BMW 318i e46 N42 engine
R19,500.00
The BMW N42 is a naturally aspirated inline four-cylinder petrol engine produced between 2001 and 2004. It was a landmark design for BMW, being the first to feature Valvetronic technology, which eliminates the traditional throttle body by varying intake valve lift.
Technical Specifications
The N42 replaced the aging M43 and was built with an aluminum block and head, featuring a DOHC 16-valve configuration.
| Version | Displacement | Power Output | Torque | Primary Models |
|---|---|---|---|---|
| N42B18 | 1.8L (1,796 cc) | 115 hp @ 5,500 rpm | 175 Nm @ 3,750 rpm | E46 316i / 316ti |
| N42B20 | 2.0L (1,995 cc) | 143 hp @ 6,000 rpm | 200 Nm @ 3,750 rpm | E46 318i / 318Ci / 318ti |
Key Technologies
- Valvetronic: Electronically adjusts valve lift from nearly zero to fully open to reduce pumping losses and improve fuel efficiency.
- Double-VANOS: Variable valve timing on both intake and exhaust camshafts for better low-end torque.
- DISA Manifold: A variable-length intake system that optimizes airflow across the rev range.
- Twin-Balancing Shafts: Integrated to reduce vibrations and ensure smoother operation.
Common Reliability Issues
While innovative, the N42’s increased complexity led to several well-documented maintenance challenges:
- Timing Chain System: The plastic guides and tensioners are prone to wear, often causing a “rattling” sound on cold starts; failure can lead to severe engine damage.
- Oil Consumption: Frequently caused by hardened valve stem seals or PCV system (CCV) failures, leading to blue smoke or high oil usage.
- Eccentric Shaft Sensor: A critical component for Valvetronic that often fails due to oil contamination, resulting in rough idles or limp mode.
- Cooling System: Like many BMWs of this era, the plastic water pump, thermostat housing, and expansion tank are known to crack after roughly 80,000–100,000 km.
Successor
In 2004, the N42 was succeeded by the N46 engine, which shared the same core architecture but featured an updated ECU, a revised intake manifold, and improved Valvetronic mechanics.