BMW 2.5i
Balanced six-cylinder with 192 hp and silky-smooth running. Cooling system components (water pump, thermostat, expansion tank) are the most common wear items.
The all-rounder among naturally aspirated engines
192 hp, smooth revving, relaxed everyday driving yet thrilling on winding roads. The 2.5i is the perfect balance — not too little, not too much, always six-cylinder sound.
Engine Weaknesses 6
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 quickly, poor heater output.
The plastic membrane in the crankcase ventilation system typically tears at 120,000–150,000 km. Result: air leaks, oil enters the intake tract, increased oil consumption and rough running.
Symptoms: Rough idle; slight exhaust smoke; increased oil consumption; "puff" when opening the oil filler cap; air-leak fault codes
The expansion tank, thermostat housing, and water pump impeller — all plastic — become brittle from around 100,000 km. Sudden coolant loss leading to overheating is possible.
Symptoms: Coolant loss with no visible source; fluctuating temperature gauge; steam from the engine bay; expansion tank can burst without warning
The rectangular gasket between the oil filter housing and the engine block fails regularly. BMW part number 11421719855 — aftermarket gaskets tend to have a shorter service life.
Symptoms: Oil seeping below the oil filter, oil smell when engine is hot.
The rubber seals in the double-VANOS unit wear from around 100,000 km. Reduced torque in the lower rev range and a slight increase in fuel consumption are typical results.
Symptoms: Noticeable torque loss below 3,000 rpm; hesitation when pulling away; occasional VANOS fault codes (P1519, P1520); engine noise on cold start
Vehicle Weaknesses 7
The hydraulic pump for the Z4 E85 hood is mounted in a poorly protected position. Blocked drains allow water ingress; the pump corrodes and fails. Replacement is labour-intensive and expensive.
The electric power steering on the Z4 E85 occasionally fails — particularly on short-trip drivers as the battery becomes too weak. Steering angle sensor faults and column defects also occur.
The N46B20 four-cylinder in the 2.0i Z4 E85 suffers from premature timing chain wear due to a weak chain tensioner. Neglected oil maintenance causes the chain to elongate and can lead to engine damage.
Water enters through leaking tail lights or the boot vent. The expansion rivets on the tail lights become porous, seals age and allow moisture in. Can lead to short circuits and mould.
Ignition coil failures are a known issue on the Z4 E85, particularly at higher mileage. Oil from the valve cover gasket into the spark plug tubes is often a contributing factor. Multiple coils can fail in succession.
The sporty suspension setup on the Z4 E85 leads to above-average tyre wear, especially at the rear. Rear tyres can be at the wear limit after just 25,000 km. Broken springs have also been reported.
On the E85 Z4, the rain sensor and window regulator motors fail more often than usual. The rain sensor triggers in sunshine; windows move jerkily or not at all — both are age-related symptoms.
Reports & Tests
1161 owner complaints filed with NHTSA (2002–2008). Most reported: Steering (965), Airbags (86), Electrical (52).