Metallic sound from the valve train in BMW – what is the reason and how to fix it?

BMW driver’s question

I imported a car in June 2012 from Belgium with 146,000 kilometers and from the beginning from the rear of the engine where the timing gear is located, a metallic, cyclic sound was heard from the outside – as if rubbing metal against metal. When the engine was cold, the sound was louder. With the engine warmed up – it was a little quieter. Inside the car nothing was audible. Dynamics ok, combustion at 4.9 l ON on the road.

I reached the mileage of 149,500 km. The diagnosis at BMW ASO was: “timing set to be replaced, but we do not give a guarantee that after replacement the noise will not return – it is such a beauty of these engines”. We service cars in which the problem occurred after a mileage of, for example, 20,000 km and after replacement returned in another 2,000 km. We also service cars in which customers drive without replacement “with rattling” after 200,000-300,000 km.

My question is: should I be concerned about this noise or “like” it and drive with it?

The problem concerned the BMW e 90 318D 2008r 105KW N47, but it happens in other models as well.

Response from BM Cars service

The answer to your question can be only one – one must not “get used to” or “like” the noises coming from the valve train.

The problem you described actually affects very many users of the E90/E91 model with the N47 engine , and is usually related to excessive wear or loosening of the timing chain. For most ASO stations, the diagnosis is only one, just as you described – replacement of the entire timing chain.

We, however, suggest multi-step repairs, which are much cheaper and in very many cases extremely effective. It is best to start by replacing the timing chain tensioner and checking the type of engine oil used in your engine.

In the vast majority of vehicles with the above-described malfunction, replacing the hydraulic tensioner and oil alone – with the recommended Castrol 5W/30– has helped. If the chain tension is too high, i.e. the operation with the existing noises was too long, replacing the tensioner alone will not help. It is then necessary to replace both chains complete with sprockets. Due to the location of the timing gear, the repair is time-consuming and relatively expensive.

When done correctly, it solves the problem for the next 200,000 km (or more) – provided that the correct consumables and timely maintenance are used.

Returning to your question – it is necessary to repair as soon as possible. Continued operation of the engine with the described noises threatens to seriously damage it. Repair then will be uneconomical.

The technical action, under which authorized BMW service centers repaired the defect in this model for free, was completed in December 2015.

We invite you to take advantage of our service.

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