BMW M4 GTS
2,979 cc twin-turbo straight-six with closed-deck block and two mono-scroll turbochargers — BMW's first M engine with forced induction since the legendary M106. The block is significantly stiffer than the open N55 block and can handle cylinder pressures beyond 20 bar. Forged 42CrMoS4 steel crankshaft, Grafal-coated Mahle pistons in liner-free cylinders with LDS arc-spray coating — no liner, no sleeve. The sound divides the M community: under full throttle a deep, aggressive roar with turbo whistle on boost build-up, but miles away from the metallic naturally-aspirated shriek of the S65. In return the S55 delivers 550 Nm from 2,500 rpm that outpaces the S65 to 5,000 rpm. The hidden risk: the two-piece crank hub. On cars built before 03/2017 it can detach without warning — valve timing jumps, pistons hit valves, catastrophic engine failure. Affects 2–3% of all S55, but when it happens the engine is finished. Retrofitting a one-piece crank hub (€1,500–3,000) is the most important action. Second issue: plastic charge pipes burst under high boost — water from the intercooler can enter the intake and at 85,000 km cause a con rod failure. Aluminium upgrades are mandatory. Oil changes every 8,000 km with 0W-40; fit an oil cooler stone guard; check con rod bearings every 50,000–70,000 km. Those who observe these three points have an engine that lasts 200,000 km while tolerating 600+ hp via software.
500 hp, water injection, roll cage — 700 units
The M4 GTS is BMW's first production car with water injection: 5 litres of distilled water cool the intake air by 25°C, boost pressure rises to 1.49 bar — 500 hp and 600 Nm. Plus KW Clubsport suspension, adjustable in compression and rebound, roll cage instead of rear bench, polycarbonate rear window. The steering is razor-sharp, the rear on Cup2 tyres almost too forgiving for a car without an ESP button. 700 units, all spoken for on the spot — faster around the Nordschleife than a 997 GT3.
Engine Weaknesses 10
Known issue on M3 F80 and M4 F82. Connecting rod bearings wear prematurely; preventive replacement every 50,000–80,000 km is widely recommended.
Symptoms: Knocking from the engine block, metallic particles in the oil, oil pressure warning
The multi-piece crankshaft hub is secured only by friction and can slip under load. Vehicles built before production date 3/2017 are particularly affected. Even minimal rotation misaligns valve timing — valve-to-piston contact and total engine loss are possible.
Symptoms: Usually no warning. Early signs: EML 'drivetrain error', rough idle, misfires, power loss under high load. Worst case: immediate total engine failure at high revs.
The exposed oil cooler (tube-fin design) hangs unprotected in front of the cooling pack and is frequently damaged by stone impact. Even small holes lead to sudden total oil loss and imminent engine damage.
Symptoms: Sudden oil pressure warning; visible oil trail under the vehicle; oil smell; often no gradual build-up — failure without warning
With axial bearing wear on a mono-scroll turbocharger, oil consumption can rise to 1 litre per 500 km. Cause: failed turbo drawing oil past the shaft seal. Regular oil level checks are essential.
Symptoms: Rapidly increasing oil consumption, bluish smoke under acceleration or at idle, power drop, whining turbo noises.
The plastic end tanks of the water-cooled intercooler become porous and allow coolant to escape. In the worst case water enters the intake tract — hydro-lock and engine damage are possible. Mainly affects 2016–2019. Aluminium upgrade recommended.
Symptoms: Warning 'charge air temperature high' or 'cooling system low'; coolant loss without visible external leak; misfires; white smoke
The standard plastic charge pipes between turbocharger and intercooler split at the flanges under boost pressure. Stock vehicles are rarely affected — the risk increases considerably with tuning.
Symptoms: Loud hissing on boost build-up; severe power loss; limp mode; fault codes P00BD/P00BF (mass air meter reading too high)
The mechanical water pump of the S55 wears under the high thermal demands of the twin-turbo engine. Thermostat and water pump should be replaced as a pair. A failed thermostat prevents coolant circulation — overheating at full load on a motorway can occur within minutes.
Symptoms: Coolant temperature fluctuates unusually, coolant warning under high load, faint whistling from engine bay, coolant loss without visible leak.
Wastegate flaps can rattle more on tuned S55 engines. Less common than on the N54 at stock power levels.
Symptoms: Metallic rattling on load changes, clattering on throttle application
The S55 cam cover gasket hardens through constant heat cycling and begins to weep from around 80,000 km. Oil drips onto the belt drive — a failed belt can cause consequential damage. Replace the spark plug tube seals at the same time.
Symptoms: Oil smell in engine bay after a motorway run, visible oil on the side of the cylinder head, oil patch on the underbody panel. In advanced cases light smoke.
The oil filter housing gasket leaks from 50,000–80,000 km — a persistent issue on all modern BMW six-cylinders. Oil pools beneath the housing and drips onto the undertray. The gasket itself costs under €30 but access requires removing the intake manifold.
Symptoms: Oil patch under the engine on the driver's side, oil smell on a hot engine, visible oil trace at the filter housing during an oil change.
Vehicle Weaknesses 6
Recall 18V713000: connection between propshaft and flange can fail. M4 Convertibles also affected (MY 2017, 269 units). Free propshaft replacement.
BMW uses only one rubber bushing instead of two attachment points on the subframe. Under torque fluctuations the bushing tears. Powerflex dual-mount solution as a common fix.
Factory clear coat on the CFRP roof starts peeling after 3–5 years. UV radiation destroys clear coat adhesion. M4 GTS particularly often affected.
EDC dampers lose function through oil leakage or electrical defect. Fault often occurs shortly after warranty expiry. Bilstein Damptronic as a cheaper alternative.
Coloured trim strip on the Alcantara steering wheel fades from UV and hand contact at around 15,000 km. No effective factory protection. GTS wheels with an inlaid strip are considerably more robust.
Stock M compound brake pads squeal noticeably in cold and light braking. High dust generation leads to wheel contamination.
