The 1997 Q45 delivers V8 luxury and rear-drive dynamics, but the VH41DE engine is notorious for catastrophic piston/ring failures due to nickel-silicon bore coating wear, and transmission oil coolers fail internally causing cross-contamination that destroys the transmission.
Nikasil Cylinder Bore Coating Failure Leading to Engine Rebuild
Common · high severityTypical onset: 80,000-150,000 mi
Symptoms: excessive blue smoke on cold start, heavy oil consumption (1+ qt per 1,000 mi), loss of compression, misfires under load, metallic rattling from engine
Fix: The VH41DE used nickel-silicon (Nikasil) bore coating that degrades with high-sulfur fuel and normal wear. Pistons score the bores, rings lose seal. Full rebuild with sleeved cylinders, new pistons/rings, bearings, gaskets required—25-35 hours labor. Many shops recommend replacement short blocks or used engines instead.
Estimated cost: $4,500-8,000
Transmission Oil Cooler Internal Failure with Cross-Contamination
Common · high severityTypical onset: 90,000-140,000 mi
Symptoms: milky or strawberry-colored transmission fluid, transmission slipping or delayed engagement, coolant level dropping without external leaks, overheating transmission
Fix: The internal cooler in the radiator develops pinhole leaks, allowing coolant into ATF and vice-versa. This destroys the transmission within days if not caught. Requires radiator replacement, complete transmission flush or rebuild, all cooler lines flushed—12-20 hours if trans needs rebuild. Preventive external cooler install recommended.
Estimated cost: $1,200-4,500
Alternator Voltage Regulator Failure
Occasional · medium severityTypical onset: 100,000-150,000 mi
Symptoms: battery light intermittent or steady on dash, voltage gauge reading low or fluctuating, electrical accessories dimming, no-start after short trips, new battery dies repeatedly
Fix: Mitsubishi-supplied alternators have weak internal regulators that fail, undercharging the system. NHTSA had two recalls related to alternator issues. Replacement alternator needed—2.5 hours labor. Test charging voltage before replacing battery.
Estimated cost: $450-700
Transmission Mounts Collapsing
Common · medium severityTypical onset: 70,000-120,000 mi
Symptoms: heavy clunk when shifting into drive or reverse, vibration at idle in gear, excessive driveline movement on acceleration, visible sag of transmission tailshaft
Fix: Rubber transmission mounts deteriorate and collapse, allowing the heavy transmission to drop and bang against crossmember. Inspect all engine and trans mounts together—replacements are 3-4 hours labor total. OEM mounts far outlast aftermarket.
Estimated cost: $400-650
Rear Subframe Bushing Deterioration
Occasional · low severityTypical onset: 80,000-130,000 mi
Symptoms: clunking over bumps from rear, vague or wandering rear-end feel, uneven rear tire wear, rear axle feeling loose or disconnected on rough roads
Fix: The rear subframe uses large rubber bushings that crack and tear with age. Handling degrades noticeably. Requires subframe drop to replace—6-8 hours labor. Polyurethane replacements available but transmit more NVH.
Estimated cost: $800-1,200
Fuel Filter Clogging and Fuel Pump Strain
Occasional · medium severitySymptoms: stumbling or hesitation under acceleration, rough idle after sitting, hard starting when hot, loss of power at highway speeds
Fix: In-tank fuel filter rarely gets changed (requires pump removal), leading to clogging and pump failure. Pump/filter assembly replacement is 3-4 hours. If vehicle history is unknown, replace proactively—V8 is sensitive to fuel pressure fluctuations.
Estimated cost: $500-800
Only buy if you have compression test results proving healthy bores and confirmed transmission fluid is clean—otherwise you're buying someone else's $8,000+ problem waiting to happen.
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.