Because of performance. It all has to do with how far up the pistons rise in relation to the bottom of the valve. The more compression an engine has the higher the piston needs to rise.
As with all service listed in your vehicle listed in your service manual, keep up to date with it at Peak Auto Cary NC and Apex NC and all will be well.