2002 PONTIAC MONTANA

Typical onset: 60,000-100,000 mi

Symptoms: External coolant leaks at front/rear of engine, White smoke from exhaust on cold start, Coolant mixing with oil (milky dipstick), Overheating, Rough idle and misfires

Fix: Complete intake manifold gasket replacement requires removing upper plenum, fuel rails, and various sensors. The Dex-Cool coolant becomes acidic and eats the composite gaskets. Plan 6-8 hours labor, always replace upper gaskets too while you're in there. Flush entire cooling system and switch to conventional green coolant.

Estimated cost: $800-1,400

Typical onset: 80,000-150,000 mi

Symptoms: Pink milkshake in coolant reservoir (transmission fluid in coolant), Transmission slipping or no forward gears, Rapid transmission fluid loss, Check engine light with transmission codes

Fix: Steel cooler lines rust through where they connect to the radiator, allowing coolant to mix with ATF and destroying clutch packs. Once contaminated, the 4T65-E is usually toast. Requires transmission rebuild or replacement (10-14 hours), new radiator, complete fluid flush of both systems. This is THE killer for these vans—check lines religiously.

Estimated cost: $2,500-4,500

Typical onset: 100,000-150,000 mi

Symptoms: External coolant leaks from cylinder heads, White exhaust smoke, Overheating with no visible leaks, Combustion gases in cooling system, Loss of coolant with no puddles

Fix: The 3.4L is prone to head gasket failure, often following overheating from intake gasket issues. Requires cylinder head removal on both banks (12-16 hours), resurfacing heads, new head bolts. Often discover warped heads adding $400-600 for machine work. If caught early before overheating damage, can prevent full engine rebuild.

Estimated cost: $1,800-2,800

Typical onset: 70,000-120,000 mi

Symptoms: Severe clunk when shifting from Park to Drive/Reverse, Vibration at idle in gear, Visible engine/transmission movement when accelerating, Difficulty shifting smoothly

Fix: The rear transmission mount deteriorates and the hydraulic front mount fails, allowing excessive drivetrain movement. Fairly straightforward replacement (2-3 hours) but requires supporting the engine/trans. Replace both front and rear mounts together—doing one at a time means you're back under there in 6 months.

Estimated cost: $300-500

Typical onset: any mileage

Symptoms: Door won't latch electrically, must slam manually, Door opens while driving (recall-related), Motor runs but door doesn't move, Grinding noise from door mechanism

Fix: The power sliding door actuators and latches wear out or break internal gears. GM issued recalls for some latch failures. Actuator replacement takes 2-3 hours per side including door panel removal and cable adjustment. Many owners simply disable the power function and use manual mode.

Estimated cost: $400-700

Typical onset: 100,000-150,000 mi

Symptoms: No-start condition with crank but no fire, Stalling when fuel tank below 1/4 full, Loss of power under acceleration, Whining noise from rear of vehicle

Fix: The in-tank fuel pump assembly fails, often the pump motor itself. Requires dropping the fuel tank (2.5-3.5 hours). Access is cramped with the rear suspension and exhaust in the way. Always replace the entire pump module with strainer, not just the pump motor, to avoid comeback.

Estimated cost: $500-800