The N42 and N46 engine fitted to many different BMW models can be particularly prone to timing chain problems.
The usual culprit is broken guides, caused by the original timing chain tensioner being too short thus allowing the chain to be slack, and rubbing or clattering against the guides. The revised tensioner is longer so keeps the chain tighter, avoiding issues.
Common symptoms are a noisy engine at the front particularly from cold start, misfiring, and error codes for camshaft sensors when the sensors are ok.
Most N42 engines have had a chain by now, but the later N46 still suffers problems with chains, so here’s a brief description of the job being done for anyone that may be interested.
With rocker cover already removed, and camshaft/vanos units removed. Timing chain and guides remove as one unit in the cassette.
As the leading BMW specialist in essex, Power Developments are here to help.
New timing chain and guides. You’ll need to swap over your crank toothed pulley.
Timing tools fitted. Crank must be locked at TDC cylinder 1, the tool for this is in the timing kit.