BMW M3
3.2-litre straight-six with six individual throttle bodies and double VANOS — the last BMW high-revving engine with manual valve clearance adjustment via shims. At idle a dry, slightly rough ticking; from 4,500 rpm the sound screws into a hard, metallic naturally-aspirated wail that only ends at 7,400 rpm. Constructionally a transitional engine: grey cast iron block with aluminium head, forged crankshaft, steel conrods. The oil pump pressure regulation piston is the hidden risk — an aluminium part that seizes in its bore and then delivers low oil pressure at low revs, with bearing damage as the result. A DLC-coated replacement piston solves the problem permanently. VANOS overhaul by 100,000 km at the latest; check valve clearance every 60,000 km; oil changes every 8,000 km with 10W-60. Engines that are never revved suffer — standing damage is more common than running damage on the S50.
Open NA Six — Sound Without a Roof
Roof down, slot a gear, 5,000 rpm — the individual throttle bodies howl right at your ear. The E36 Cabrio is heavier than the Coupe and less rigid, but the acoustic access to the S50B32 is total compensation. The last open M3 with an NA engine and a manual.
Engine Weaknesses 9
Connecting rod bearing shells wear through high revs or a seizing oil pump pressure relief piston. Seasonally stored vehicles (seasonal registration) are particularly at risk. Preventive replacement by 100,000 km at the latest, together with oil pump inspection and crankshaft check.
Symptoms: Knocking from the engine block on a warm engine, dropping oil pressure at idle, metal particles in the oil filter. In the final stage: connecting rod failure.
The pressure relief piston of the oil pump is made of aluminium and tends to seize in its steel bore. The result: insufficient oil pressure at low revs, destroying the connecting rod bearings. A DLC-coated replacement piston is the permanent solution.
Symptoms: No warning initially — oil pressure drops gradually. Knocking only begins once bearing damage has started. Oil pressure check recommended at every oil change.
The solenoid valve sealing rings of the Double VANOS become brittle and cause power loss and poor throttle response. Heavily worn seals damage the housing — at that point only a new or uprated housing helps. Overhaul by 100,000 km at the latest.
Symptoms: Noticeable power loss above 4,000 rpm, poor part-throttle response, rattling on cold start, rough idle.
The S50B32 uses bucket tappets with replaceable shims (2.00–4.25 mm) rather than hydraulic lifters. Valve clearance must be checked and adjusted every 60,000 km. With 24 valves and roughly €16 per shim, materials cost adds up. Neglect leads to power loss and valve damage.
Symptoms: Increasingly loud ticking at idle, power loss in the upper rev range, uneven engine running. If clearance is too tight: valves no longer close fully.
The upper timing chain tensioner has an O-ring that becomes leaky over time, losing oil. Inexpensive preventive replacement during cam cover work. The timing chain itself is long-lived, but the tensioner should be checked at every major engine service.
Symptoms: Light oil seepage at the upper timing chain tensioner; in advanced cases chain rattle on cold start.
The thermostat and plastic expansion tank of the E36 become brittle and fail. Overheating is particularly dangerous in this high-revving straight-six. Replace all plastic cooling system parts preventively at 15+ years — the E36 M3 is now 25–30 years old.
Symptoms: Temperature gauge fluctuates, coolant loss, cracks in the expansion tank, overheating in traffic jams or summer heat.
The six individual throttle bodies drift out of adjustment over time, causing rough idle and poor throttle response. Synchronisation with CO calibration and lambda balance every 60,000 km recommended. Mechanically simple but time-consuming.
Symptoms: Rough idle, engine stumbling at low revs, uneven intake noise audible, slightly increased fuel consumption.
Cam cover gaskets harden with age and start to weep. On the S50B32, due to higher operating temperatures from high-rev use, this happens slightly earlier than on regular straight-six engines. Replace at the same time as a valve clearance service.
Symptoms: Oil smell in engine bay, visible weeping at the cam covers, oil on exhaust manifolds causing light smoke.
The factory rubber engine mounts harden at high mileages and transmit increasing vibrations to the body. Uprated mounts (Powerflex or Motorsport mounts) recommended as an upgrade when replacing.
Symptoms: Noticeable vibrations at idle, judder on sharp throttle application or lift-off, visible cracks in the mount rubber.
Vehicle Weaknesses 4
E36 sills rust at the jack points and at the edges joining the wheel arches. Sunroof drainage routes water directly into the cavities. Severe sill rust is a deal-breaker when buying an E36 M3.
The upper rear trailing arm of the E36 rusts at the spring perches through to perforation — a well-known MOT failure point. Welding repairs are not permitted; replacement is mandatory.
The VANOS system on the S50/S52 engine is extremely failure-prone in the E36 M3. Overhaul costs are substantial. The fault noticeably affects power delivery.
Typical E36 issue: rust blisters at the wheel arches and tailgate. Worn seals promote moisture ingress. A thorough visual inspection before purchase is essential.