Engines
BMW N20 timing chain problems: symptoms, checks and what to do
The N20 is a strong, efficient engine, but early units have a known weakness in the timing chain guides. Caught early, it is a planned repair. Ignored, it can destroy the engine.
Which cars have the N20?
The N20 2.0-litre turbo petrol was fitted to many BMWs from about 2011 to 2017, including the F30 320i and 328i, F10 520i and 528i, E84 and F48-era X1 xDrive20i/28i, F25 X3 xDrive20i/28i and the F22 220i. Many of these are on Nairobi roads as Japanese and UK imports.
The problem
On earlier N20 engines, the plastic guides for the timing chain can wear and break. When that happens, the chain can jump teeth and the valves can hit the pistons. The timing chain on the N20 sits at the back of the engine, next to the gearbox, which makes it a workshop job rather than a roadside repair.
Symptoms to listen for
- A whining or rattling noise, often loudest on a cold start or around 1,500 to 2,500 rpm.
- Camshaft or crankshaft correlation faults in the fault memory.
- Rough running after a cold start.
- Pieces of plastic in the oil, found during a service.
Do not guess
A loose heat shield or a worn belt tensioner can make a similar noise. We check the fault memory with ISTA, listen with the car cold, and inspect before anything is opened. If it is the chain, we explain why it should be done soon and what the full job includes.
What the repair involves
A proper repair replaces the timing chain, guides and tensioner with the latest new OEM parts, and usually the oil pump drive chain while the engine is apart. We do this at our workshop. Doing half the job to save money is a false saving on this engine.
How to lower your risk
Change the oil on time with the correct BMW-approved specification. Old, thin oil wears chain guides faster. If you are buying an N20 car, a pre-purchase inspection should include a cold-start listen.