1998 MITSUBISHI MONTERO SPORT

Typical onset: 80,000-150,000 mi

Symptoms: Excessive oil consumption (1 quart per 500-1000 miles), Blue smoke on startup or acceleration, Knocking or rattling from bottom end, Loss of oil pressure, Metal shavings in oil

Fix: The 3.0L 6G72 engine is notorious for piston ring land failure and subsequent bearing damage from oil starvation. Requires complete engine rebuild (40-50 hours) or used engine swap (15-20 hours). Rebuilds often reveal scored cylinder walls requiring oversize pistons or sleeving. Many owners opt for junkyard engines due to rebuild costs exceeding vehicle value.

Estimated cost: $3,500-6,500

Typical onset: 90,000-140,000 mi

Symptoms: Pink or milky transmission fluid, Coolant in transmission pan, Transmission slipping or delayed engagement, Overheating transmission, Check engine light with transmission codes

Fix: The internal transmission cooler in the radiator fails, allowing coolant and ATF to mix—this destroys the transmission within days if not caught immediately. Requires radiator replacement, complete transmission fluid system flush (including cooler lines and torque converter), often transmission rebuild if contamination occurred. External cooler installation mandatory to prevent repeat failure. 8-12 hours for radiator/flush, add 18-25 hours if transmission damaged.

Estimated cost: $800-1,200 (caught early), $2,800-4,200 (transmission damaged)

Typical onset: 100,000-180,000 mi

Symptoms: White smoke from exhaust, Coolant loss with no visible leaks, Overheating, Rough idle or misfires, Coolant in oil (milky dipstick), External coolant seepage between head and block

Fix: The 6G72 V6 develops head gasket leaks, often related to overheating or age-related gasket degradation. Requires both head gaskets, resurfacing both heads, timing belt replacement while apart, and all associated seals. If overheated previously, heads may be warped beyond resurfacing limits. 22-28 hours labor. Often done alongside timing belt at high mileage.

Estimated cost: $2,200-3,800

Typical onset: 100,000-160,000 mi

Symptoms: Fluid leak from transfer case seals, Whining or grinding from center of vehicle, Difficulty engaging 4WD, Clunking when shifting into 4WD

Fix: Front output shaft seal and rear output seal commonly leak. If driven low on fluid, rear bearing fails causing expensive internal damage. Seal replacement is 3-4 hours. If bearing damaged, transfer case rebuild or replacement needed (8-12 hours). Check fluid level every oil change—these run dry without warning.

Estimated cost: $350-650 (seals only), $1,200-2,000 (bearing damage)

Typical onset: 80,000-130,000 mi

Symptoms: Clunking when shifting from Park to Drive/Reverse, Excessive vibration at idle in gear, Visible engine/transmission sag, Harsh engagement into gear

Fix: Rear transmission mount deteriorates, allowing excessive drivetrain movement. Rubber separates from metal bracket. Simple replacement, 1.5-2 hours. Inspect all engine/trans mounts simultaneously—they often fail together on high-mileage units.

Estimated cost: $180-320

Typical onset: 90,000-150,000 mi

Symptoms: Hard starting when hot, Hesitation or stumbling under acceleration, Loss of power uphill or under load, Stalling at idle or low speed

Fix: In-tank fuel pump weakens with age, and the inline fuel filter (often neglected) restricts flow. Filter replacement is 0.8-1 hour. Pump replacement requires dropping tank, 3-4 hours. Many mechanics replace both simultaneously at high mileage. Filter should be changed every 30,000 miles but rarely is.

Estimated cost: $120-220 (filter), $450-750 (pump)

Typical onset: 100,000+ mi

Symptoms: Gear oil dripping from front of rear differential, Oil coating driveshaft or rear of transmission, Whining from rear end if driven low on fluid

Fix: Pinion seal hardens and leaks. Requires driveshaft removal, seal replacement, sometimes pinion bearing preload adjustment. 2-3 hours. If driven low on fluid, ring and pinion damage occurs requiring full differential rebuild (8-10 hours). Check regularly—these leak slowly then suddenly worsen.

Estimated cost: $280-480