So what is the difference between a timing belt and a timing chain? Fundamentally, a timing belt and timing chain serve the same purpose. Whether you drive a Porsche, Mercedes Benz or BMW with an internal timing chain or an Audi or Volkswagen with an external timing belt, these devices are designed to keep the relative position of the valves opening and closing to the position of the piston as the engine is running. Opening a valve at the wrong time can cause it to contact the piston, causing catastrophic engine failure.
A properly timing engine will allow the piston to rise (building compression) and the valves to open precisely, allowing air and fuel to enter the combustion chamber and exhaust to exit within 1000th of a second. A miss timing situation leading to valves opening or closing late or early will drive the piston into the valve, most often bending the valve and possibly punching a hole in the piston crown, rendering the engine useless. These repairs can be a minimum of $4,000 to $5,000 and on some engines, significantly more.
Porsche, BMW and Mercedes Benz make use of an internal timing chain. These chains are more durable and less likely to fail themselves. Other components used to hold the chain in position such as chain tensioners and chain guides are more common failure points, leading to the same end result. Early warning signs of a failure will be check engine lights and a rattle noise most often heard at engine start up.
Audi and Volkswagen originally made use of timing chains and moved to an external timing belt through the 80s, 90s and most of the 2000s (now returning to chain drive systems). Unlike the timing chain, the timing belt can be easily inspected and replaced. The cost to replace a timing belt along with all related components (and on most models including a water pump) on most models is $700 to $900–far less than the cost of replacing a timing chain. The down side of the external timing belt is the fact that like all belts, it is a wear item and must be replaced. On average, timing belts should be replaced every 80,000 miles or every 5 years. These should be visually inspected at least once a year or with each service.
Whether you drive a Porsche, Mercedes Benz, BMW, Volkswagen or Audi, It is important to remember that with proper maintenance, today’s German performance vehicles will serve you for many miles and years to come. Trust our experts in Porsche, Mercedes Benz, Volkswagen, Audi, and BMW repair in Austin. If you have any questions, simply come by and see us at German Auto Center. We are conveniently and centrally located at 8215 Research Blvd and we will be happy to assist you.