1994 PONTIAC BONNEVILLE

Typical onset: 80,000-140,000 mi

Symptoms: Heavy oil consumption (quart every 500-800 miles), Blue smoke on startup or acceleration, Rod knock or deep rattling from crankcase at idle, Loss of boost pressure, lack of power, Metal shavings in oil during changes

Fix: Early supercharged Series II engines used weak hypereutectic pistons that crack ring lands under boost. Rings lose tension, oil consumption skyrockets, bearings get oil-starved. Requires full short-block replacement or engine rebuild with forged pistons. 18-24 labor hours for R&R and rebuild, plus machine work.

Estimated cost: $3,500-6,000

Typical onset: 90,000-150,000 mi

Symptoms: Pink milkshake in coolant reservoir (trans fluid mixing with coolant), Transmission slipping or delayed engagement after engine reaches temp, Coolant level dropping with no external leaks, White smoke from exhaust if coolant enters trans badly

Fix: Plastic radiator end tanks crack where cooler lines attach, or internal trans cooler fails, cross-contaminating fluids. Requires radiator replacement, complete trans fluid flush (often multiple exchanges), filter change. If contamination sat for days, trans rebuild likely. 4-6 hours for radiator and flush; add 12-18 for trans rebuild if damaged.

Estimated cost: $800-1,200 (catch early), $2,500-3,800 (if trans damaged)

Typical onset: 70,000-120,000 mi

Symptoms: Severe clunk when shifting from park to drive or reverse, Vibration at idle that changes when shifting to gear, Visible engine/trans sag on passenger side, Axle angle issues causing CV boot tears

Fix: The hydraulic transmission mount fails internally, allowing excessive powertrain movement. Supercharged torque accelerates wear. Simple replacement but requires supporting powertrain. 1.5-2.5 hours labor.

Estimated cost: $250-450

Typical onset: 100,000-160,000 mi

Symptoms: High-pitched squealing or grinding from supercharger area, Loss of boost pressure, Black rubber dust around supercharger snout, Supercharger oil leaking from front seal

Fix: The rubber coupler connecting supercharger to snout wears out, or the snout bearing itself fails. Supercharger must be removed for coupler replacement; bearing requires complete rebuild or replacement. 6-9 hours for supercharger R&R and rebuild.

Estimated cost: $800-1,500

Typical onset: 110,000-180,000 mi

Symptoms: White smoke from exhaust, Coolant loss with no external leaks, Overheating under load, Oil contamination in coolant (tan residue under cap), Misfires and rough idle

Fix: Boosted engines stress gaskets; Dex-Cool can accelerate gasket degradation if not maintained. Both heads typically need work if one fails. Requires head removal, resurfacing, new gaskets. 12-16 hours labor.

Estimated cost: $2,200-3,500

Typical onset: 80,000-140,000 mi

Symptoms: Hard starting when engine is hot, Stalling or hesitation under boost, Loss of power at highway speeds, Whining noise from fuel tank area

Fix: The supercharged engine is sensitive to fuel pressure drops. In-tank pump wears, or filter clogs (especially if old gas sat). Filter is inline under car; pump requires tank drop. 2-3 hours for filter, 3-4 for pump replacement.

Estimated cost: $300-500 (filter and pump together)