Kubota Z500-B - Z600B, ZH600-B, D650-B, D750-B Engine 1980–1999 Technical Manual (P/N WSM 60201-0)

This factory workshop manual covers Kubota 70 mm-stroke, vertical, water-cooled four-cycle diesel engines in the Z500-B, Z600-B, ZH600-B, D650-B, D750-B, D850-B, DH850-B, D950-B, V1100-B, VH1100-B, and V1200-B families. The scan is supplied as a 92-page PDF set: Part 1 contains 33 pages of specifications, performance curves, dimensions, and mechanism material; Part 2 contains 59 pages of disassembly and servicing information. Written for servicing personnel, it assumes prior diesel-engine repair experience plus access to precision measuring and injection-test equipment. The technical repair text is in English; front matter and selected captions also appear in French and German.

• Model and serial coverage: Identifies the two-, three-, and four-cylinder configurations and separates idle-gear shaft and bushing specifications at engine serial 407507, at 393782 for the D950-B, and again at 599860.
• Engine-body repair: Covers compression and top-clearance checks, cylinder-head and valve service, timing-gear and camshaft work, piston and connecting-rod removal, crankshaft and bearing inspection, and dry-liner replacement.
• Fuel-system diagnosis: Details the Bosch K-type mini injection pump, throttle-type nozzles, lift pump, filter, and centrifugal-ball all-speed governor, with injection-timing adjustment, pump-element and delivery-valve leakage tests, nozzle spray checks, and nozzle-pressure adjustment.
• Lubrication and cooling service: Provides oil-flow and cooling-circuit references, trochoid oil-pump inspection, oil-pressure testing, thermostat and radiator checks, and water-pump disassembly.
• Electrical testing: Includes alternator no-load output, regulator terminal checks, starter motor and magnet-switch tests, commutator and brush inspection, and glow-plug resistance testing.
• Shop data and tools: Supplies troubleshooting charts, torque tables, maintenance intervals, factory specifications, allowable wear limits, clearance data, and drawings for service tools used during major repair work.

Overhaul and Inspection Depth

The engine-body section goes beyond routine maintenance. It documents cylinder-head flatness and crack inspection, valve recession and seat correction, valve-guide replacement, camshaft alignment, timing-gear backlash, connecting-rod alignment, crankpin and main-bearing oil-clearance checks, crankshaft-sleeve replacement, and dry-cylinder-liner pulling, pressing, boring, and honing. Undersize and oversize bearing information is provided where standard bearings can no longer be used.

Fuel-system coverage follows the complete delivery path from the tank and filter through the lift pump, injection pump, delivery valve, lines, and nozzles. Governor drawings explain starting, idling, high-speed overload response, load increase, and engine-stop positions. Injection-pump internal service is deliberately limited: the manual states that the pump should not normally be disassembled and that replacement pump elements require fuel-delivery adjustment on a specified test bench.

Diagrams, Special Tools, and Specifications

Reference drawings include the engine-oil flow circuit, cooling-system layout, fuel-system flow diagram, all-speed governor operating views, alternator/regulator charging schematic, and labeled injection-pump and nozzle-holder assemblies. The special-tool section identifies factory tools and shop-made tool drawings, including Socket Wrench 29 07916-31841, Dry Liner Changer-II 07916-33061, Valve Seat Cutter Set 07909-33102, and Oil Pressure Tester 07916-32031.

Specifications are organized by assembly rather than scattered through generic notes. The tables cover tightening torque, compression and top clearance, valve and camshaft limits, timing-gear backlash, piston and ring wear, connecting-rod alignment, crankshaft and bearing clearances, cylinder-liner wear, oil pressure, thermostat and radiator testing, injection-pump and nozzle testing, starter wear limits, alternator output, and glow-plug checks.

Important Service Notes and Scope

The manual warns that main-bearing cases are not interchangeable and that the thrust-bearing oil groove must face outward; reversing these parts can compromise lubrication and damage the crankshaft bearings. It also calls for pistons to remain matched to their original cylinders and for a ring compressor during installation, since the chrome-plated ring surface can be scratched and the liner damaged.

Keep clear of the injection spray during nozzle testing, disconnect the battery ground before electrical service, and allow the cooling system to cool before opening the radiator cap. This is an engine workshop manual, not a tractor or equipment service manual: it does not cover transmissions, axles, chassis hydraulics, or machine wiring. The radiator, air cleaner, and muffler are discussed, but the manual notes that they are not included with the basic engine.