BMW M5 S38B35

The BMW M5 S38B35 has a reliability score of 47/100, rated "RISKY". Legend tax is real and expensive

The most frequently reported issues are Head and Valve Train Damage, Cam Gear and Timing Chain Wear, Valve Cover and Gasket Oil Leaks, Parts Availability and Escalating Ownership Costs, among others. See the Known Issues section above for symptoms, affected mileage, and repair costs.

Yes, this is a documented issue on the S38B35, typically appearing around 80,000-200,000 km. Forum data references cylinder head scoring from piston debris, with noted damage to valve springs, retainers and cylinder walls. On a 35-40 year old engine, deferred maintenance accelerates this dramatically. Complete head rebuilds are expensive and specialist parts are scarce. Typical repair cost: €1,500-6,000. DIY difficulty: Expert only, full head rebuild territory.

Yes, this is a documented issue on the S38B35, typically appearing around 100,000-180,000 km. The S38B35 cam gears are a known wear and tuning point discussed in the enthusiast community. On ageing examples the timing chain, tensioners and cam gear hardware require inspection and often replacement. Failure to address leads to timing slip and potential engine damage. Typical repair cost: €800-2,500. DIY difficulty: Expert, front cover and cam gear work.

Yes, this is a documented issue on the S38B35, typically appearing around 60,000-150,000 km. The S38B35 valve cover, including the oil fill cap area over the timing chain, is a common source of oil leaks on aged examples. Valve cover gaskets harden and crack over decades. Forum activity around sourcing used valve covers confirms this is a recurring concern. Typical repair cost: €200-600. DIY difficulty: Intermediate.

Yes, this is a documented issue on the S38B35, typically appearing around 0-300,000 km. The S38B35 was produced in very limited numbers for North America only, fitted to the 1987-1988 E24 M6 and the 1988 E28 M5. Forum evidence shows owners actively parting out engines and hunting used components such as valve covers and cam gears. New OEM parts are largely unavailable and specialist sourcing is required for most repairs. Typical repair cost: €500-5,000. DIY difficulty: Expert, sourcing is the real bottleneck.

Yes, this is a documented issue on the S38B35, typically appearing around 0-300,000 km. All examples are now 35-38 years old. Rubber hoses, coolant system components, engine mounts, seals and wiring insulation will be at or beyond service life regardless of mileage. Preventive replacement is mandatory on any purchase. Typical repair cost: €300-1,200. DIY difficulty: Intermediate.

The S38B35 is a genuinely rare and historically significant engine produced for North America for just two model years, which means every surviving example is a collector piece carrying serious financial and mechanical risk. Forum evidence is unambiguous: ownership costs are high, parts are scarce, and even enthusiasts with E28 M5 experience acknowledge these cars are expensive to keep running. Only buy an example with complete service documentation, a clean compression test and evidence of recent timing chain and cooling system work. Budget a minimum of €3,000-5,000 in preventive maintenance immediately after purchase regardless of how good the car appears, and ensure you have access to a specialist BMW mechanic with specific S38 experience before you need one in an emergency.

Before buying, check: Perform a full 6-cylinder compression and leak-down test and reject any engine below 150 psi or with more than 10% cylinder variation; Cold-start the engine and listen for timing chain rattle in the first 10 seconds before oil pressure builds; Inspect the cylinder head and valve cover area with a borescope for scoring, pitting or debris damage as referenced in forum teardowns; Demand a full documented service history including evidence of regular oil changes; unserviced examples carry extreme risk; Check all rubber coolant hoses, engine mounts and wiring loom for age-related cracking and deterioration given the 35+ year age.

There's no fixed mileage limit, it depends on maintenance. The parts worth budgeting for proactively are: Timing chain and tensioner (100,000 km or immediately on purchase), Cam gears (100,000 km), All coolant hoses and thermostat (At purchase regardless of mileage), Valve cover gasket and oil fill cap seal (At purchase or first signs of seeping). Engines that clear these checkpoints with documented maintenance commonly continue well beyond typical ownership periods.

Estimated ownership cost is €6,000-15,000 over 3 years depending on condition and required restoration work, based on known issues and typical service needs.

Owners report real-world fuel consumption of around 9.7 L/100km.

Community-reported real-world usage suggests changing oil every 7,500 km using 10W-40 or 15W-50 high-zinc mineral or semi-synthetic (API SL or earlier spec to protect flat-tappet and cam surfaces), often more conservative than the official service schedule.

The S38B35 is also found in: BMW E28 M5 (1988, North America only), BMW E24 M6 (1987-1988, North America only), Hartge H35-24 E30 conversions (1988, low volume tuner swap, verification_note: exact production numbers unconfirmed).

Legend tax is real and expensive The biggest recurring complaint is Head and Valve Train Damage. Deeply reverent but financially cautious. Enthusiasts celebrate the S38B35 as a motorsport-derived legend while openly acknowledging that running costs, parts scarcity and specialist labour make it a genuinely expensive and demanding engine to own. The common theme is passion overriding practicality.