BMW 523i Timing Chain Rattle: Worn Cam Gear Found and Replaced

The owner had a BMW 523i making a rattle from the engine. The noise seemed to come from the front of the engine, around the timing cover, and it was there both at idle and while driving. The car was lowered and had a body kit, so rather than risk it on a normal tow, we arranged the right kind of towing to bring it in safely.

A rattle from the timing area is one of those noises you do not want to leave. The timing drive keeps the top and bottom of the engine in sync. If something in there is wearing, the sensible move is to look before it turns into a much bigger and more expensive problem.

Our chief mechanic listened to the engine first and placed the noise at the timing, not lower down in the block. A timing rattle has a particular sound and location, and pinning that down before opening anything saves time and money.

To confirm it, we opened the timing cover and inspected the chain, the sprockets and the cam gear. The cam gear was worn, which was the source of the rattle. We took photos and a video of the exposed timing components and the worn gear, and showed the owner exactly what we had found before quoting. Seeing the worn gear made the repair easy to understand.

Once the owner approved, we replaced the worn timing parts properly rather than patching the noise.

• Replaced the timing set and the worn cam gear with original BMW parts.
• Reassembled the timing drive to the correct timing and tension.
• Carried out servicing while the car was with us.
• Road tested the car to confirm the rattle was gone before handover.

We used original parts here, which the owner agreed to. The timing set and cam gear with labour came to $2,580 before GST. After the work the timing was quiet and the engine ran smoothly, which we confirmed on the road test before the car went back to the owner.

What a timing chain and cam gear repair costs depends on which timing parts are worn and whether you use original or OEM parts. This job was $2,580 before GST for the timing set and cam gear with original parts and labour.

What moves the price is how much of the timing drive needs replacing. A single worn cam gear with the chain still good sits at the lower end. If the chain, guides, tensioner and VANOS parts are all worn, the job grows. This is why we open and inspect the timing first, then quote for exactly what is worn, rather than replacing everything by default.

This BMW 523i (Timing chain and cam gear repair) was handled at 1 Car Service, an independent workshop in Sin Ming AutoCity, Singapore. For BMW, we use dealer-level ISTA diagnostics. We hold a 4.9★ rating from 1,775+ Google reviews.