Komatsu WA300-1, WA320-1 Wheel Loader 1988–1994 Shop Manual (P/N SEBM04190107)

Komatsu shop manual P/N SEBM04190107 covers the 1988–1994 WA300-1 and WA320-1 wheel loaders, serial number 10001 and up, with separate procedures and specifications for documented production changes.

PDF Bookmarks and Wiring Detail

Search, navigation and diagram readability: PDF text search is not available. Embedded bookmarks provide access to the main systems and many individual procedures. Small wiring labels require zooming; some very small wire codes in the later electrical circuit diagram remain difficult to read.

One printable 841-page PDF in English, including the original cover and four pages of revision records.

Engine Checks, Drivetrain Repair and Loader Hydraulics

The following selected coverage highlights outline the main workshop sections. Additional topics include cab removal and optional air-conditioner component replacement.

• Engine diagnosis: Valve-clearance adjustment, compression and blow-by testing, fuel-injection timing checks, oil-pressure measurement, and exhaust-color evaluation.

• Powertrain repair: Torque-converter, transmission, clutch-pack and control-valve disassembly and assembly, plus axle, differential and final-drive inspection standards.

• Steering service: Steering gear box, valve and cylinder repair, linkage adjustment, steering-pressure checks, and center hinge pin removal and installation.

• Brake system: Brake-booster overhaul, piston-leakage and disc-wear checks, brake-line bleeding, and parking-brake inspection and adjustment.

• Work equipment hydraulics: Main control valve and lift/dump cylinder repair, hydraulic-pressure and drift tests, bucket-positioner adjustment, and boom kick-out adjustment.

• Electrical troubleshooting: Starting, stopping, preheating and transmission-control circuits, wiring diagrams, connector terminal views, and Electronic Vehicle Monitoring System fault charts.

Written for service workshop personnel, this manual combines repair procedures with component inspection criteria and dedicated testing-equipment requirements.

Engine Removal, Testing and Installation

Step-by-step removal and installation procedures cover the engine, radiator, cylinder head, fuel injection pump, turbocharger, water pump and nozzle holder. Starter, alternator and engine oil cooler replacement are also covered.

The fuel injection pump and turbocharger sections describe assembly removal and installation, rather than internal overhaul. Engine test tables distinguish bench testing from checks performed with the engine installed.

Cylinder-head installation includes staged tightening specifications that depend on the lubricant used. The rocker-arm installation notes warn that valve-spring load can strain a push rod during assembly.

Transmission Fault Isolation and Differential Setup

The transmission troubleshooting section distinguishes faults in the transmission and control valve from faults in the electrical controls. This supports workshop diagnosis before major assemblies are dismantled.

Serial-specific power-train hydraulic circuit diagrams and electrical transmission control diagrams distinguish the earlier and later systems. Differential assembly instructions include shim selection, bearing preload, backlash adjustment and tooth-contact checks.

Disassembly relationship network drawings show how major removal jobs connect. General assembly and engine assembly drawings provide component orientation alongside the inspection and assembly instructions.

Floating-seal precautions address O-ring scarring from pointed installation tools and seal damage that can lead to oil leakage.

Steering, Brakes and Work Equipment

The steering documentation includes structure, function and maintenance standards for the optional emergency steering pump, diverter valve and security valve.

Two-spool and optional three-spool main control valve configurations have separate circuit diagrams and maintenance-standard tables. Lift-arm and bucket troubleshooting addresses slow movement, weak operation, hydraulic drift and unintended movement when control-lever positions change.

Brake documentation combines hydraulic booster operation with inspection criteria, performance checks and parking-brake pad replacement procedures.

Safe servicing requires the manual’s precautions for articulated-frame locking, supported work equipment, trapped hydraulic pressure and heavy-component lifting.

SA-Series Gear Pump Overhaul

The gear-pump section explains pressure-loaded and fixed-side-plate designs, followed by SA-series disassembly, assembly and clearance inspection. Single, tandem and triple pump arrangements are addressed.

Delivery and post-assembly performance testing use a test bench or flow-meter kit 790-303-1001, with separate standard and repair-limit tables.

Monitoring Systems and Electrical Test Points

Earlier machines use an EVMS auxiliary controller; the later WA300-1 configuration and WA320-1 do not. Separate troubleshooting sections account for this difference.

Wire-color code tables, connector terminal-number views and yes/no diagnostic charts identify the connections and measurements used to distinguish wiring, sensor and monitor-module faults. Speedometer-module adjustment is also included.

A Preview of Engine Adjustment and Cooling Data

For the S6D105-1, the valve-adjustment section specifies cold clearances of 0.25 mm at the intake valves and 0.45 mm at the exhaust valves.

The fuel-injection timing check lists 18° before top dead center with coolant temperature within the operating range. The WA300-1 oil-and-coolant quantity table specifies 38 liters for the engine cooling system.