Getting the timing belt changed on a Volkswagen TDI is the most important maintenance job throughout the life of the vehicle. A correctly replaced belt will ensure many years of continued trouble-free performance. An incorrect replacement job, however, may spell the end of the engine completely. This article outlines what you need to know and need to ask your repair shop
The timing belt ensures that the top half of the engine, or cylinder head, is in step with the bottom half of the engine. An failed belt will cause both halves of the engine to collide, which often results in complete engine destruction. An improperly installed belt may cause rough running, hard starting, poor fuel economy, smokiness or premature failure.
The Volkswagen TDI (turbocharged direct injection) diesel engine has incredible longevity and relatively simple routine maintenance. Replacing the timing belt is the most difficult job a TDI must undergo, but thankfully it only needs replacing every sixty, eight or one-hundred-thousand miles, depending on model and year. Get it done right the first time, and every time after that.
Get the Right Parts
Unfortunately the timing belt replacement kit from VW and most national stores is dangerously incomplete. In addition to the timing belt itself there is a tensioning assembly – responsible with keeping the belt tight and preventing it from jumping – as well as up to three rollers that direct the belt as it links the top and bottom of the engine together. Stick with good name brands such as SKF or INA for rollers, Litens for tensioners. FAG is also a very well regarded bearing manufacturer. Gates, Continental and Dayco are the best belt manufaturers.
In addition to the timing belt, tensioner and roller(s) there is hardware (nuts and bolts) that hold the associated components together. These too much be replaced. Stay with VW OEM hardware – “Home Depot” bolts may damage the aluminum components, rust or fail completely.
A good timing belt kit should come with all these things, including a complete bolt set. Don’t cheap out on quality or bolts – you’ll regret it. We recommend choosing a kit from a recognized TDI or VW specialty shop that includes all the components above.
Find the Right Shop
VW TDIs are interference engines – if the top of the engine, the head, gets out of time with the bottom end, very bad, costly damage will result. Ask the shop first and foremost if they have done a TDI belt before. If they have, ask if they know how to set the “injection timing” and if they have the proper tools to lock the camshaft in place. Many shops use paint marks to keep the engine in place – this is not sufficient. The best shops will have TDI specialty tools such as Metalnerd tool kits and VCDS (also known as VAG-COM) – a shop that has invested in these items understands how important they are to completing the job correctly.
A good place to start your search the Trusted TDI Mechanics List, hosted by TDIClub.