The G11 740i with the B58 engine is generally solid, but transmission cooling issues and turbo-related oil consumption can escalate quickly. The list of documented engine internals work suggests some units have seen catastrophic wear or oil starvation failures, though not epidemic-level common.
Transmission Oil Cooler Failure
Common · high severityTypical onset: 60,000-90,000 mi
Symptoms: Transmission overheating warnings on iDrive, Limp mode or delayed shifts when trans temp climbs, Coolant mixing with ATF (milky fluid) in severe cases
Fix: Replace cooler assembly, flush transmission if contamination occurred. 4-6 hours labor depending on access and whether lines need replacement.
Estimated cost: $1,200-2,200
Excessive Oil Consumption / Turbo Oil Feed Issues
Occasional · high severityTypical onset: 70,000-120,000 mi
Symptoms: Burning through a quart every 1,000-2,000 miles, Blue smoke on cold start or under boost, Low oil pressure warnings if neglected, Check engine light for fuel trim or misfire codes
Fix: Root cause varies: clogged turbo oil drain, worn piston rings, or carbon buildup on ring lands. Mild cases respond to catch-can install and frequent oil changes. Severe cases need turbo replacement or short block. Diagnosing properly takes 2-3 hours; short block swap is 20-30 hours.
Estimated cost: $800-1,500 for turbo; $8,000-15,000 for short block
Transmission Mount Deterioration
Common · low severityTypical onset: 50,000-80,000 mi
Symptoms: Clunk or thud on hard acceleration or deceleration, Vibration at idle in Drive, Excessive driveline movement felt through chassis
Fix: Replace transmission mount; straightforward job. 1.5-2 hours labor.
Estimated cost: $400-700
Fuel Filter Clogging / Fuel System Contamination
Occasional · medium severitySymptoms: Rough idle, hesitation, or stumble under load, Long crank or no-start after sitting, Fuel trims way out of spec
Fix: In-tank fuel filter and pump module replacement if clogged or contaminated. Bad fuel or debris intrusion common culprit. 3-4 hours labor for tank drop and module swap.
Estimated cost: $900-1,600
Crankshaft / Main Bearing Failures (Rare but Catastrophic)
Rare · high severityTypical onset: 80,000-150,000 mi
Symptoms: Knocking or tapping noise from lower engine, worsens with RPM, Oil pressure drop, Metal shavings in oil during change, Sudden loss of power, engine seizure in worst cases
Fix: Complete teardown for bearing inspection and crankshaft replacement. Often results in short block or full rebuild. 25-35 hours labor minimum.
Estimated cost: $10,000-18,000
Head Gasket Seepage (Uncommon, but Documented)
Rare · medium severityTypical onset: 100,000+ mi
Symptoms: External coolant weeping at head/block joint, Slight coolant loss with no visible leaks elsewhere, No mixing of fluids or overheating in early stages
Fix: Head gasket replacement on affected bank. Requires head removal, resurface check, and new bolts. 12-16 hours labor per side if both banks done.
Estimated cost: $3,500-6,000 per side
Solid luxury cruiser if maintained obsessively, but oil consumption and trans cooler issues can surprise you with four-figure bills—budget $2k/year in reserves and verify service history before buying.
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.