John Deere JD300-B Loader & Backhoe Service Manual, 1978 (P/N TM-1087)

John Deere technical manual P/N TM-1087 covers the JD300-B Loader and Backhoe Loader, with diesel and gasoline engine service information and separate coverage of 9250 and 9250-A backhoe assemblies. The contents page is dated December 1978; the file also contains revised service pages dated September 1979 and June 1985.

Searchable Service Text and Bookmarked Sections

Search, navigation, and wiring detail: The service text has an OCR search layer, with embedded bookmarks for sections, components, and the index. OCR errors can affect individual searches. Small wiring identifiers and terminal labels are readable with zooming.

Supplied as one printable, English-language PDF with 596 pages, including the front and back covers, two blank pages, and two page-listing sheets. Individual sections can be printed for workshop use.

Engine, Drivetrain, and Loader/Backhoe Service

The following selected contents outline the repair and diagnostic coverage rather than reproduce the full contents list. Other topics include lubrication guidance and predelivery inspections.

• Engine repair: Engine removal, cylinder-head and valve service, wet-liner and piston inspection, crankshaft work, and timing gear train installation.

• Fuel systems: Injection-pump removal, installation, timing, and bleeding, plus nozzle replacement, carburetor repair, governor service, and fuel-system test data.

• Power train: Single- and dual-stage clutch service, collar-shift transmission repair, hydraulic reverser overhaul, continuous-running PTO, differential lock, and planetary final drives.

• Hydraulic components: Transmission and main pump repair, steering and brake valves, loader and backhoe control valves, selective control valve, and rockshaft adjustment.

• Electrical diagnosis: Battery tests, alternator component checks, starter overhaul, gasoline ignition service, gauges, switches, wiring diagrams, and circuit troubleshooting.

• Loader and backhoe assemblies: Frame, boom, dipperstick, bucket, and cylinder service, with separate procedures and exploded views for the backhoe variants.

• System testing: Visual inspections, troubleshooting charts, pressure checks, hydraulic analyzer connections, circuit-leakage tests, and component-specific adjustment specifications.

This manual was written for experienced service technicians working with the required measuring instruments and workshop equipment.

Internal Engine Repair and Fuel-System Limits

Engine coverage extends to cylinder liners, connecting rods, camshaft, main bearings, oil pump, radiator, water pump, and thermostat. Illustrated inspection dimensions, wear limits, torque tables, and special-tool references accompany the repair sections.

The engine chapter identifies pneumatic removal or installation of connecting-rod and main-bearing cap screws as a potential cause of thread damage. The nozzle section warns that prying injectors from the cylinder head can distort and permanently damage them.

Injection equipment: Pump calibration data and installation/timing information are included. Detailed internal injection-pump and nozzle servicing refers to the separate SM-2045 manual, which is not included. Gasoline sections address carburetor adjustments, governor repair, distributor, coil, and spark plugs.

Clutches, Reverser, and Final Drives

Step-by-step procedures cover splitting the tractor for clutch access and dismantling the reverser’s forward clutch and reverse brake assemblies. Transmission work includes shaft inspection, bearing preload, and cone-point adjustment; differential service adds backlash adjustment and parking-brake linkage work.

The Collar Shift Transmission power-flow illustration connects individual gears with the diagnostic discussion. Serial-specific illustrations distinguish control linkages and the earlier high-range reverse lockout.

Closed-Center Hydraulics and Fault Isolation

Main pump repair distinguishes versions with and without a serial number plate. The Oil Flow Through Main Hydraulic Pump illustration explains the pump circuits, while steering, brake, and implement-valve sections provide component repair and adjustment information.

Analyzer testing: Test-port locations, temperature and speed conditions, and the Test Pattern Analysis Chart help distinguish pump faults from leakage elsewhere in the system before components are removed. Separate procedures address circuit leakage, cylinder leakage, accumulator pressure, and reverser clutch pressure.

Electrical Circuits and Working Equipment

The Electrical Schematic, Component Location drawing, and Component Wire Routing views connect circuit diagnosis with terminal identifiers and wire-color tables. Starting, charging, ignition, lighting, and instrument faults receive separate troubleshooting coverage.

Mechanical sections address front axle and steering linkage repairs, loader structural work, backhoe swing-frame and pivot components, cylinder packing, and the three-point hitch. Separate 9250 and 9250-A sections identify differences in control valves, cylinders, and backhoe construction.

For work involving raised attachments or stored hydraulic pressure, follow the complete OEM procedures. Repairs require qualified personnel equipped with the proper workshop tooling.

Examples of Valve-Adjustment and Bearing Data

Valve tappet clearance is specified with the engine either hot or cold: intake clearance is 0.014 in. for diesel and gasoline engines, while exhaust clearance is 0.018 in. for diesel and 0.022 in. for gasoline.

The basic-engine tables list main bearing bore I.D. at 3.3250–3.3260 in. This housing dimension is distinguished from the assembled bearing inside diameter and bearing-to-journal clearance.