BMW 2.5

The plastic impeller of the M52B25 water pump can slip on the shaft at high mileage. The pump appears to spin normally but no longer circulates coolant. Overheating with cylinder head damage follows quickly.

Symptoms: Coolant temperature rises suddenly on motorway runs, heater output drops, overtemperature warning

Early M52B25 with Nikasil-coated cylinder bores are affected by premature corrosion with sulphur-rich fuel. The coating is attacked and oil consumption rises sharply.

Symptoms: Massively increased oil consumption (>1 litre/1,000 km), blue smoke from the exhaust, measurable compression loss

The DISA variable intake valve breaks at the shaft base or the membrane tears. Fragments can be sucked into the engine and cause catastrophic damage.

Symptoms: Power loss in the lower rev range, rattling or clattering from the intake area, in the worst case engine damage from ingested fragments.

The Behr/Mahle electric coolant thermostat fails prematurely. Failure causes overheating or permanent cold running with increased fuel consumption.

Symptoms: Engine does not reach operating temperature or overheats, poor heater output, increased fuel consumption.

The plastic expansion tank of the M52B25 develops hairline cracks with increasing years of service, which open under heat. Coolant loss can be gradual or sudden.

Symptoms: Coolant level drops regularly, visible cracks on expansion tank, coolant puddle under the car after parking

The O-rings in the M52B25 single-VANOS harden and lose their sealing effect. Oil pressure loss in the VANOS system degrades camshaft adjustment performance.

Symptoms: Judder during warm-up, power loss on a cold engine, irregular idle speed when coolant temperature is below 60°C

The fabric hood tears from years of folding and UV exposure and becomes leaky. Door seals also fail with age. The plastic rear window turns cloudy or develops folds.

Control arms, tie rod ends and ball joints on the front axle wear with higher mileage and are flagged at inspection. Typical issue on all E36-based vehicles.

The barrel bearings at the Z3 rear axle wear at higher mileage and must be replaced. An inexpensive repair that causes no consequential damage if done in time.

The VANOS unit on the six-cylinder engines (M52, M54) is prone to leaks and malfunctions. Worn seals and seized pistons in the VANOS system cause power loss and rough running.