This thread is for those of us with the N42 or N46 four-cylinder petrol engines found in UK models like the E46 316i and 318i (typically post-2001/facelift). While these engines can be efficient, they have a reputation for some specific issues.
Let's pool our knowledge on:
- Timing Chain & Tensioner Problems: The dreaded timing chain rattle or failure. What are the warning signs? Is preventative replacement of the chain, guides, and tensioner a good idea? Approximate costs for this job at a UK independent specialist vs. DIY?
- Valvetronic System Issues: Eccentric shaft sensor failure, Valvetronic motor problems. Symptoms (e.g., rough idle, misfires, reduced power, EML on)? Diagnosis and repair tips.
- Oil Leaks: These engines are notorious for leaks! Common culprits: vacuum pump seal, rocker cover gasket, oil filter housing gasket, sump gasket, oil pressure switch, crankshaft seals. Share your experiences and fixes.
- Misfires & Ignition Coils: Causes of misfires on the N42/N46? Reliability of ignition coils?
- Oil Consumption: Do these engines also suffer from high oil consumption like some M54s? Valve stem seals?
- CCV System: Is the CCV system as problematic as on the M54?
- Your experiences with these N42/N46 engine issues in the UK.
- Recommended independent BMW specialists in the UK who are knowledgeable about N42/N46 engines.
- DIY guides or tips for tackling any of these problems.
- Reliable UK parts suppliers for N42/N46 specific components.
- Advice on what to check when buying a used E46 316i/318i with one of these engines.
Please specify your model (316i/318i), engine (N42/N46), and year.
