Toyota 2H and 12H-T 4.0 Litre 6 Cylinder Diesel Factory Engine Rebuild Manual | PDF Download

The Toyota 2H and 12H-T engines are legendary for their durability and reliability, powering a range of iconic Toyota vehicles, primarily the Land Cruiser series. For owners and mechanics alike, understanding and maintaining these engines is crucial. This serves as an overview of what the comprehensive manual for these engines entails, offering insights into its structure and key components.

HOW TO USE THIS MANUAL

This section is critical. It explains the manual's organization, how to locate specific information, and the conventions used, such as symbols and warnings. 

IDENTIFICATION INFORMATION

Detailed information on engine identification is paramount. This section outlines how to identify the engine type,  through engine codes and serial numbers. This helps ensure the correct parts are ordered and that the manual is being used for the appropriate engine variant.

GENERAL REPAIR INSTRUCTIONS

A section dedicated to general repair instructions provides fundamental guidance. This includes safety precautions, cleanliness standards, proper tool usage, and torquing techniques. It sets the foundation for successful repairs and prevents potential damage to the engine or injury to the mechanic.

ABBREVIATIONS USED IN THIS MANUAL

A comprehensive list of abbreviations used throughout the manual is essential for clear understanding. Common mechanical terms, acronyms for components, and units of measurement, allowing users to quickly decipher technical information.

ENGINE MECHANICAL

This section delves into the core of the engine. It covers procedures for disassembly, inspection, repair, and reassembly of all mechanical components, including:

• Cylinder Head Rebuild: Step-by-step instructions on valve grinding, seat replacement, and head resurfacing.

• Timing Gears and Camshaft: Procedures for timing gear alignment, camshaft inspection, and replacement.

• Cylinder Block Rebuild: Instruction on honing cylinders, piston installation, and crankshaft bearing replacement.

DIESEL ENGINE DIAGNOSIS and Diagnostics Sections

Comprehensive diagnostic procedures for both the Diesel Electrical System and the Turbocharger are explained in detail with troubleshooting guides for:

• Diesel Engine Diagnosis

• Diesel Electrical System Diagnosis [2H]

• Diesel Electrical System Diagnosis [12H-T]

• Turbocharger Diagnosis [12H-T]

• Turbocharger Electrical System Diagnosis [12H-T]

ENGINE TUNE-UP

This section details the procedures to optimize engine performance. Contents include fuel injection timing, valve adjustments, and idle speed settings.

COMPRESSION CHECK

Step-by-step guides on performing compression tests on both the 2H and 12H-T engines are given to evaluate engine health.

FUEL SYSTEM

Detailed instructions for servicing the fuel system, covering everything from the Replacement of Fuel Filter to overhauling the Injection Pump. Important sections include:

• Injection Nozzles: Inspection, cleaning, and testing procedures for both 2H and 12H-T engines.

• Fuel Feed Pump: Instructions for testing and replacing the fuel feed pump.

• Automatic Timer: Explanation of the automatic timer function and adjustment procedures.

COOLING SYSTEM

The manual covers the cooling system's components, covering troubleshooting, Check and Replacement of Engine Coolant, and procedures for servicing the Water Pump, Thermostat, and Radiator.

LUBRICATION SYSTEM

This section details the oiling system, including Troubleshooting, perform Oil Pressure Check, Replacement of Engine Oil and Oil Filter, repairing the Oil Pump, Oil Cooler and Relief Valve, and the Oil Nozzles and Check Valves in the 12H-T engine.

STARTING SYSTEM

This part of the manual explains Pre-Heating System for both engines, Troubleshooting, Starting System Circuit and repair and replacement for the Starter and Starter Relay.

ELECTRICAL DIESEL INJECTION CONTROL (EDIC) SYSTEM

Explains the EDIC system and its variations for the 2H and 12H-T engines and adjustment procedures

CHARGING SYSTEM

Diagnosing and servicing the charging system is covered, including Troubleshooting, Charging System Circuit, On-Vehicle Inspection, and repair or replacement of the Alternator, Alternator Regulator, and Charge Light Relay.

SERVICE SPECIFICATIONS

A comprehensive table listing all critical measurements, tolerances, and settings for each engine component. This is essential for ensuring proper reassembly and optimal engine performance.

SST AND SSM

Lists SST (Special Service Tools) and SSM (Special Service Materials) required for specific tasks. These tools and materials are often necessary for accurate and efficient repairs.

STANDARD BOLT AND TORQUE SPECIFICATIONS

A chart detailing the torque values for all standard bolts used throughout the engine. Proper torque is crucial for preventing leaks and ensuring structural integrity.

By following this comprehensive manual, mechanics and owners can confidently tackle repairs, maintenance, and even complete rebuilds of these robust Toyota diesel engines, ensuring their continued reliability for years to come.

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