2004 GMC Sierra 2500 HD

The 2004 GMC Sierra 2500 HD is a popular heavy-duty truck known for its towing capacity and reliability. Engine options included the 6.0L Vortec V8 (300 hp, 360 lb-ft of torque), the 8.1L Vortec V8 (340 hp, 455 lb-ft of torque), and the 6.6L Duramax Diesel V8 (300 hp, 520 lb-ft of torque). Transmission options were the 4L80E four-speed automatic (with the 6.0L gas engine) and the Allison 1000 five-speed automatic (with the 8.1L gas engine and the 6.6L Duramax diesel). Owners generally appreciate the truck’s ruggedness and capabilities, but some common complaints involve electrical gremlins and driveline issues, especially as the vehicles age.

Engine

6.0L Vortec V8

• Oil Pressure Sensor Failure
  • Description/Symptoms: The oil pressure gauge reads incorrectly (often showing zero or maximum pressure) and/or the “check gauges” light illuminates.
  • Solution: Replace the oil pressure sensor.
  • Estimated Cost to Fix: $50 - $150
  • Recalls: None Found
• Intake Manifold Gasket Leak
  • Description/Symptoms: Coolant leak, rough idle, engine misfire, or coolant smell.
  • Solution: Replace the intake manifold gaskets.
  • Estimated Cost to Fix: $300 - $600
  • Recalls: None Found

8.1L Vortec V8

• Exhaust Manifold Bolts Breaking
  • Description/Symptoms: Exhaust leak noise (ticking or hissing), reduced fuel economy.
  • Solution: Replace the broken exhaust manifold bolts and possibly the exhaust manifold if warped.
  • Estimated Cost to Fix: $300 - $800+
  • Recalls: None Found
• Oil Consumption
  • Description/Symptoms: Excessive oil consumption requiring frequent top-offs.
  • Solution: In some cases, a PCV valve replacement may help. If severe, piston rings or valve seals may need replacement.
  • Estimated Cost to Fix: $100 (PCV valve) to $2000+ (major engine work)
  • Recalls: None Found

6.6L Duramax Diesel V8 (LB7)

• Fuel Injector Failure
  • Description/Symptoms: Rough idle, white smoke, decreased fuel economy, hard starting.
  • Solution: Replace the faulty fuel injectors.
  • Estimated Cost to Fix: $2000 - $4000 (for all injectors)
  • Recalls: Recall # 04036 (N030201): Injector Replacement - This recall covered specific VIN ranges and involved replacing faulty fuel injectors.
• Glow Plug Failure
  • Description/Symptoms: Hard starting, especially in cold weather, and/or white smoke.
  • Solution: Replace the faulty glow plugs.
  • Estimated Cost to Fix: $200 - $500
  • Recalls: None Found

Transmission

4L80E Four-Speed Automatic

• Harsh Shifting
  • Description/Symptoms: Hard or erratic shifting between gears.
  • Solution: Check and replace the transmission fluid. If problem persists, the valve body may need to be rebuilt or replaced, or the transmission needs to be rebuilt
  • Estimated Cost to Fix: $100 (fluid) to $800+ (valve body/rebuild)
  • Recalls: None Found

Allison 1000 Five-Speed Automatic

• Torque Converter Clutch (TCC) Slipping
  • Description/Symptoms: Engine RPM fluctuates at highway speeds while under load.
  • Solution: Often requires transmission rebuild or replacement of the torque converter.
  • Estimated Cost to Fix: $2500 - $5000
  • Recalls: None Found
• Loss of 4th and 5th Gear
  • Description/Symptoms: Transmission will not shift into 4th or 5th gear.
  • Solution: Usually requires a transmission rebuild, with specific attention to the clutch packs for the higher gears.
  • Estimated Cost to Fix: $2500 - $5000
  • Recalls: None Found

Suspension

• Pitman Arm/Idler Arm Wear
  • Description/Symptoms: Loose steering, wandering on the road, clunking noises from the front end.
  • Solution: Replace the pitman arm, idler arm, and possibly the associated hardware.
  • Estimated Cost to Fix: $300 - $600
  • Recalls: None Found
• Torsion Bar Sag
  • Description/Symptoms: Front end sits lower than normal, reduced ride quality, and potentially rubbing tires.
  • Solution: Adjust the torsion bar keys or replace the torsion bars if they have weakened.
  • Estimated Cost to Fix: $100 - $400
  • Recalls: None Found

Electrical

• Instrument Cluster Issues
  • Description/Symptoms: Gauges malfunctioning, flickering, or completely inoperative.
  • Solution: Instrument cluster repair or replacement.
  • Estimated Cost to Fix: $200 - $600
  • Recalls: None Found
• Body Control Module (BCM) Problems
  • Description/Symptoms: Intermittent electrical issues, such as malfunctioning power windows, door locks, or lighting.
  • Solution: BCM reprogramming or replacement.
  • Estimated Cost to Fix: $300 - $800
  • Recalls: None Found

Exterior

• Rust on Rocker Panels and Cab Corners
  • Description/Symptoms: Visible rust forming on the lower portions of the cab.
  • Solution: Rust repair or panel replacement.
  • Estimated Cost to Fix: $500 - $2000+ (depending on severity)
  • Recalls: None Found

Interior

• Dashboard Cracking
  • Description/Symptoms: Cracks appearing on the dashboard, especially in sun-exposed areas.
  • Solution: Dashboard replacement or use of a dashboard cover.
  • Estimated Cost to Fix: $400 - $1200 (replacement)
  • Recalls: None Found

The 2004 GMC Sierra 2500 HD presents a mix of potential issues. The Duramax diesel can face expensive injector problems, while gas engines might suffer from oil consumption or exhaust leaks. Transmission issues, particularly with the Allison, can be costly. Electrical gremlins and rust are also common concerns. Overall, while a capable truck, potential buyers should be aware of these possible maintenance costs when considering this model.