Timing chain
BMW · 2011-2017. Chain-driven, but early engines are known for plastic timing-chain guides wearing and breaking. Listen for a whine or rattle from the back of the engine on a cold start and ask whether the guides have already been replaced.
Commonly 1 Series, 3 Series, 5 Series, X1, X3, Z4 (20i / 28i) (2011-2017). Engine codes changed through production, so confirm the code on the car in front of you before ordering parts or quoting the job.
The N20 / N26 2.0 turbo petrol used by BMW (2011-2017) runs a timing chain. Chain-driven, but early engines are known for plastic timing-chain guides wearing and breaking. Listen for a whine or rattle from the back of the engine on a cold start and ask whether the guides have already been replaced.
There is no scheduled replacement interval for a chain. Judge it on cold-start noise, fault codes and oil-service history instead.
Expect roughly £1,500-£3,000 at a UK independent garage, depending on whether the water pump and tensioner go in at the same time and how much has to come off to reach the belt. Main-dealer quotes usually sit above that range.
On an interference engine the valves and pistons meet, which usually means a cylinder head at best and a replacement engine at worst. That is why an unproven timing history is a price conversation, not a detail.
Commonly 1 Series, 3 Series, 5 Series, X1, X3, Z4 (20i / 28i) (2011-2017). The list is not exhaustive and engine codes changed through production, so confirm the exact code on the car in front of you before ordering parts or quoting work.
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