BMW/S38B35
BMW · Naturally aspirated

S38B35

M5·E28·19861988·3,795 cc

"Just couldn't afford to keep it running. About a million things."

RISKY
62/ 100
"Legend tax is real and expensive"
335
Max HP
400
Torque Nm
7,500
Oil interval km
0
Recalls
5
Known issues
Known Issues
Head and Valve Train Damage€1,500-6,000 · 80,000-200,000 kmCRITICAL

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.

Compression loss on one or more cylinders
Ticking or rattling from valve train
Oil contamination or milky residue
Rough idle and misfires
DIY: Expert
Cam Gear and Timing Chain Wear€800-2,500 · 100,000-180,000 kmHIGH

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.

Rattling on cold start from timing chain area
Rough running at idle
Cam position errors if later diagnostics fitted
Loss of power
DIY: Expert
Valve Cover and Gasket Oil Leaks€200-600 · 60,000-150,000 kmMODERATE

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.

Oil smell from engine bay
Visible oil seepage around valve cover perimeter
Smoke from hot oil on exhaust manifold
DIY: Intermediate
Parts Availability and Escalating Ownership Costs€500-5,000 · 0-300,000 kmMODERATE

The S38B35 was produced in very limited numbers for North America only in 1987-1988. 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.

Extended downtime waiting for parts
Premium pricing on all specialist labour
Difficulty finding qualified mechanics
DIY: Expert
General Age-Related Cooling and Rubber Component Deterioration€300-1,200 · 0-300,000 kmLOW

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.

Coolant seeps or overheating
Cracked or swollen coolant hoses
Rough engine vibration from degraded mounts
Electrical gremlins from brittle wiring
DIY: Intermediate
Advertisement
Buying Checklist
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
Verify parts availability and get quotes for timing chain kit, cam gears and head gasket set before committing to purchase
Service Reality
Community oil interval7,500 km
Oil specification10W-40 or 15W-50 high-zinc mineral or semi-synthetic (API SL or earlier spec to protect flat-tappet and cam surfaces)
Est. ownership cost (2yr)€2,000-5,000 per year depending on condition and required restoration work
Real mix fuel consumptionNo data
Also Found In
BMW E28 M5 (1987-1988 North America)BMW E24 M6 (1987-1988 North America)Hartge H35-24 E30 conversions (1988)
Buying Advice

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.

Advertisement