1991 MITSUBISHI 3000GT

Typical onset: 80,000-120,000 mi

Symptoms: blue smoke on acceleration, loss of boost pressure, whining or grinding noise from turbo, oil consumption over 1qt per 1000mi, check engine light with boost codes

Fix: Turbos fail from oil coking in the CHRA due to inadequate cooldown procedures and age-hardened oil lines. Requires turbo removal (8-10 hours labor due to firewall-side access), replacement of both turbos, all oil feed and drain lines, and often the exhaust manifold studs which snap. Smart shops do head gaskets at same time since you're already there.

Estimated cost: $3,500-6,500

Typical onset: 100,000-150,000 mi

Symptoms: heavy knocking on cold start that quiets when warm, metallic rattling under load, oil pressure drop at idle, metal shavings in oil filter, sudden catastrophic failure with loss of oil pressure

Fix: The 6G72TT is notorious for bearing failure, especially if oil changes were delayed or wrong oil used. Minimum fix is rod bearings, but most need mains, thrust washers, and often a crank polish or replacement. Full rebuild with pistons, rings, and head gaskets runs 30-40 hours labor. Engine-out is nearly mandatory given the firewall clearance. Short block swap is 25-30 hours.

Estimated cost: $5,000-9,000

Typical onset: 90,000-130,000 mi

Symptoms: overheating with no visible leaks, white smoke from exhaust, milky oil or coolant loss without external puddles, rough idle and misfires, bubbling in coolant reservoir

Fix: The MLS gaskets fail between cylinders or into the coolant jackets. Both heads must come off (12-16 hours labor) due to transverse V6 layout. Requires head resurfacing, new timing belt/water pump while you're in there, and all associated seals. Rear bank is a nightmare — steering rack and crossmember often need to drop for clearance.

Estimated cost: $2,800-4,500

Typical onset: 100,000-140,000 mi

Symptoms: grinding or clunking during turns, binding feeling in tight parking maneuvers, AWD warning light, vibration at highway speeds, fluid leaking from transfer case

Fix: The active center diff and transfer case share fluid and wear synchro-style clutch packs. Neglected fluid changes cause bearing and gear wear. Requires transmission drop (8-10 hours) and transfer case rebuild or replacement. Used units are scarce and often damaged. Mitsubishi part was $3,200+ when available; now mostly aftermarket or junkyard hunting.

Estimated cost: $2,000-4,000

Typical onset: varies, age-related

Symptoms: rear spoiler stuck up or down, front airdam motors buzzing but not moving, warning light on dash, slow or jerky movement of aero components

Fix: Motor gearboxes strip plastic gears, hydraulic lines crack, and speed sensors fail. Spoiler can be manually locked in position (1 hour). Full repair requires motor replacement (2-3 hours per corner), bleeding hydraulic system, and sometimes speed sensor recalibration. Parts are NLA from Mitsubishi; used or aftermarket only.

Estimated cost: $800-1,800

Typical onset: varies, age-related

Symptoms: soft or spongy brake pedal that doesn't firm up with bleeding, pedal slowly sinks to floor under steady pressure, visible brake fluid leak at master cylinder or along frame rails, corrosion visible on steel brake lines near rear subframe

Fix: Master cylinder internal seals fail (2 hours to replace, requires bench bleeding). More serious: steel brake lines rust through at bends and brackets, especially rear section — this is a factory recall area but many weren't caught. Full hard line replacement from master to all four corners runs 6-8 hours and requires lift access. Don't skip this — brake failure is sudden.

Estimated cost: $600-1,800

Typical onset: 80,000+ mi

Symptoms: transmission fluid leak at radiator or under engine, harsh or delayed shifts, transmission overheating, fluid puddles after parking, low fluid level on dipstick

Fix: Cooler lines crack at crimp fittings and rubber sections harden with age. Transmission mounts (especially rear) collapse, causing driveline vibration and misalignment that accelerates wear. Cooler line replacement is 2-3 hours; all three mounts together are 4-5 hours due to subframe access. Do them together to avoid comeback.

Estimated cost: $600-1,200