BMW F30 N20 engine timing chain and cold-start noises
F30 320i N20 whines or rattles when cold, what is the cause?
The N20's timing chain and oil pump chain can stretch and the sprocket teeth can wear. It is heard as a whine or rattle when cold. After replacing the chains and sprockets the noise has usually gone, but not always, if the cause is elsewhere.
Does the timing chain have to be replaced at the same time as the oil pump chain?
Yes, it is advisable to replace both at once so you are not left guessing which one caused the noise. Stretch of 1-2 cm has been found in replaced chains.
Is a chattering noise on a cold start normal on an F30 320i?
The chattering and droning noise typical of a direct-injection petrol engine during the first 10-20 seconds after a cold start is normal and evens out as the engine warms up. A constant rattle, or one heard under load, should be investigated.
How can N20 timing chain wear be limited?
Oil change intervals that are too long are considered the biggest cause of timing-end problems, so shortening the interval helps. Do not load the engine until the oil has warmed up.