The timing chain synchronises the crankshaft and camshafts so that valves open and close at exactly the right point in each engine cycle. When it wears, the consequences are serious. At worst, the chain jumps a tooth on the sprocket, the timing is thrown out, and valves collide with pistons. On most modern engines that means bent valves at minimum and a destroyed cylinder head in the worst case. At KITH Cars Garage in Hackbridge, timing chain replacement is one of the repairs we carry out most often.
The noise to listen for is a metallic rattle or chatter from the engine on cold start. It typically shows up in the first few seconds, before oil pressure builds and the tensioner pumps up properly. As the engine warms the noise often fades. Many customers assume this means the problem has gone away. It has not. The chain is worn and the window for a clean repair is getting shorter.
We always replace the complete kit. Chain, tensioner, all plastic chain guides and the sprockets. A chain on its own costs less but it will not last. The guides wear in contact with the chain. Fitting new against old means rapid re-wear, and you are back to the same problem within a year. We use Iwis, Febi Bilstein or equivalent quality kits depending on the engine.
The BMW N47 diesel is the most common timing chain job we deal with. It was fitted to the 1 Series, 3 Series, 5 Series, X1 and X3 from 2007 to 2015, and it has a well-documented weakness. The chain sits at the back of the engine, next to the gearbox. That is a more involved job than a front-mounted chain and the labour time reflects it. We have done this repair many times and know the procedure thoroughly.
Every job includes a fresh engine oil and filter change. Oil quality is directly connected to timing chain life. Degraded oil with low viscosity at operating temperature accelerates wear on the chain and guides significantly. We also scan the ECU before and after the job to confirm the fault codes and verify the repair.
Leaving a worn timing chain too long is an expensive decision. The repair cost jumps dramatically once the chain has jumped a tooth. A straightforward chain job becomes a head rebuild or worse. If you have heard any cold-start rattle, call 020 4629 9469 for a no-obligation diagnostic and written quote.
