2002 OLDSMOBILE BRAVADA

Typical onset: 80,000-150,000 mi

Symptoms: Blue smoke on startup or acceleration, Burning through a quart of oil every 500-1,000 miles, Check engine light for misfire codes, Sudden rod knock or seized engine if oil level drops unnoticed

Fix: The LL8 I6 has weak piston ring design and valve seal issues that lead to excessive oil burning. Once advanced, requires full engine rebuild or replacement. Rebuild involves complete disassembly, new pistons, rings, bearings, seals — 18-24 labor hours. Many shops won't rebuild these anymore; used/reman engines are common.

Estimated cost: $4,500-7,500

Typical onset: 100,000-160,000 mi

Symptoms: Harsh 1-2 or 2-3 shifts, slipping under load, Transmission fluid puddling under vehicle from cooler lines, Delayed engagement into Drive or Reverse, Burnt fluid smell, dark brown or black ATF

Fix: The 4L60E in these trucks is marginal for the vehicle weight. Cooler lines rust through at the radiator connections (2-3 hours to replace lines). Full transmission rebuild or replacement is 8-12 hours. Always replace cooler lines during any transmission work to prevent contamination.

Estimated cost: $2,200-3,800

Typical onset: 60,000-100,000 mi

Symptoms: Coolant leak at front of engine, visible orange residue, Overheating or low coolant warnings, Rough idle, possible misfires if coolant enters cylinders, White smoke from exhaust if internal leak is severe

Fix: The LL8's plastic intake manifold gaskets deteriorate and leak coolant externally or internally. Requires removing intake plenum, replacing gaskets and often the manifold itself if warped. 5-7 hours labor. Can cause engine damage if coolant mixes with oil.

Estimated cost: $800-1,400

Typical onset: 70,000-120,000 mi

Symptoms: Service 4WD light illuminated on dash, Unable to shift into or out of 4WD modes, Grinding or clicking noise from transfer case area, 4WD engages randomly or won't disengage

Fix: The BorgWarner 4485 transfer case uses an electric encoder motor that fails, leaving you stuck in 2WD or 4WD. Motor replacement is 2-3 hours. If internal mode fork is damaged, transfer case teardown adds 6-8 hours. Diagnosis requires Tech 2 scanner.

Estimated cost: $450-1,200

Typical onset: 90,000-140,000 mi

Symptoms: Gear oil leak at pinion seal or axle tubes, Whining or growling noise from front axle during acceleration, Clunking when engaging 4WD or turning sharply, Vibration at highway speeds if bearings are worn

Fix: Front diff sees abuse from AWD operation. Pinion seal replacement is 3-4 hours. If carrier bearings or ring-and-pinion are worn, full rebuild is 8-10 hours and requires setup tools. Neglected leaks lead to catastrophic failure.

Estimated cost: $600-2,500

Typical onset: 80,000-130,000 mi

Symptoms: No-start condition, cranks but won't fire, Intermittent stalling, especially when fuel level is low, Fuel gauge reads erratically or stays on empty, Whining noise from fuel tank area

Fix: Fuel pump module in the tank fails, often taking out the level sender with it. Tank must be dropped for access — 3-4 hours. OE-quality modules are critical; cheap aftermarket units fail quickly. Replace fuel filter at same time.

Estimated cost: $700-1,100

Symptoms: Clicking or ticking noise from behind the dash, Heat blows cold or A/C blows hot, no temp control, Airflow stuck on defrost or floor vents, Noise stops when ignition is cycled but returns

Fix: Multiple actuators control blend doors; they fail and make constant clicking noise. Most are accessible under the dash with 1-2 hours labor each. The worst one requires partial dash removal (4-6 hours). Common failure; plan on replacing all eventually.

Estimated cost: $250-800