1990 John Deere 490 Excavator Repair, Operation & Tests Manual (TM1302)

John Deere technical manual TM1302, revised March 20, 1990, covers repair, operation, and tests for the 1984–1990 John Deere 490 Excavator.

• Engine repair: Crankshaft, camshaft, connecting rod, piston, cylinder block, cylinder head, and engine balancer inspection and repair.

• Engine support systems: Injection-pump removal, installation, timing, and bleeding; turbocharger overhaul; water-pump and oil-cooler service.

• Tracks and travel drives: Track-chain repair, recoil-spring service, axle and bearing work, planetary gearbox disassembly and assembly, and travel-motor overhaul.

• Working hydraulics: Main-pump and control-valve disassembly and assembly, hydraulic-cylinder inspection and resealing, and air-bleeding procedures.

• Swing system: Separate gearbox, motor, and valve procedures for the serial-number variants, plus swing-bearing seal replacement.

• System testing and electrical: Operational checkout, engine and hydraulic diagnostics, motor leakage tests, monitor troubleshooting, starter tests, and electrical wiring schematics.

This manual is written for experienced technicians and identifies the essential service tools needed for specific jobs.

Engine, Fuel Injection, and Cooling

Internal engine work includes valve-clearance adjustment, timing-gear installation, and cylinder-liner inspection. Turbocharger repair includes radial and axial bearing checks and a component wear-tolerance chart.

Injection system: The Roosa-Master Model DM pump coverage includes static timing and timing-advance adjustment. Injection-nozzle removal, seal replacement, and installation are included; internal pump repair and nozzle testing/repair are referred to TM1109, a separate publication not included in this PDF.

The pump-removal section explains how turning the outlet fittings while disconnecting injection lines can damage the pump internally.

Cooling and lubrication coverage adds thermostat testing, water-pump rebuilding, and oil-cooler bypass-valve inspection.

Track, Travel, and Swing Service

Track specifications distinguish new dimensions, recommended service limits, and limits of use. The recoil-spring procedure uses ST4920 and DFT1087, with tool fabrication drawings in Section 99.

Travel-drive sections cover axle shafts, bearings, and reduction gears, including floating seals, planetary carriers, and the spring-set, hydraulically released parking brake.

Swing variants: Separate swing-gearbox cross sections and motor repair procedures cover machine S/N up to 9733 and 9734 and up, including the earlier lock valve and later swing valve. This helps technicians match the component design before selecting inspection criteria or assembly instructions.

The general specifications distinguish standard and optional arms and track shoes, with separate lift-capacity tables for the arm configurations.

Follow the manual's pressure-release and machine-support precautions before servicing hydraulic components or the heavily preloaded track recoil spring.

Hydraulic Fault Finding and Electrical Checks

Main pump: The repair procedure treats each rotary group as a replacement assembly and keeps it paired with its regulator.

Hydraulic schematics trace the flow combiner valve, pressure controllers, and make-up valves through individual and combined functions. Main-pump regulator cutaways and self-pump/partner-pump P-Q curves explain displacement control under changing loads.

Troubleshooting charts address slow functions, load drift, weak swing, and mistracking. Related checks cover pilot pressure, pump regulators, circuit relief valves, the propel crossover relief valve, and motor leakage to help distinguish control faults from internal leakage before teardown.

The cylinder-bleeding section warns that trapped air can damage pump components and rapid cylinder movement can burn seals.

Electrical component drawings, the wiring schematic, and monitor troubleshooting flowcharts support checks of the hourmeter, temperature gauge, fuel gauge, and warning circuits. Terminal numbers and wire-color codes are included.

Reference tables cover general cap-screw torques, O-ring boss and 37-degree flare connections, lubrication requirements, and metric/U.S. unit conversions.

A Preview of Track and Travel-Drive Specifications

These examples are a small selection of the manual's dimensional and assembly specifications.

New track-pin diameter is listed as 33.5 mm (1.32 in.). For travel-motor assembly, drive-disk rotating torque is 8.63 ± 0.5 N·m. The travel gearbox's carrier-to-drum cap screws are specified at 265 N·m (195 lb-ft).

PDF Search, Navigation, and Page Count

Search and diagram detail: Text search is available across much of the manual, with OCR gaps on several diagram pages. Embedded PDF bookmarks link sections and component topics. Small electrical labels need zooming; some hydraulic schematic labels remain faint and difficult to read even when enlarged.

One printable 638-page PDF contains the repair and operation/test sections and tool drawings. The total includes two cover pages, one foreword page, one revision-notice page, and 37 blank or header/footer-only pages; these are already included in the page count.