The 2018 750i carries BMW's controversial N63TU2 twin-turbo V8, which has improved over earlier N63 generations but still suffers from fundamental design flaws related to the hot-vee turbo configuration and inadequate crankcase ventilation. Expect major engine work between 60,000-100,000 miles if maintenance wasn't obsessive.
N63 Rod Bearing and Crankshaft Failure
Common · high severityTypical onset: 60,000-100,000 mi
Symptoms: metallic knocking at idle that worsens with RPM, metal shavings in oil during changes, sudden catastrophic engine failure with no warning, low oil pressure warnings
Fix: Full engine-out teardown to replace rod bearings, main bearings, and often crankshaft if journals are scored. If caught early, bearing replacement alone runs 18-24 shop hours. If crank is damaged, add another 8-12 hours plus machine work. Many owners opt for short block replacement instead (25-30 hours).
Estimated cost: $8,000-18,000
Piston Ring Land Failure and Excessive Oil Consumption
Common · high severityTypical onset: 50,000-90,000 mi
Symptoms: burning 1+ quart per 1,000 miles, blue smoke on cold start, carbon buildup on intake valves, misfires under load, failed emissions tests
Fix: Requires complete engine disassembly to replace all pistons and rings. The hot-vee turbo design cooks the rings prematurely. Engine must come out for proper access. 30-40 hours labor plus machine work to hone cylinders. Some shops recommend short block replacement instead given the labor overlap.
Estimated cost: $12,000-22,000
Turbocharger Failure (Both Units)
Occasional · high severityTypical onset: 70,000-110,000 mi
Symptoms: loss of power and boost, screaming/whining noise under acceleration, blue or white smoke from exhaust, oil leaks from turbo seals into exhaust, check engine light with underboost codes
Fix: The hot-vee placement means turbos live in 1,800°F exhaust manifold temps, cooking seals and bearings. Replacing both turbos requires removing intake plenum and half the top engine. 16-22 hours labor. Often discover warped exhaust manifolds during R&R, adding cost.
Estimated cost: $7,000-12,000
Timing Chain and Guide Failure
Occasional · high severityTypical onset: 80,000-120,000 mi
Symptoms: cold-start rattle for 2-3 seconds, check engine light with cam/crank correlation codes, rattling from front of engine that persists, rough idle and poor performance
Fix: N63 uses chains on both banks. Guides wear and chains stretch, especially with extended oil change intervals. Requires front-end disassembly, removing turbos, and extensive timing system work. 18-25 hours labor depending on how much of the valvetrain needs inspection.
Estimated cost: $6,000-10,000
Coolant Transfer Pipe and Thermostat Leaks
Common · medium severityTypical onset: 50,000-90,000 mi
Symptoms: coolant smell in cabin or under hood, visible coolant pooling under intake valley, low coolant warnings, overheating in severe cases
Fix: Plastic coolant pipes running through the valley between cylinder banks crack from heat cycling. Must remove intake plenum for access. Often find multiple pipes and thermostat housings leaking simultaneously. 8-12 hours labor depending on how many components need replacement.
Estimated cost: $2,500-4,500
Valve Stem Seal Leakage
Occasional · medium severityTypical onset: 60,000-100,000 mi
Symptoms: puff of blue smoke on startup after sitting overnight, oil fouling on spark plugs, rough idle when cold, carbon buildup on intake valves
Fix: Heat from hot-vee turbos hardens valve stem seals prematurely. Can sometimes replace seals without head removal using compressed air method (12-16 hours), but many shops pull heads for thorough carbon cleaning while in there (25-30 hours total).
Estimated cost: $4,000-9,000
ZF 8HP Transmission Oil Cooler Leaks
Common · low severityTypical onset: 60,000-100,000 mi
Symptoms: transmission fluid spots under car, low transmission fluid warnings, harsh shifting when fluid is low, transmission overheating on highway drives
Fix: External oil cooler lines and heat exchanger develop leaks at fittings and seams. Fortunately straightforward compared to engine issues: 3-5 hours labor to replace cooler and lines, then fill and flush transmission fluid.
Estimated cost: $1,200-2,200
Only buy if you can afford a $15,000 engine replacement without blinking, or you're prepared to trade it before 70,000 miles — the N63 is fundamentally flawed and even religious maintenance only delays the inevitable.
AI-assisted summary drawn from NHTSA recall data, our labor-times database, and platform knowledge. Not a substitute for a pre-purchase inspection on a specific vehicle.