2010 PONTIAC G6

Typical onset: 80,000-120,000 mi

Symptoms: Rattling noise on cold start that goes away after warmup, Check engine light with cam/crank correlation codes (P0016, P0017), Sudden catastrophic failure: pistons hit valves, metal debris through entire engine, Oil consumption between changes (early warning sign)

Fix: Timing chain stretches, guides break, engine jumps time and self-destructs. By the time you hear it, damage is often done. Used engine swap is most economical: 12-16 hours labor. Rebuild with updated tensioner/guides runs 25-35 hours but hard to justify on this platform. See this weekly in the shop.

Estimated cost: $3,500-6,500

Typical onset: 70,000-110,000 mi

Symptoms: Pink fluid puddle under vehicle (trans fluid mixed with coolant), Transmission slipping or delayed engagement after cooler fails, Milky/strawberry-colored transmission fluid on dipstick, Overheating transmission, burnt smell

Fix: Steel cooler lines rust through where they connect to radiator, especially in salt states. Trans fluid mixes with coolant, destroying both systems. Requires cooler line replacement (2-3 hours), often radiator too (add 3 hours), full trans fluid flush, sometimes transmission replacement if contaminated coolant got circulated. Seen dozens of these.

Estimated cost: $800-4,000

Typical onset: 90,000-140,000 mi

Symptoms: Harsh 2-3 or 3-4 shifts, especially when cold, Shuddering or slipping during acceleration, Check engine light with transmission codes (P0700 series), Delayed engagement into drive or reverse

Fix: The 6T70 six-speed has well-documented issues with 3-5-R clutch pack and wave plate failures. Aftermarket rebuild kits exist with updated parts. R&R and rebuild: 14-18 hours. Used transmission swap: 10-12 hours but gamble on same problems. Independent shops can rebuild cheaper than dealer.

Estimated cost: $2,800-4,200

Typical onset: 60,000-100,000 mi

Symptoms: Coolant smell in cabin or under hood, Coolant loss with no visible external leaks, Rough idle or misfire when cold, White smoke from exhaust on startup

Fix: Plastic intake manifold gaskets deteriorate, leak coolant into cylinders or externally. Upper and lower manifold removal required: 4-6 hours. Must replace both upper and lower gaskets, inspect runners for warpage. V6 models only, but we see it on every high-mile example.

Estimated cost: $650-1,100

Typical onset: 75,000-120,000 mi

Symptoms: Whining or groaning noise when turning wheel, Heavy steering effort, especially when cold, Power steering fluid leaking from hose near pump, Burning smell from fluid on exhaust

Fix: High-pressure hose develops leaks at crimps, pump wears out prematurely. Hose replacement: 1.5-2 hours. Pump replacement: 2-3 hours. Both often needed together if fluid ran low and damaged pump. Flush system after repairs to prevent repeat failure.

Estimated cost: $400-900

Symptoms: Check engine light with P0446, P0496, P0455 codes, Fuel smell around vehicle, Difficulty fueling (pump clicks off repeatedly), Rough idle when first starting after refueling

Fix: Purge solenoid and vent valve stick open or closed, causing emissions system codes. Purge valve is easy: 0.5 hours on engine. Vent valve requires fuel tank access: 2-3 hours. Diagnosis time adds cost if shop chases smoke. Common enough we stock the parts.

Estimated cost: $200-600