2012 GMC YUKON XL 2500

Typical onset: 100,000-180,000 mi

Symptoms: Blue smoke on startup or acceleration, Burning through 1+ quart of oil every 500-1,000 miles, Fouled spark plugs, Loss of power under load, Check engine light with misfire codes

Fix: Requires complete engine teardown to replace piston rings on all cylinders, often combined with cylinder honing and ridge reaming. Realistically 20-30 hours labor depending on damage severity. Many owners opt for short block replacement or full rebuild if bearings show wear. If caught early, just rings and honing; if delayed, expect crankshaft polishing or replacement.

Estimated cost: $4,500-8,500

Typical onset: 80,000-150,000 mi

Symptoms: Ticking or tapping noise from valve train, especially cold starts, Check engine light with P0300-series misfire codes or lifter collapse codes, Rough idle, Metal shavings in oil, Sudden loss of compression in affected cylinders

Fix: AFM system uses collapsible lifters that fail and can wipe cam lobes. Requires cam replacement, all lifters, often pushrods, and valley cover gaskets. Minimum 16-20 hours labor. Smart owners delete AFM during repair with aftermarket non-AFM cam and lifters. If debris circulated, oil pump and bearings may need inspection.

Estimated cost: $3,500-6,000

Typical onset: 60,000-120,000 mi

Symptoms: Transmission fluid in coolant (strawberry milkshake appearance in overflow), Coolant in transmission (burnt smell, slipping, erratic shifting), Transmission overheating, Check engine light or reduced power mode, External leaks at radiator cooler connections

Fix: The internal transmission cooler in the radiator corrodes and allows fluid mixing. Requires new radiator, complete cooling system flush, transmission flush or replacement if contaminated badly, and often new torque converter. Trans rebuild needed if coolant reached clutches. 8-12 hours labor for radiator and flushes; add 18-25 hours if transmission needs rebuild.

Estimated cost: $1,200-6,500

Typical onset: 150,000-250,000 mi

Symptoms: Deep knocking noise from bottom end, worse under load, Low oil pressure warnings at idle when warm, Metallic debris on oil drain plug magnet, Gradual loss of power, Oil pressure gauge fluctuations

Fix: High-mileage bearing wear, often accelerated by oil consumption issues going unnoticed. Requires crankshaft removal, inspection, and polishing or replacement. Rod and main bearings replaced, often with upgraded aftermarket units. If crank is damaged beyond spec, core engine replacement becomes more economical. 25-35 hours for full bottom-end rebuild.

Estimated cost: $5,000-9,000

Typical onset: 80,000-140,000 mi

Symptoms: Clunking when shifting from Park to Drive or Reverse, Excessive vibration at idle in gear, Visible sagging of transmission tailshaft, Harsh engagement into gear

Fix: The rubber transmission mount deteriorates and allows excessive drivetrain movement. Straightforward replacement requiring transmission support and mount removal. 1.5-2.5 hours labor. Often replaced alongside motor mounts as preventive measure.

Estimated cost: $250-450

Typical onset: 120,000-200,000 mi

Symptoms: White smoke from exhaust, Coolant loss with no external leaks, Overheating under load, Oil milky on dipstick, Bubbles in coolant overflow tank, Misfires on one bank

Fix: The 6.0L can blow head gaskets from overheating or age. Both heads should be removed, inspected, and resurfaced. New gaskets, head bolts, intake gaskets, and coolant. Realistically 14-18 hours labor. If heads are warped beyond machining limits, add $800-1,200 per head for replacement or rebuilds.

Estimated cost: $3,000-5,500

Symptoms: Hard starting after sitting, Loss of power under acceleration or towing, Sputtering at highway speeds, Check engine light with fuel trim or pressure codes, Fuel pump whining noise

Fix: The in-tank fuel filter and pump assembly can clog from contaminated fuel or age, causing pump to work harder and fail prematurely. Requires tank drop and pump/filter module replacement. 3-4 hours labor. Often overlooked maintenance item; GM recommends replacement at 100k but many go longer.

Estimated cost: $600-1,100