Timing Chain Failures on Eurovans: Word of Warning!

Before you sign off on a "timing chain failure" repair, take the time to read this informative article.

Oftentimes, a diagnosed "timing chain failure" is not actually that at all—and it is not caused by timing chain "stretch." Rather, it is the timing chain system which fails.

What is commonly referred to as timing chain "stretch" is just the tiny bit of wear that occurs naturally within each link of any chain. When added up over all the links, the chain ends up a tad bit longer—which is why people say that it has "stretched." The timing chain system in an engine includes guides and a tensioner that are designed to accommodate the anticipated chain wear. This chain wear is not typically what causes the system to fail; it is usually the system that fails. Specifically, a combination of sprockets and/or chain guides and/or tensioner and/or—in the case of 2001-03 models with 24 valves and variable timing—variable timing components fails. (For more information on a problem specific to the VR6 timing chain, please read this article.) This is usually due to poor maintenance: not changing the oil frequently enough or not using high-quality lubricants. It should be noted that if you were to follow the officially-recommended engine oil service schedule in the VW manual, you would likely end up with a timing chain system failure well before the rest of engine wears out. It seems that, as manufacturers competed to produce "lower maintenance" vehicles, they simply increased the recommended time/mileage maintenance figures without actually making any engineering changes—knowing full well that the parts would last just long enough to be out of warranty when a failure did occur. The bean counters and advertising executives strike again!

When a system failure does occur, it often just throws a check engine light (CEL) code, and the engine runs a little funny or won't pass smog. But what can also happen is that one or more of the valves crashes against one or more of the pistons. In order to get to the chain system on a VR6 engine, the transaxle must be removed—the chains are located toward the rear of the engine, near the flywheel. Herein lies the rub! Once the transaxle is removed, there is no way to crank the engine over, because the starter is mounted on the transaxle. We have heard horror stories of people paying a shop for 17 hours of labor to remove the transaxle, replace all the chain components, and put it all back together... only to find out there is more internal damage inside the engine that went unchecked!

Thus, before you approve a timing chain replacement, some effort should be spent to determine if the engine is still copasetic. If it still runs, a leak-down test should help reveal if everything is okay. If it does not run (complete failure), it may require the use of a bore scope to look inside through the spark plug holes to see if there has been any contact between the valve(s) and piston(s). If the engine is not otherwise healthy, it probably makes more sense to install a new engine long block, which will include new chains. 

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