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  • Writer's picturePonyboy

Timing Chain Stretch and Hop—An Exercise to Avoid

Over time, a timing chain will wear and can fail. It stretches and will get so loose that it will physically hop over the timing gears, exactly like a bicycle chain that gets too loose then hops over the gear(s) and falls off. When a timing chain hops over the timing gears, it causes the engine to be out of time.

A common cause of timing chain stretch is wear via time and mileage. The chain goes around the gears of the crankshaft at the bottom of the engine, constantly pulling on the gears of the camshaft at the top of the engine. The chain goes around and around countless times under load and is constantly pulling to keep the engine in sync. This constant pulling over time literally, literally stretches the chain.


The chain tensioner, or the guides that are connected to the timing chain, may wear out as well and can cause the timing chain to fail completely.


Another common cause is lack of proper maintenance. Regular maintenance and regular oil changes, using the correct oil, every 5,000 miles is the best way to combat timing chain stretch and failure.


Timing chain stretch is a common issue in Volkswagens and Audis with newer 4 cylinder turbo engines, 2008 and up (V6 and V8 engines do not suffer from timing chain stretch). We start to watch for stretch at about 70,000 miles and recommend immediate replacement of chains that measure five degrees or more stretch because that is when the chain can begin to hop over the gears and when that happens there is a risk of bending valves and causing catastrophic engine damage.

The difference between the new chain on the right and the stretched chain on the left, which had hopped time prior to the vehicle owner towing it in, shows just how significant a typical timing chain can stretch.


Upon recognizing that the vehicle not only took longer than normal to start, but also drove sluggishly, the vehicle owner's daughter who was driving the vehicle at the time, decided, very smartly, not to continue to drive it, and instead the vehicle was towed in thus preventing further damage.


When we ran diagnostics we found that the timing was indeed off and that the chain had hopped -39.99 degrees.

Installed, the new timing chain measures 0.09 degrees, which is normal. When it's brand new, it should be close to zero, but will not be perfectly zero due to manufacturing tolerances.


It is important to have your vehicle serviced regularly for oil changes—every 5,000 miles and with the correct oil. Doing so is the best preventive maintenance of timing chain stretch and hop. And having your vehicle regularly serviced by a specialist, competent in timing chain wear, who will regularly monitor your timing chain for stretch, and replace it before it stretches too much and hops causing major damage to the engine, is necessary.

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