2008 GMC T7500

The 2008 GMC T7500 is a medium-duty truck often used for commercial purposes like delivery, construction, and utility work. Engine options for this model year include the Duramax 6.6L diesel engine (rated around 300-330 hp and 520-620 lb-ft of torque, depending on the specific tune) and the Vortec 8.1L gasoline engine (rated around 325 hp and 440 lb-ft of torque). The most common transmission choices were the Allison 1000 series automatic. Owners appreciate the T7500’s robust build and hauling capacity, but common complaints revolve around maintenance costs, diesel engine emissions systems, and the overall ride quality.

Engine

Duramax 6.6L Diesel

• Fuel Injector Failure
  • Description/Symptoms: Rough running engine, misfires, white smoke from exhaust, decreased fuel economy. Often affects injectors due to high-pressure fuel system issues or contaminated fuel.
  • Solution: Replacement of faulty fuel injectors. Diagnose and repair the cause of injector failure (e.g., fuel contamination, high-pressure fuel pump failure).
  • Estimated Cost to Fix: $400 - $800 per injector (parts and labor).
  • Recalls: None Found
• EGR Valve Failure
  • Description/Symptoms: Check engine light, reduced engine power, poor fuel economy, excessive black smoke. EGR valve can become clogged with carbon deposits, preventing proper operation.
  • Solution: Cleaning or replacement of the EGR valve. Inspect and clean the EGR cooler.
  • Estimated Cost to Fix: $200 - $500 (parts and labor).
  • Recalls: None Found
• Turbocharger Issues
  • Description/Symptoms: Loss of power, black smoke, unusual turbo noises, check engine light. Issues can range from wastegate problems to complete turbo failure.
  • Solution: Diagnosis of turbocharger and related components. Repair or replacement of the turbocharger.
  • Estimated Cost to Fix: $1500 - $3000+ (parts and labor).
  • Recalls: None Found

Vortec 8.1L Gasoline

• Intake Manifold Gasket Leak
  • Description/Symptoms: Coolant leak, rough idle, misfires, check engine light. The plastic intake manifold gaskets can degrade and leak over time.
  • Solution: Replacement of the intake manifold gaskets.
  • Estimated Cost to Fix: $400 - $800 (parts and labor).
  • Recalls: None Found
• Oil Consumption
  • Description/Symptoms: Excessive oil consumption, blue smoke from the exhaust.
  • Solution: Diagnosis of cause (worn valve seals, piston rings, etc.). Repair or replacement of affected components.
  • Estimated Cost to Fix: $800-$4000+ depending on the cause.
  • Recalls: None Found

Transmission

Allison 1000 Series Automatic

• Torque Converter Issues
  • Description/Symptoms: Shuddering during acceleration, poor fuel economy, slipping, overheating.
  • Solution: Replacement of the torque converter.
  • Estimated Cost to Fix: $800 - $2000 (parts and labor).
  • Recalls: None Found
• Shift Solenoid Failure
  • Description/Symptoms: Erratic shifting, harsh shifts, failure to shift, transmission stuck in gear.
  • Solution: Replacement of faulty shift solenoids.
  • Estimated Cost to Fix: $300 - $800 (parts and labor).
  • Recalls: None Found
• Internal Seal Leaks
  • Description/Symptoms: Transmission fluid leaks, slipping, poor shifting.
  • Solution: Replacement of seals. Complete transmission rebuild may be necessary in severe cases.
  • Estimated Cost to Fix: $500 - $3000+ (parts and labor).
  • Recalls: None Found

Suspension

• Leaf Spring Sagging/Failure
  • Description/Symptoms: Vehicle sagging, poor ride quality, reduced load capacity. Leaf springs can weaken or break over time, especially with heavy use.
  • Solution: Replacement of leaf springs.
  • Estimated Cost to Fix: $500 - $1500 per axle (parts and labor).
  • Recalls: None Found
• Worn Shocks/Struts
  • Description/Symptoms: Bouncy ride, poor handling, excessive body roll.
  • Solution: Replacement of shocks/struts.
  • Estimated Cost to Fix: $200 - $600 per axle (parts and labor).
  • Recalls: None Found

Electrical

• Wiring Harness Issues
  • Description/Symptoms: Intermittent electrical problems, lights flickering, sensors malfunctioning. Wiring can become corroded or damaged, especially in harsh environments.
  • Solution: Diagnosis and repair of damaged wiring. Replacement of damaged harnesses.
  • Estimated Cost to Fix: $100 - $1000+ (depends on the severity and location of the issue).
  • Recalls: None Found
• Alternator Failure
  • Description/Symptoms: Dim lights, dead battery, charging system warning light.
  • Solution: Replacement of the alternator.
  • Estimated Cost to Fix: $300 - $600 (parts and labor).
  • Recalls: None Found
• Body Control Module (BCM) Issues
  • Description/Symptoms: Intermittent electrical problems, issues with power windows, locks, or lights.
  • Solution: BCM reprogramming or replacement.
  • Estimated Cost to Fix: $300-$1000 (parts and labor).
  • Recalls: None Found

Exterior

• Rust
  • Description/Symptoms: Rust forming on body panels, frame, and undercarriage.
  • Solution: Repair or replacement of rusted components. Rust proofing.
  • Estimated Cost to Fix: $100 - $5,000+ (depends on severity)
  • Recalls: None Found
• Headlight Clouding/Yellowing
  • Description/Symptoms: Reduced headlight brightness and visibility.
  • Solution: Headlight restoration or headlight replacement.
  • Estimated Cost to Fix: $25 - $200.
  • Recalls: None Found

Interior

• HVAC Issues
  • Description/Symptoms: Weak airflow, no heat, no AC, strange noises from the HVAC system. Problems can range from a faulty blower motor to a clogged evaporator core.
  • Solution: Diagnosis of the HVAC system and replacement of faulty components.
  • Estimated Cost to Fix: $100 - $1000+ (depends on the issue).
  • Recalls: None Found
• Instrument Cluster Issues
  • Description/Symptoms: Gauges not working, backlighting failure, information display problems.
  • Solution: Repair or replacement of the instrument cluster.
  • Estimated Cost to Fix: $200 - $800 (parts and labor).
  • Recalls: None Found

Summary

The 2008 GMC T7500 is a workhorse, but owners should be aware of potential issues, particularly with the diesel engine emissions systems and the Allison transmission. Engine-related issues can be costly, especially fuel injector and turbocharger failures on the Duramax, and intake manifold leaks and oil consumption on the Vortec. Transmission problems like torque converter issues and shift solenoid failures can also be expensive to fix. Suspension wear is expected on a truck of this age and duty, and electrical gremlins can be frustrating. Rust can also be a significant issue. Overall, potential buyers should carefully inspect the vehicle’s maintenance history and consider a pre-purchase inspection to identify any existing or potential problems.