BMW Z4 M
3.2 litres, six individual throttle bodies, 343 hp at 7,900 rpm — 104 hp per litre without forced induction, International Engine of the Year 2001. Below 5,000 rpm surprisingly restrained; then the throttle bodies open and the intake tract screams. At 8,000 rpm a high-pitched wail through six separate intake trumpets that no turbo engine can replicate. VANOS rattle between 1,800–2,200 rpm on cold start is not an alarm sign but a wear indicator of the helical gears — repair from €800. Have con rod bearing shells replaced preventively from 80,000 km; avoid pre-facelift (before 2004) with its more vulnerable oil pump. Check the head gasket between cylinders 5 and 6. Oil changes at most every 10,000 km, Castrol TWS 10W60 or Mobil 1 5W50 — the S54 takes neglect personally. Warm-up below 3,000 rpm until operating temperature is not a tip, it is a requirement.
S54 in the Long Roadster — 343 hp, No ESP, No Net
The Z4 M Roadster puts the S54 in a longer wheelbase than the Z3 M — more predictable, but no less exciting. Without ESP the Z4 M demands full respect in the wet: 343 hp to the rear axle, no electronic safety net, plus steering that transmits every surface imperfection. In the dry, one of the finest manual driving experiences BMW ever created. Sounds even better open — the ITB intake mixes with the exhaust into a soundscape that raises goosebumps at 7,000 rpm.
Engine Weaknesses 9
Connecting rod bearings wear through excessively long oil change intervals (BMW recommended 15,000 km — too long). Early build dates 02/2001–05/2003 had non-spec bearing shells; BMW issued a recall. Preventive replacement by 100,000 km is strongly recommended.
Symptoms: Metallic glitter at the drain plug, copper particles in the oil filter at oil changes. In advanced stages: knocking from the bottom of the engine, oil pressure drop. Sometimes no warning before total engine failure.
The original aluminium pressure relief piston of the S54 oil pump wears in its guide bore. Oil pressure at operating temperature drops below 0.5 bar at idle — bearing damage follows. A DLC steel piston is the permanent solution.
Symptoms: Oil pressure warning on warm engine at idle, especially after motorway runs. Engine ticking. Sometimes no warning until bearing damage occurs.
The S54 uses mechanical bucket tappets with shim discs — valve clearance must be checked every 40,000–48,000 km. Neglected shims can fall out and damage rockers, camshafts and valves. Documented from 47,000 km with poor maintenance.
Symptoms: Loud ticking on warm and cold engine, pronounced power loss above 5,000 rpm, misfires in extreme cases.
O-rings in the sealing plate of the Double VANOS harden and start to leak; oil pressure in the VANOS system collapses. The variable camshaft phasers no longer work correctly; power and torque delivery suffer noticeably.
Symptoms: Rough idle, rattling on cold start, noticeable power drop below 4,000 rpm, engine sounds like a diesel. Fault memory shows camshaft phaser errors.
The inlet camshaft sensor of the S54, located beneath the individual throttle bodies, delivers faulty signals in operation. Installation with a genuine BMW sensor only is recommended — aftermarket parts often do not resolve the problem permanently.
Symptoms: Engine stalls at idle or when declutching; engine warning light illuminates; fault memory shows 'inlet camshaft sensor — incorrect values'. Sometimes only when the engine is warm.
Like all E46 engines, the S54 uses a plastic thermostat and plastic water pump that fail with age. Especially on the sporting S54 with high operating temperatures, preventive replacement is advisable.
Symptoms: Overheating warning, coolant loss without visible leak, engine fails to reach operating temperature (thermostat stuck open), temperature fluctuations while driving.
The crankcase ventilation valve of the S54 clogs through oil sludge deposits and freezing in cold weather. Crankcase overpressure pushes oil into the intake tract. Often the first sign of neglected maintenance.
Symptoms: Increased oil consumption (up to 0.5 l/month); blue exhaust smoke; oil film on spark plugs; whistling noise from the engine
The thermal oil level sensor (BMW 12617508003) on the S54 gives false readings: the oil warning light illuminates on start-up and goes out again despite the oil level being correct. Typical ageing problem on all E46 M3s.
Symptoms: Oil warning light briefly illuminates on start-up and goes out; oil temperature display stays at 0; oil warning light permanently on despite correct oil level.
The S54 cam cover gasket hardens with age and leaks oil towards the spark plug tubes. Oil on the spark plugs causes misfires. Typical maintenance issue on vehicles from 80,000 km.
Symptoms: Oil smell in engine bay, oil film under the cam cover, misfires from oil-soaked spark plugs, blue smoke after standing.
Vehicle Weaknesses 6
The high-revving S54 in the Z4 M shares the well-known con rod bearing shell weakness with the E46 M3. Metal debris in the oil is an early warning sign. Short oil change intervals are essential.
The crossmember under the dashboard on the Z4 E85 is prone to severe corrosion. The rear axle also rusts without regular attention. Inspection every six months is recommended.
The rear differential of the Z4 M E85 is known for bearing wear that manifests as a howling noise between 2,800–3,200 rpm.
The VANOS unit in the S54 of the Z4 M suffers from hardening O-rings. Camshaft bearing clearances increase. The timing chain guide rail breaks around 140,000–150,000 km.
The fabric roof on the Z4 M E85 suffers from hydraulic pump failures from water accumulation and sensor failures. The hydraulic system is only available as a complete unit.
Due to the sporty character of the Z4 M and the high-revving S54 engine, brake pads and discs wear above-average quickly. Rear tyres can be at the wear limit after just 25,000 km.