The 2000 Montero (Gen 3) is a capable off-roader plagued by catastrophic engine failures on 3.5L models and chronic transmission overheating. When they run, they're solid, but budget heavily for preventive maintenance or risk a complete powertrain replacement.
3.5L V6 Crankshaft and Bearing Failure
Common · high severityTypical onset: 80,000-150,000 mi
Symptoms: Rod knock or deep knocking from bottom end, Metal shavings in oil, Low oil pressure warning, Catastrophic engine seizure if ignored
Fix: The 6G74 3.5L has undersized crankshaft journals that wear prematurely, wiping bearings and sometimes spinning rods. Full engine rebuild (crank grind, bearings, rings, gaskets) takes 18-24 hours labor. Many shops recommend short block replacement or used engine swap instead due to machine work costs. Preventive: oil changes every 3k miles religiously.
Estimated cost: $3,500-6,500
Automatic Transmission Overheating and Cooler Failure
Common · high severityTypical onset: 60,000-120,000 mi
Symptoms: Burnt transmission fluid smell, Harsh or delayed shifts when hot, Transmission slipping under load, Check engine light with trans temp codes
Fix: Factory transmission oil cooler is undersized and mounted in radiator end tank—prone to leaking coolant into ATF (strawberry milkshake effect) or simply not cooling enough. Replace with external aftermarket cooler (3-4 hours), flush trans completely. If contamination occurred, rebuild or replacement needed (15-20 hours). Catch early or face $4k+ rebuild.
Estimated cost: $400-800 (cooler upgrade); $2,800-4,500 (rebuild)
Head Gasket Failure (Both Heads)
Occasional · high severityTypical onset: 100,000-160,000 mi
Symptoms: White smoke from exhaust, Overheating with no external leaks, Coolant consumption without visible puddles, Rough idle or misfire, Oil contamination in coolant reservoir
Fix: Both 3.0L and 3.5L can blow head gaskets, especially if overheated. Job requires removing intake manifold, exhaust, both heads (12-16 hours labor). Always resurface heads, replace timing belt/water pump while in there. The 3.5L's bearing issues often cause overheating that accelerates gasket failure—check crank journals if doing heads.
Estimated cost: $2,200-3,800
Transfer Case Mode Sensor and Actuator Failure
Occasional · medium severityTypical onset: 70,000-130,000 mi
Symptoms: 4WD indicator lights flashing or incorrect, Unable to engage or disengage 4WD, Grinding when trying to shift transfer case, Check engine light with 4WD system codes
Fix: Electronic shift-on-the-fly system uses sensors and actuators that corrode or fail. Diagnosis takes 1-2 hours; actuator replacement is 2-3 hours, sensor replacement 1-2 hours. Sometimes just cleaning connectors works. Worst case is internal transfer case issues (rare but expensive). Most common fix is actuator motor replacement.
Estimated cost: $400-900
Front Differential and CV Axle Wear
Common · medium severityTypical onset: 90,000-140,000 mi
Symptoms: Clunking from front end during turns, Grease on inside of wheel, Clicking or popping when turning, Vibration during acceleration
Fix: Front CV axles wear boots and joints, especially with off-road use. Axle replacement is 2-3 hours per side. Front diff can also develop bearing noise or leak—service involves draining, resealing, bearing replacement if needed (4-6 hours). CV boots can be replaced alone if caught early (1.5 hours per side), but most opt for loaded axle replacement.
Estimated cost: $300-500 per axle; $800-1,400 (diff work)
Rear Main Seal and Oil Pan Gasket Leaks
Occasional · low severityTypical onset: 100,000+ mi
Symptoms: Oil spots under vehicle after parking, Oil coating on back of engine/bellhousing, Burning oil smell from exhaust heat, Low oil level between changes
Fix: Age and heat cause rear main seal and oil pan gasket to weep. Rear main requires transmission removal (8-10 hours labor), oil pan is easier (3-4 hours but requires subframe drop). Often done together if trans is already out for other work. Not urgent if leak is slow, but keep oil topped up.
Estimated cost: $600-900 (pan); $1,200-1,800 (rear main)
Alternator and Voltage Regulator Failure
Occasional · medium severityTypical onset: 80,000-130,000 mi
Symptoms: Battery light on dash, Dimming lights at idle, Electrical accessories acting erratically, Battery repeatedly dying, Voltage gauge reading low or high
Fix: Mitsubishi alternators of this era have weak voltage regulators that fail, causing undercharging or overcharging. Replacement is straightforward (1.5-2 hours), but verify battery and charging system first. Use quality remanufactured units—cheap ones fail quickly. Some models have tight access requiring removal of other components.
Estimated cost: $350-600
Buy only if you find a meticulously maintained 3.0L or are prepared to grenade-proof a 3.5L with immediate cooler upgrade and religious oil analysis—otherwise, budget $5k+ for eventual engine work.
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.