2000 GMC T6500

The 2000 GMC T6500 is a medium-duty truck often used for commercial applications like delivery, utility work, and landscaping. Engine options include the Caterpillar 3126 diesel engine, the Duramax 7.8L diesel engine, and the Vortec 8.1L gas engine. Transmission options often include Allison automatic transmissions, such as the AT545. The Caterpillar 3126 produces around 175-330 horsepower and 420-860 lb-ft of torque depending on the specific configuration. People often appreciate the T6500 for its reliability, ease of maintenance (compared to newer trucks), and straightforward design. Common dislikes include rough ride, limited features, and fuel economy (especially with gas engines).

Engine

Caterpillar 3126 Diesel Engine

• Injector Failure
  • Description/Symptoms: Rough idling, poor fuel economy, excessive black smoke, and eventual engine misfire or no-start condition.
  • Solution: Replace faulty injectors with new or remanufactured units. Ensure proper fuel pressure and filter maintenance to prevent recurrence.
  • Estimated Cost to Fix: $500 - $2,000+
  • Recalls: None Found
• HEUI (Hydraulic Electronic Unit Injector) Pump Failure
  • Description/Symptoms: Loss of power, hard starting, stalling, and eventual no-start condition. The HEUI pump provides high-pressure oil to actuate the fuel injectors.
  • Solution: Replace the HEUI pump. Check oil quality and pressure to ensure proper HEUI system operation.
  • Estimated Cost to Fix: $800 - $3,000+
  • Recalls: None Found
• Turbocharger Failure
  • Description/Symptoms: Whining noise from the turbocharger, loss of power, excessive black smoke, and increased oil consumption.
  • Solution: Replace or rebuild the turbocharger. Check for oil leaks and address any underlying issues causing premature turbo failure.
  • Estimated Cost to Fix: $1,000 - $4,000+
  • Recalls: None Found

Duramax 7.8L Diesel Engine

• Injector Failure
  • Description/Symptoms: Rough idling, poor fuel economy, excessive black smoke, and eventual engine misfire or no-start condition.
  • Solution: Replace faulty injectors with new or remanufactured units. Ensure proper fuel pressure and filter maintenance to prevent recurrence.
  • Estimated Cost to Fix: $500 - $2,000+
  • Recalls: None Found
• Turbocharger Failure
  • Description/Symptoms: Whining noise from the turbocharger, loss of power, excessive black smoke, and increased oil consumption.
  • Solution: Replace or rebuild the turbocharger. Check for oil leaks and address any underlying issues causing premature turbo failure.
  • Estimated Cost to Fix: $1,000 - $4,000+
  • Recalls: None Found

Vortec 8.1L Gas Engine

• Intake Manifold Gasket Leak
  • Description/Symptoms: Coolant leak, rough idle, engine misfires, and possible overheating.
  • Solution: Replace the intake manifold gaskets.
  • Estimated Cost to Fix: $300 - $800+
  • Recalls: None Found
• Oil Consumption
  • Description/Symptoms: Excessive oil consumption with no visible leaks. May be caused by worn valve stem seals or piston rings.
  • Solution: Replace valve stem seals or rebuild the engine if piston rings are worn.
  • Estimated Cost to Fix: $500 - $5,000+
  • Recalls: None Found

Transmission

Allison AT545 Automatic Transmission

• Slipping or Delayed Shifts
  • Description/Symptoms: The transmission hesitates to shift or slips during gear changes. This can be caused by worn clutch packs or valve body issues.
  • Solution: Rebuild or replace the transmission. Repair the valve body.
  • Estimated Cost to Fix: $1,500 - $5,000+
  • Recalls: None Found
• Hard Shifting
  • Description/Symptoms: Abrupt and harsh shifts, especially between gears. This can be caused by a faulty modulator valve, worn transmission mounts, or internal component damage.
  • Solution: Replace or repair the modulator valve. Replace worn transmission mounts. Rebuild or replace the transmission if internal damage is present.
  • Estimated Cost to Fix: $100 - $5,000+
  • Recalls: None Found

Suspension

• Leaf Spring Sagging or Breakage
  • Description/Symptoms: The truck sits lower on one side, or a leaf spring is visibly cracked or broken. This can affect ride quality and handling.
  • Solution: Replace the affected leaf spring(s).
  • Estimated Cost to Fix: $200 - $1,000+ per spring.
  • Recalls: None Found
• Worn Shocks/Struts
  • Description/Symptoms: Bouncy ride, poor handling, and excessive body roll.
  • Solution: Replace worn shocks/struts.
  • Estimated Cost to Fix: $100 - $500+
  • Recalls: None Found

Electrical

• Wiring Harness Issues
  • Description/Symptoms: Intermittent electrical problems, such as lights flickering, gauges malfunctioning, or starting issues. This is common in older trucks due to corrosion and wear.
  • Solution: Inspect and repair damaged wiring harnesses. Replace corroded connectors.
  • Estimated Cost to Fix: $100 - $1,000+
  • Recalls: None Found
• Alternator Failure
  • Description/Symptoms: Dimming lights, slow engine cranking, and eventually a no-start condition.
  • Solution: Replace the alternator.
  • Estimated Cost to Fix: $200 - $500+
  • Recalls: None Found

Exterior

• Rust
  • Description/Symptoms: Rust forming on the frame, body panels, and undercarriage.
  • Solution: Treat affected areas with rust converter, repair or replace rusted panels.
  • Estimated Cost to Fix: $100 - $1,000+
  • Recalls: None Found

Interior

• Cracked Dashboard
  • Description/Symptoms: Cracks appearing on the dashboard due to age and sun exposure.
  • Solution: Replace the dashboard or install a dashboard cover.
  • Estimated Cost to Fix: $100 - $1,000+
  • Recalls: None Found

Summary

The 2000 GMC T6500, while generally reliable, can suffer from common issues associated with medium-duty trucks of that era. Engine issues, especially injector and turbocharger problems in the diesel variants, can be costly. Transmission problems, particularly slipping or hard shifting, also represent a significant potential expense. Suspension wear and tear, along with electrical gremlins, are also common. While some fixes are relatively inexpensive, major engine or transmission repairs can easily run into the thousands of dollars. Potential buyers should thoroughly inspect the truck, paying close attention to engine performance, transmission behavior, and any signs of rust or electrical problems.