GM 6.6L Duramax Diesel V-8 Engines: How to Rebuild and Modify

By the late 1990s, General Motors realized that its old Detroit Diesel engine, which had been designed 20 years earlier, was due for a major update. The Detroit Diesel engine was never intended to be a serious horsepower or torque monster. It was just a steady and reliable workhorse that made credible power, met emissions standards, and achieved decent fuel economy. As Ford and Dodge released new designs of their Power Stroke and Cummins engines, respectively, General Motors needed to follow suit.

The first Duramax engine made its debut in 2001. Over the last 25 years, several versions were introduced, all displacing 6.6L and all producing ever-increasing horsepower, torque, and efficiency. As with any engine that is more than two decades old, many now need a complete overhaul. In GM 6.6L Duramax Diesel V-8 Engines: How to Rebuild and Modify, all aspects of a rebuild are covered in simple step-by-step fashion with more than 375 color photos. A brief history is provided, followed by diagnosis, engine removal, and disassembly procedures, which include the special tools that are required. Next are inspection and machine work, which are followed by reassembly and reinstallation. Finally, a performance chapter is included with commentary by Gale Banks.

Whether you want to tackle this project yourself or just want to know how it all works, this guide will help you along the way.

Table of Contents:

Chapter 1:

• History and Operation 
• RPO Code 
• First Generation (LB7)
• Second Generation (LLY)
• Third Generation (LBZ)
• Fourth Generation (LMM)
• Fifth Generation (LML)
• Sixth Generation (L5P)
• The “Other” Duramax Engines
• Engine Identification
• Lubrication System
• Cooling System
• Turbocharger System
• Glow-Plug System
• Crankcase Ventilation System
• EGR Electronic Throttle Valve
• The HPCR Fuel-Injection System

 Chapter 2:

• Engine Removal

Chapter 3:

• Special Tools
• Precision Measuring Tools
• Valve-Spring Compressor
• Electronically Controlled Cooling Fan
• Engine Disassembly
• Glow Plugs

Chapter 4:

• Engine Block Cleaning, Inspection, and Service
• Engine-Mount Hole Thread Inspection
• Freeze/Cup Plug Installation
• Camshaft and Bearing Inspection
• Camshaft Bearing Removal
• Oil Cooling Nozzle Removal
• Cylinder Bores
• Valvetrain Component Inspection 68 Crankshaft and Bearing Cleaning and Inspection
• Crankshaft Bearing Selection
• Injector Cleaning
• Cylinder-Head Disassembly and Inspection
• Valve-Guide Measurement, Reaming, and Valve Grinding
• Glow-Plug Bores
• Balancer
• Oil Pan
• Intake Manifold
• Flywheel Housing
• Front Cover
• Piston and Ring Inspection
• Connecting Rods

• Measure the Camshaft Endplay
• Engine Oil-Pressure Sensor
• Engine Reinstallation

 Chapter 6:

• 2024 L5P Pistons
• 2024 L5P Head Gasket
• 2024 L5P Piston Cooling Nozzle
• Crankshaft
• Cylinder Heads and Valve Springs 105
• L5P Turbocharger
• L5P Denso Fuel System 2017–Current
• Fuel-Rail Pressure Sensor
• Fuel-Level Sensor
• In-Tank Lift Pump
• High-Pressure Fuel Pump
• L5P Solenoid Fuel Injector
• Piezoelectricity
• Fuel Rails
• Engine Management
• Fuel-Injection Control Module
• DTC Retrieval and ECM Communication
• Misfire Detection and Cylinder Balance Analysis
• Injector Replacement and Calibration Codes
• Cylinder Balance Test: Related DTC Not Set
• Cylinder Firing Groups
• E35 Bosch ECM
• Sensor Overview
• Exhaust Aftertreatment System
• DPF Regeneration
• Selective Catalyst Reduction System
• Engine Diagnosis Cases
• Return Volume Test for High-Pressure System
• Duramax Engine Oil Checks
• Method to Check for Fluid in Oil
• Engine Oil
• Oil Filter
• Fuel Leaks