2007 PONTIAC MONTANA

Typical onset: 90,000-140,000 mi

Symptoms: Harsh 1-2 or 2-3 shifts, slipping under load, Pink or milky transmission fluid (cooler leak mixing with coolant), Delayed engagement when shifting to Drive or Reverse, Metal shavings on dipstick or in pan

Fix: The transmission oil cooler inside the radiator is a known weak point—it leaks coolant into the trans, destroying clutches and causing catastrophic failure. Repair requires transmission rebuild or replacement (8-12 hours labor) plus radiator with integrated cooler. Many shops install an external trans cooler as preventive measure. If you catch the cooler leak early (pink fluid), flushing and replacing radiator can save the trans.

Estimated cost: $2,800-4,500

Typical onset: 80,000-120,000 mi

Symptoms: Coolant loss with no visible external leaks, White smoke from exhaust on cold start, Rough idle or misfire codes (coolant in cylinders), Milky oil if severe (head gasket territory)

Fix: GM's Dex-Cool coolant and plastic gasket design leads to deterioration. Lower intake manifold gaskets leak coolant internally. Job requires removing upper plenum, fuel rails, and various sensors. Plan 5-7 hours labor. Always replace upper gaskets, PCV valve, and thermostat during this job. Use updated aftermarket gaskets (Felpro MS98000T or equivalent).

Estimated cost: $800-1,400

Typical onset: 70,000-110,000 mi

Symptoms: Whining or groaning when turning, especially when cold, Fluid drips under front of vehicle (usually passenger side), Heavy steering effort or jerky assist, Low fluid level requiring frequent top-offs

Fix: High-pressure lines and pump seals fail from heat cycling. Often see fitting corrosion where aluminum lines meet steel. Pump replacement is 2-3 hours; if lines are leaking at fittings, budget another hour. Flush system and use proper GM power steering fluid—ATF substitutes accelerate seal failure on these pumps.

Estimated cost: $450-750

Typical onset: 100,000+ mi

Symptoms: Rear end sits low, especially when loaded, Clunking over bumps from rear, Uneven tire wear on rear tires, Bottoming out with passengers or cargo

Fix: Rear coil springs fatigue and the upper spring seats crack. NHTSA had a recall for rear suspension on some units. Replacing both rear springs and isolators is 3-4 hours. While you're in there, inspect rear shocks—they're usually shot by this point too. Sometimes the issue is just worn rubber isolators, but springs are cheap insurance.

Estimated cost: $500-900

Typical onset: 120,000+ mi

Symptoms: Low oil level between changes (1 quart per 1,000-2,000 miles), Blue smoke on deceleration or startup, Carbon buildup on spark plugs, No external leaks visible

Fix: Valve stem seals harden with age, and piston rings can wear in the bore. If caught early, some techs try valve seal replacement (heads off, 8-10 hours) for $1,200-1,800. High consumption often means bore wear requiring re-ring or short block (16-20+ hours). Not economical on a vehicle this old—most owners just monitor oil and add as needed until disposal.

Estimated cost: $1,200-4,000

Typical onset: 110,000-150,000 mi

Symptoms: No-start with crank, no fuel pressure, Intermittent stalling, especially in hot weather, Whining noise from rear of vehicle, Loss of power under load or acceleration

Fix: In-tank pump fails from wear or contamination. Requires dropping the fuel tank (or removing rear seat and cutting access panel if not already present). Plan 2-3 hours labor. Use OE-quality pump assembly (AC Delco or equivalent)—cheap aftermarket pumps fail within a year. Replace fuel filter at same time if it hasn't been done recently.

Estimated cost: $600-950