Kubota built this manual (OEM #9Y011-02185) for one job: factory-level service on the Z602-E and D902-E compact diesels. Fifty pages walk through hands-on procedures, from engine body teardown and reassembly to the lubricating system, cooling system overhaul, fuel system adjustment, and the full electrical side including starter, alternator, glow plug, and engine stop solenoid. Around those procedures sit a troubleshooting section, timed maintenance checklists from 50-hour to 3000-hour intervals, exploded views of every major assembly, system diagrams, and performance curves for both variants. Need the injection pipe retaining nut torque? It's 24.5 to 34.3 N-m. Filling a D902-E? Capacity is 3.7 L. The figures are printed, not guessed. Every section is bookmarked and the text is searchable, so any spec is a keyword away.
What's Inside This Kubota Z602-E, D902-E Manual
| System | Pages | Key Topics |
|---|---|---|
| Record of Revisions | 3 | Added The Information Of Metal Cylinder Head Gasket, Added The Information About Model Name And New Engine Serial Number |
| Safety Instructions | 4-7 | Safety First, Danger, Warning, Caution, Important, Note, Before Servicing And Repairing, Safety Starting |
| Specifications | 8 | Model, Type, Number Of Cylinders, Bore - Stroke, Total Displacement, SAE Net Continuous, SAE Net Intermittent, Maximum Bare Speed |
| Performance Curves | 9-10 | Z602-E Performance, Performance Curve Legend, D902-E Performance |
| Dimensions | 11-13 | Z602-E Dimensions, Unit Of Measurement, D902-E Dimensions |
| Mechanism | 14-17 | Engine Body (Half-Floating Head Cover), Piston, Oil Pan, Cooling System (Cooling Fin) |
| Servicing | 18-108 | General, Engine Body Servicing, Lubricating System, Cooling System Servicing, Fuel System, Electrical System |
Quick Reference Specifications
| Specification | Value | Page |
|---|---|---|
| All Models | ||
| Cylinder head cover screw tightening torque | 6.86 to 11.3 N-m (0.7 to 1.15 kgf-m, 5.1 to 8.3 ft-lbs) | p. 25 |
| Injection pipe retaining nut tightening torque | 19.6 to 24.5 N-m (2.0 to 2.5 kgf-m, 14.5 to 18.1 ft-lbs) | p. 25 |
| Cylinder Head Cover Torque | 6.86 to 11.3 N-m | p. 25 |
| Injection Pipe Retaining Nuts Torque | 24.5 to 34.3 N-m | p. 25 |
| Nozzle Holder Assembly Torque | 49.0 to 68.6 N-m | p. 25 |
| Cylinder Head Screw Torque | 37.3 to 42.2 N-m | p. 25 |
| Valve Clearance (Cold) | 0.145 to 0.185 mm | p. 30 |
| Compression Pressure (Factory Spec) | 3.53 to 4.02 MPa | p. 30 |
| Engine Oil Pressure (At Rated Speed, Allowable Limit) | 147 kPa | p. 34 |
| Fan Belt Tension | 7.0 to 9.0 mm / 98 N | p. 34 |
| Z602-E | ||
| Lubricating Oil Capacity | 2.5 L | p. 8 |
| D902-E | ||
| Lubricating Oil Capacity | 3.7 L | p. 8 |
Kubota Z602-E, D902-E Common Problems This Manual Covers
Kubota Z602-E diesel cranks but won't fire, no fuel reaching the injection nozzles
Confirm the fuel shutoff valve is open and the tank holds fuel. Bleed air from the system by loosening the injection pipe retaining nuts, then re-torque to 24.5 to 34.3 N-m. Inspect the fuel filter and lines for clogs. In cold weather, make sure oil viscosity suits the ambient temperature. Injection timing faults round out the full cause list.
Manual Section: Engine Does Not StartEngine RPM surges and hunts at idle, unstable governor response under varying load
Clean or replace the air cleaner element (service every 100 hrs, replace at 500 hrs, page 36). Check the injection pipe retaining nuts and torque them to 24.5 to 34.3 N-m if loose. Inspect the injection nozzle for clogging or a bad spray angle. Test the governor linkage for sticking or binding, which upsets fuel metering at idle.
Manual Section: Engine Revolution Is Not SmoothOil pressure drops at operating temperature and rated speed, oil warning light illuminated
Verify the oil level and top off if low; your model's capacity is on page 8. Inspect the oil strainer and filter cartridge for clogs, and replace the cartridge every 200 hrs. At rated speed the allowable oil pressure is 147 kPa. If pressure stays low after service, check the relief valve for trapped dirt or a weak spring.
Manual Section: Low Oil PressureEngine temperature climbs to red zone, coolant boiling over through overflow hose
Top off the coolant if the level is low. Inspect the fan belt for cracks or poor tension; correct deflection is 7.0 to 9.0 mm under a 98 N load. Clear any debris packed into the radiator fins. Confirm the thermostat opens at 69.5 to 72.5 degrees C, since one stuck closed is a frequent overheating cause. Swap the coolant every 2 years.
Manual Section: Engine OverheatedEngine blows white or blue smoke at startup, oil smell in exhaust
Measure compression pressure; the factory spec is 3.53 to 4.02 MPa (page 30). Worn piston rings drive most blue smoke, so inspect the ring gaps and make sure no two openings line up. If white smoke lingers after warmup, look for head gasket failure and coolant loss. Check injection timing and the nozzle spray pattern.
Manual Section: Either White or Blue Exhaust Gas Is ObservedFrequently Asked Questions
What are the recommended service intervals?
The maintenance check list runs through a range of service intervals. Fuel hose and clamp band replacement is on page S-21, engine oil changes on S-22, and the oil filter cartridge on S-24. Listed intervals span every 50, 100, 200, 400, 500, 800, 1500, and 3000 hours, plus every 1 or 2 years.
What fluids and capacities does this machine require?
The Z602-E holds 2.5 L (2.64 U.S.gals) of lubricating oil; the D902-E takes 3.7 L (3.91 U.S.gals). API Class CF oil is recommended, and CF-4 or CG-4 oils work too. Above 25 °C, run SAE 30 or SAE 10W-30/10W-40. Keep the cooling system's anti-freeze mixing ratio under 50%.
How to troubleshoot engine won't start?
When the engine won't start, the usual culprits are no fuel (replenish, S-19), air in the fuel system (bleed, S-21), or a clogged fuel filter (change, S-22). It can also be off injection timing (adjust, S-75), a discharged battery (charge, S-81), or a faulty starter (repair or replace, S-81). For compression leaks, replace the head gasket and tighten the cylinder head screws (S-35, S-45).
What torque specifications are listed?
Torque figures cover the whole engine. The cylinder head cover screw runs 6.86 to 11.3 N·m (5.1 to 8.3 ft·lbs) and the injection pipe retaining nuts 24.5 to 34.3 N·m (18.1 to 25.3 ft·lbs). The nozzle holder assembly takes 49.0 to 68.6 N·m (36.2 to 50.6 ft·lbs), and the connecting rod screws 26.5 to 30.4 N·m (19.5 to 22.4 ft·lbs). General-use M6 screws sit at 7.9 to 9.3 N·m (5.8 to 6.9 ft·lbs).
What are the common electrical problems?
On the electrical side, a discharged battery just needs charging (S-81), and a failing starter calls for repair or replacement (S-81). Check glow plug continuity; resistance is roughly 0.9 Ω. Stator resistance should read under 1.0 Ω, and the slip ring O.D. has an allowable limit of 14.0 mm.
What format is this Kubota Z602-E, D902-E manual in?
Instant PDF download. The complete 108-page searchable Workshop Manual is available the moment payment clears, ready to open on a laptop, tablet, or phone in the shop.
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Document Quality
This is a native digital PDF document, allowing you to search and copy all text. The text quality is consistently crisp and clear throughout, ensuring easy readability. Diagrams and illustrations are a mix of sharp vector-like drawings and high-quality photos, with all labels being perfectly readable. The pages are clean, free from scan artifacts, stains, or skewed content. You will find a few filler pages that only contain chapter titles.
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