The John Deere 316, 318, and 420 Lawn and Garden Tractors Service Technical Manual (TM1590) is your comprehensive guide to maintaining and repairing these popular models. This detailed manual covers every aspect of these tractors, providing step-by-step instructions and highly detailed exploded diagrams to ensure you complete each job correctly and efficiently.

This manual is designed for both experienced mechanics and do-it-yourself enthusiasts. It is organized into clear sections addressing specific areas of the tractor, including:

* **General Information:** Covers safety procedures, general specifications, repair specifications, test and adjustment specifications, fuels and lubricants, and serial number location.
* **Engine Repair:** Provides detailed information on the engine, including disassembly, reassembly, and troubleshooting.
* **Electrical Repair:** Covers the front PTO clutch and related electrical components.
* **Power Train Repair:** Delves into the transmission, transmission control linkage, differential, rear axles, drive shaft, and other power train components.
* **Steering and Brake Repair:** Covers the steering systems for both the 316 and the 318/420 models, as well as brake systems.
* **Hydraulic Repair:** Provides guidance on the hydraulic control valve.
* **Miscellaneous Repair:** Addresses the front axle, mower spindle and jack sheave repairs, and mower gear case repair.
* **Engine, Fuel and Air System Checkout and Diagnosis:** Offers procedures for checking, diagnosing, and adjusting the engine, fuel, and air systems.
* **Electrical Checkout, Operation and Diagnosis:** Explains the electrical system, provides schematics, details component location and operation, and guides you through diagnosis and testing.
* **Power Train Checkout, Operation and Diagnosis:** Covers the power train system, its theory of operation, and provides diagnosis, testing, and adjustment procedures.
* **Steering and Brakes Checkout, Operation and Diagnosis:** Covers the steering and braking systems, their operation, and includes diagnosis, testing, and adjustment procedures.
* **Hydraulic System Checkout, Operation and Diagnosis:** Offers information on the hydraulic system, provides schematics, explains its theory of operation, and guides you through diagnosis, testing, and adjustment.
* **Dealer Fabricated Tools:** Includes a section on tools commonly used by John Deere dealers.
* **Index:** Provides a comprehensive index for easy reference.

This manual is your ultimate resource for keeping your John Deere 316, 318, or 420 lawn and garden tractor in tip-top shape.