Crankshaft pulley bolt loosens and the pulley departs

This is the defining mechanical failure of the second-generation Montero and the one worth knowing before anything else on the engine. Mitsubishi's United States recall states that the bolt securing the crankshaft pulley can work loose and that the pulley can then fall off the vehicle, and it names the consequence in plain terms: loss of power steering assist, with an increased risk of a crash. The pulley is what drives every belt on the front of the engine, so when it leaves, the steering pump, the alternator and the water pump all stop at once — heavy steering, no charging and a rising temperature gauge, arriving together and without warning. Owner reports filed with the same agency are unusually numerous for this component and they add two things the campaign does not: some describe the bolt loosening again after it was tightened, and several describe the crankshaft nose itself being chewed out, which turns a fastener job into an engine. **Read the campaign's scope carefully, because it is narrower than the truck.** It names Monteros fitted with the smaller of the two petrol V6s, and the fitment above is set to that engine for exactly that reason — a truck with the larger V6 was never part of it. That boundary is not a statement that the larger engine is immune, and the cited owner reports are blunt about how it felt from outside: one asks why there is no recall for the bigger engine, another records being told their truck was excluded by its identification number. Owners of an excluded truck get the same inspection and none of the free repair. Treat a knock or a visible wobble at the front of the engine as this fault until it is proven otherwise, whichever engine you have, and do not drive the truck to find out.

Gen 21992–1996USSafety-criticalTechnical service bulletin (TSB)

Do not driveNo lo maneje

Safety notice — Engine.

This affects a safety-critical system. Reference material only: for safety-critical work, consult a qualified mechanic.

Esto afecta un sistema crítico para la seguridad. Material de referencia únicamente: en trabajos críticos para la seguridad, consulte a un mecánico calificado.

Symptoms

A knock or rattle from the front of the engine that changes with engine speed
The bottom pulley visibly wobbles or moves in and out while the engine idles
The steering suddenly goes heavy while driving
The charge warning lamp lights and the temperature gauge climbs at the same moment
The drive belts are thrown off the engine

Likely causes

The crankshaft pulley bolt has loosened
The crankshaft nose or its keyway is already chewed out
The rubber ring inside the harmonic damper has separated
A seized accessory pulley or idler is dragging on the belt

Diagnostic steps

With the engine idling and the bonnet open, watch the bottom pulley from the side and from the front for in-and-out movement or a visible wobble — stand clear of the beltsPoints toThe crankshaft pulley bolt has loosened · The rubber ring inside the harmonic damper has separatedRules outA seized accessory pulley or idler is dragging on the belt
Aim a timing light at the mark on the pulley rim and watch whether it holds still or drifts around the scalePoints toThe rubber ring inside the harmonic damper has separatedRules outThe crankshaft pulley bolt has loosened
With the engine off, check the bolt against the factory torque figure and look at the washer face and the pulley for fretting or bright metalPoints toThe crankshaft pulley bolt has loosenedRules outThe rubber ring inside the harmonic damper has separated
Remove the pulley and inspect the crankshaft nose, the keyway and the key for rounding, steps or gallPoints toThe crankshaft nose or its keyway is already chewed outRules outThe crankshaft pulley bolt has loosened
With the belts off, turn the alternator, the steering pump, the water pump and each idler by hand and feel for roughness or dragPoints toA seized accessory pulley or idler is dragging on the beltRules outThe crankshaft nose or its keyway is already chewed out

Fix paths

Torque the pulley bolt to the factory figure, and replace it if it is damaged

$–$$Difficulty 4/5

This is the campaign's own remedy for this model where the pulley and the crankshaft nose are undamaged, and it is worth stating precisely because the campaign covers more than one vehicle and does not prescribe the same thing for all of them: on these trucks the bolt is tightened to the correct torque specification, and replaced only if it is found damaged. Two of the cited owner reports describe exactly that being done — one records the bolt inspected and never replaced, another simply that the mechanic tightened it. Use a torque wrench and clean, dry mating faces. Guessing at this fastener is how the failure repeats.

Replace the crankshaft pulley and damper

$$–$$$Difficulty 4/5

Once the rubber ring has separated, the outer rim runs out of time with the hub, the timing mark wanders and the belts see a pulley that is no longer round to them. A damper is replaced, never welded or bonded back together.

Repair or replace the crankshaft

$$$–$$$$Difficulty 5/5

If the nose or keyway is chewed out there is nothing left for the bolt to clamp against, and this stops being a bolt job. Owner reports describe getting to the point of needing the engine replaced. Have a machine shop or a qualified mechanic judge whether the nose can be saved before anything else is bought.

Sources

NHTSA safety recall 00V311001 (Mitsubishi) — crankshaft pulley bolt can loosen and the pulley can fall off, with loss of power steering assist; the Montero half of the campaign is scoped to trucks with the 3.0L engineManufacturer literaturearchived copy2026-09-02
NHTSA owner complaint database — 1995 Mitsubishi MonteroReference workarchived copy2026-09-02
NHTSA owner complaint database — 1997 Mitsubishi Montero — note the year's dataset also carries Montero Sport records, a different platform, which are excluded from what is relied on hereReference workarchived copy2026-09-02
NHTSA owner complaint database — 1999 Mitsubishi MonteroReference workarchived copy2026-09-02