Timing Belt
Ever heard the sad tale of a staggeringly steep repair bill from a broken timing belt? Bad news. Let’s take a lesson from their woes and remember to think about our timing belt.
First, let’s review what a timing belt does. The top part of the engine over the cylinders is called the cylinder head. The head contains the valves. There’s at least one valve that lets the fresh air into the cylinder. This air, mixed with fuel, burns to create power. Then another valve or two will open to allow the exhaust out of the engine. Each cylinder has 2 to 4 valves – that’s 12 to 24 valves for a V-6, up to 32 values on a V-8. The opening and closing of the valves is done by a camshaft. The timing belt uses the rotation of the engine to drive the camshaft which opens and close the valves. It’s called a timing belt because it has to be adjusted to rotate the camshaft to keep proper time with the engine so that everything’s in sync.
The timing belt is a toothed rubber belt. But some vehicles use a timing chain or timing gears instead of a belt. Timing chains and gears are much more durable, but vehicle manufactures are using belts more because they are quieter – and cheaper. If you have a small or mid-sized passenger car, crossover or mini-van, chances are you have a timing belt.
Someone we know, who shall remain anonymous, has had two timing belts fail. The first was while he was waiting at a stop light – that repair cost several thousand dollars. The second was while driving on the highway – that one cost more than twice as much. Both had the cars out in the shop for three weeks. His cars had what we call “interference engines,” meaning that the valves and pistons are very close to each other. If the timing belt slips even one notch, the pistons will slam into the open valves. That’s why our friend’s highway failure was so much more – his engine was traveling so fast that the valves were smashed and they chewed up the cylinder head.
A non-interference engine will just shut down if the timing belt breaks. You’re stranded, but the engine doesn’t suffer permanent damage. In both cases, our hapless friend was just a couple oil changes past the recommended interval for changing the timing belt. This is one of those things that Tucson drivers just cannot put off. Now replacing a timing belt is not cheap – but repairs for a broken belt can be far more expensive.