1997 Mitsubishi Montero Problems: 5 Known Issues

On the 1990-1999 Mitsubishi Montero, both the 3.0L 6G72 and the 3.5L 6G74 V6s used in the 1990s Montero are driven by a rubber timing belt, and on the interference versions, if the belt snaps or is contaminated by oil leaking from the front cover/cam seals, the pistons strike the open valves and bend them. Sources disagree on whether the early 3.0L trucks through 1993 are interference engines; the 1994-and-later 3.0L and the 3.5L 6G74 are interference. Treat every Montero V6 as interference to be safe. Many 1990s Monteros are now well past any documented belt service, making this the single most consequential neglected item on the platform.

On the 1990-1999 Mitsubishi Montero, as the 6G72 and 6G74 V6s age, the valve stem seals harden and crack and the piston rings/valve guides wear, allowing oil into the combustion chamber. This is one of the most widely reported 90s Montero engine complaints. Owners report consumption on the order of a quart every 1,000-1,500 miles with bluish smoke that is worst on cold startup (after the engine sits, oil seeps past the seals and burns off in a plume) and on deceleration. Note that the underlying cause is often worn valve guides, so seal replacement can be a band-aid; Mitsubishi's general warranty policy treats about 1 quart per 1,000 miles as acceptable oil consumption.

On the 1990-1999 Mitsubishi Montero, the 6G72's crank/cam timing signal on early 1990s trucks is generated inside the distributor, and later trucks use a discrete crankshaft position sensor at the front of the engine behind the crank pulley/timing covers. As these sensors and their pickups age they fail intermittently, producing a classic 'cranks but won't start' condition or sudden stalling while driving that often clears after the engine cools. Owners repeatedly report that aftermarket sensors do not resolve the problem and that only a genuine Mitsubishi (OEM) sensor restores reliable operation; the crank sprocket tone/reluctor ring can also strip or be damaged.

On the 1994-1999 Mitsubishi Montero, the Aisin-based 4-speed automatic (V4AW2/V4AW3) behind the Montero V6 develops a torque-converter lockup (damper-clutch) shudder as it ages, felt as a vibration or 'buzz' typically in the 35-50 mph range at steady throttle that owners often mistake for an engine misfire. A later Mitsubishi TSB attributes the same symptom to breakdown of the ATF causing damper-clutch shudder; that bulletin was issued for the 2001-2003 Montero and 1999-2003 Montero Sport (on 1999 Montero Sport RWD models it can also cause rear leaf-spring chatter), not for the 1990s Montero covered here. Neglected or overheated fluid, common on trucks that tow or wheel, also leads to worn clutch packs, slipping, delayed engagement, and harsh or missed shifts.

On the 1992-1999 Mitsubishi Montero, the Montero's Super Select 4WD (second-generation, 1992+) engages the front axle through a vacuum-operated free-wheel actuator and electric solenoids rather than a mechanical linkage from the shifter. Over decades the dual-solenoid pack fails, the rubber hoses deteriorate, and the front differential actuator (a small shaft under a rubber boot on the passenger side of the front diff) can rust or seize, especially after long storage. The result is a truck that will not engage or disengage 4WD properly, gets stuck in 2WD or 4WD, grinds from the front axle, or flashes the 4WD indicator lights. This is a signature, well-documented failure mode discussed extensively in the overland/Expedition Portal community.