1986–1990 John Deere 70 Excavator Repair, Operation & Tests Manual (TM1376)

John Deere technical manual TM1376, revised 20MAR90, covers repair, operation and testing for the 1986–1990 John Deere 70 excavator, including standard and offset boom configurations and machines equipped with a dozer blade.

• Engine service: Engine and cylinder head removal and installation, fuel injection pump static timing, valve adjustment, and cooling-system testing.
• Tracks and propel drive: Roller wear checks, front-idler inspection, track adjuster and recoil spring service, plus travel gearbox and park-brake repair.
• Hydraulic repair: Main and pilot pump service, control-valve repair, boom, arm and bucket cylinder overhaul, and hydraulic cylinder air bleeding.
• System diagnosis: Operational checkout charts, pressure and flow tests, cylinder drift diagnosis, and main pump regulator engine pulldown tests.
• Swing system: Swing motor and gearbox overhaul, swing-lock and crossover-relief valve service, and performance checks for rotation faults.
• Electrical troubleshooting: Starting motor and alternator testing, charging-system wiring, and point-by-point checks of monitor gauges and indicator circuits.

Written for experienced technicians, this manual specifies the service tools and test equipment required for the work.

Engine, Fuel Injection and Cooling

Engine service scope: The 4-239D chapters cover engine and cylinder head removal and installation, plus fuel transfer pump replacement. Cooling-system procedures address the water pump, thermostat, radiator and oil cooler. Complete engine repair requires the separate component technical manual CTM-4.

Fuel injection: Pump removal, installation, static timing and fuel-system bleeding are covered. Internal pump repair or adjustment is assigned to an authorized fuel injection service center; nozzle testing and repair refer to TM-1214. Neither referenced manual is included. The pump removal procedure warns that turning the outlet fittings can damage the pump internally.

Undercarriage and Travel Drive Repair

Upper and lower roller wear limits and front-idler inspections support undercarriage assessment. Upper roller cross sections and track adjuster exploded views accompany repair instructions. Recoil spring work uses dedicated equipment, with fabrication drawings for ST4920 and DFT1087.

Travel gearbox, park brake, travel motor, counterbalance valve and rotary manifold sections cover disassembly and assembly. Safety guidance addresses blocking the excavator, stored recoil-spring energy and pressure release before hydraulic service.

Pump Control and Attachment Hydraulics

Pump control: Main pump, pilot pump, switch valve and flow combiner valve coverage connects component repair with circuit operation. Hydraulic diagrams show combined swing/arm and swing/travel operation. Regulator engine pulldown tests check how pump load affects engine speed.

Leakage diagnosis: The boom, arm and bucket drift test distinguishes control-valve leakage from cylinder leakage, helping identify which assembly needs further repair work. Cylinder bleeding instructions address pump damage from trapped air and seal damage from sudden cylinder movement.

Configuration references: Offset boom and dozer blade circuits receive separate coverage. Working-range charts and lift-capacity tables distinguish boom, arm and blade configurations.

Electrical Tests and Shop References

Starting motor tests cover the armature, field windings and no-load performance; alternator checks address the rotor, stator and diodes. Charging-system wiring diagrams and monitor-circuit schematics connect electrical tests with harness connections.

Reference tables cover customary and metric fastener torques, flared fluid fittings, and lubricant viscosity recommendations for hydraulic, gear and engine components across ambient temperatures.

A Preview of Refill Data and Valve Clearances

These refill and valve-clearance figures are a small sample of the manual’s service data.

The drain-and-refill table lists 11.4 L (12 qt) for the cooling system and 60 L (15.8 gal) for the hydraulic reservoir.

For the 4-239D engine, intake valve clearance is 0.36 mm (0.014 in.) and exhaust valve clearance is 0.46 mm (0.018 in.); the adjustment procedure permits a hot or cold engine.

PDF Navigation, Diagrams and Page Count

Text search and diagram detail: Embedded OCR supports searches through most text sections, and PDF bookmarks link to system sections and individual procedures. Some diagram and theory pages have no searchable text. Small wiring labels need zooming; fine lines in some hydraulic foldouts are faint.

One printable, 534-page PDF in English: six front-matter pages, 526 pages of safety, technical sections and tool drawings, and two closing pages. The total already includes the cover, foreword, revision notice, contents pages, blank dividers and rear safety page.