1994 MITSUBISHI DIAMANTE

Typical onset: 80,000-140,000 mi

Symptoms: Knocking or ticking from lower engine, Oil pressure warning light flickering or staying on, Metal shavings in oil, Sudden loss of power and seizing

Fix: The 6G72 is notorious for oil sludge accumulation in the valve train and oil passages, starving bearings and destroying the crank. Poor PCV maintenance and extended oil changes accelerate this. Repair requires full engine rebuild (connecting rod bearings, main bearings, crankshaft grinding or replacement, new pistons/rings) or short block replacement. Budget 20-30 labor hours for rebuild, 12-16 for short block swap.

Estimated cost: $3,500-6,500

Typical onset: 90,000-130,000 mi

Symptoms: Pink or milky transmission fluid, Transmission slipping or refusing to shift, Coolant loss with no visible leaks, Transmission overheating

Fix: The internal transmission cooler (inside the radiator) corrodes and fails, allowing coolant and ATF to mix. This ruins the transmission and contaminates the cooling system. Requires radiator replacement, transmission flush or rebuild if contamination occurred, and all cooler lines replaced. If caught early (external line rupture only), 3-4 hours. If cross-contamination happened, add transmission rebuild at 12-18 hours.

Estimated cost: $800-1,200 (lines/radiator only), $2,800-4,500 (with transmission rebuild)

Typical onset: 100,000-150,000 mi

Symptoms: White smoke from exhaust, Coolant disappearing with no external leaks, Overheating under load, Oil contaminated with coolant (chocolate milk appearance)

Fix: The V6 head gaskets fail, often on both banks simultaneously due to overheating or age. Requires removing intake manifold, exhaust manifolds, timing belt, and both heads. Always replace timing belt, water pump, and thermostat during this job. Plan for 16-20 hours labor, more if heads need machining.

Estimated cost: $2,200-3,800

Typical onset: 70,000-110,000 mi

Symptoms: Clunking when shifting from Park to Drive/Reverse, Excessive vibration at idle, Visible engine/trans movement when revving in Park

Fix: The hydraulic transmission mount fails and collapses, allowing the powertrain to shift excessively. Replacement is straightforward but requires supporting the transmission. 2-3 hours labor.

Estimated cost: $350-550

Symptoms: Brake pedal goes to floor, Fluid leaking near wheels or along frame rails, Brake warning light on, Loss of braking on one or more wheels

Fix: Steel brake lines rust through, particularly in salt-belt states. NHTSA recalls addressed some lines but not all. Requires replacing corroded sections or full brake line kit. 4-8 hours depending on how many lines are affected and whether you're doing pre-bent replacements or custom flaring.

Estimated cost: $600-1,400

Typical onset: 80,000-120,000 mi

Symptoms: Hard starting, especially when hot, Stumbling or hesitation under acceleration, Stalling at idle after driving, Check engine light with lean codes

Fix: The inline fuel filter clogs if not replaced regularly (Mitsubishi spec: every 60k mi, but often ignored). A clogged filter overworks the in-tank pump, leading to premature pump failure. Filter replacement is 1 hour; if the pump is damaged, add 3-4 hours for tank drop and pump replacement.

Estimated cost: $120-200 (filter only), $650-950 (filter + pump)