BMW E60 M57 engine timing chain breaking
Why does the timing chain of the E60's M57N engine break?
A chain breaking is rare. The most typical cause is the rocker arm bearing disintegrating: a loose roller or needle gets caught between the chain and the sprocket. This is practically the only common way the chain breaks on this engine.
What does a timing chain breaking damage?
The rocker arm can break, the valves bend and hit the pistons, and the camshafts twist. The engine stops suddenly and does not pull. Sometimes the engine can be repaired by machining the head and renewing the timing drive; the valves should be replaced.
Does the timing chain have to be replaced after a certain mileage?
BMW has no official mileage interval for replacing the chain. The chains that have broken have usually been on cars with over 300,000 km.
Does replacing the high-pressure pump upset the timing chain timing?
No, when the correct removal tool and the gear holding tool are used. Replacing the pump does not require taking the front end apart.