Part of the Kubota Repair Manuals.
This Kubota Service Manual covers the Z231BR-AU, Z231KH-AU, Z251BR-AU, and Z251KH-AU zero-turn mowers sold in Australia, running the GH731V-1, GH736V, GH733V-1, and GH750V engines. It is a 188 page PDF you download and keep for the life of the machine.After the safety and general sections, with product identification and full tightening torque tables, it moves through maintenance and service intervals, then the engine, transaxle, front axle, lift system, electrical system, and mower deck. Each mechanical section separates how the part works from how to service it.Use it to set the electric PTO clutch clearance, service the hydrostatic transaxle, trace electrical faults, replace blades to the correct torque, and keep the mower on its factory service schedule.
What's Inside This Kubota Z231–Z251 Series Manual
| System | Pages | Key Topics |
|---|---|---|
| Supplementary Information | 3 | Model Name and Related Manuals, Model Name, Record of Revisions, Main Revised Point and Corrective Measure |
| Record of Revisions | 4-10 | Main Revised Point and Corrective Measure, Last Digit of the Code No, Month of Revision, Reference Page |
| Safety | 11-21 | - |
| General | 22-44 | Tightening Torques (Stud Bolts, Hydraulic Fittings, Metric Screws, Bolts and Nuts, American Standard Screws, Bolts and Nuts with Unc or Unf Threads, Plugs), Product Identification |
| Maintenance | 45-75 | Lubricants and Fuel, Service Intervals |
| Engine | 76-94 | Z231KH-Au (GH736V), Z251KH-Au (GH750V) Kohler Engine, Z231BR-Au (GH731V-1), Fuel System |
| Transaxle | 95-127 | Hydraulic Circuit of Transaxle, Transaxle External Components, Fan Function, Pulley Function |
| Front Axle | 128-134 | Troubleshooting, Tightening Torques, Separating Front Wheel and Wheel Bracket, Removing Front Wheel, Removing Wheel Bracket |
| Lift System | 135-143 | Troubleshooting, Tightening Torques, Checking Link Stopper, Adjusting Link Stopper, Removing Link Shafts, Removing Mower |
| Electrical System | 144-166 | Wiring Diagram, Starting System, Electrical Circuit of Starting System, Safety Switch, Property of Safety Switch |
| Mower | 167-188 | Power Transmission Flow for Mower, Troubleshooting, Servicing Specifications, Tightening Torques, Leveling Mower Deck, Adjusting Anti-Scalp Rollers |
Quick Reference Specifications
| Specification | Value | Page |
|---|---|---|
| All Models | ||
| Engine crankcase oil capacity (with filter) | 1.8 L | p. 46 |
| Transmission case fluid capacity (with filter, hose and tank) | 4.8 L | p. 46 |
| Flange bolt (Electric clutch) torque | 62.8 N·m | p. 86 |
| Hub retaining nut torque | 109 N·m | p. 105 |
| Blade bolt torque | 103 N·m | p. 175 |
| Front tire inflation pressure | 170 kPa (25 psi) | p. 55 |
| Rear tire inflation pressure | 110 kPa (16 psi) | p. 55 |
| Electric PTO clutch clearance | 0.35 mm | p. 156 |
| Z231BR-AU | ||
| Max. engine power (Gross) | 16.4 kw (22.0 HP) | p. 31 |
| Z231KH-AU | ||
| Max. engine power (Gross) | 15.7 kw (21.0 HP) | p. 31 |
Kubota Z231–Z251 Series Common Problems This Manual Covers
Uneven or poor quality cut
An uneven cut usually comes back to blade condition, deck level, or spindle wear. The mower section covers the deck mechanism and servicing.
Manual Section: Mower p. 167Weak drive or one side pulling
A zero-turn that drifts or loses drive on one side is worked through the hydrostatic transaxle. This section separates how it works from how to service it.
Manual Section: Transaxle p. 95Electric PTO clutch will not engage
The blades are driven by an electric PTO clutch that must sit within a set clearance. The electrical system section covers the clutch and its servicing.
Manual Section: Electrical System p. 144Engine runs poorly or will not start
Starting and running faults are diagnosed in the engine section, which covers both the mechanism and servicing for the fitted engine.
Manual Section: Engine p. 76Deck will not raise or hold
A deck that will not lift or drops is traced through the lift system section covering its mechanism and servicing.
Manual Section: Lift System p. 135Front caster wander or wear
Loose or worn front casters affect stability and cut. The front axle section covers the mechanism and servicing.
Manual Section: Front Axle p. 128Missed or overdue service
Skipped service leads to most early failures. The maintenance section lists lubricants, fuel, and the service intervals to keep to.
Manual Section: Maintenance p. 45Frequently Asked Questions
Which mowers and engines does this cover?
It covers the Australian market Kubota Z231BR-AU, Z231KH-AU, Z251BR-AU, and Z251KH-AU zero-turn mowers, running the GH731V-1, GH736V, GH733V-1, and GH750V engines.
Does it include tightening torque specifications?
Yes. The general section gives tightening torques for general use screws, stud bolts, hydraulic fittings, metric and American standard threads, and plugs. p. 22
Is the hydrostatic transaxle service covered?
Yes. The transaxle section covers both the mechanism and the servicing procedures for these zero-turn units, including checks and adjustments. p. 95
Does it cover the electrical system and PTO clutch?
Yes. The electrical system section covers the mechanism and servicing, including the electric PTO clutch and its clearance. p. 144
How quickly can I access this Kubota Z231–Z251 Series manual after buying?
A 188-page Service Manual in searchable PDF, ready the moment your checkout clears. Open it on a computer, tablet, or phone with no shipping wait.
Am I able to print pages from this Kubota Z231–Z251 Series manual?
Yes. Print as many copies as you like, with no restrictions. Plenty of mechanics print just the section they need and carry it to the shop floor.
Does this Kubota Z231–Z251 Series Service Manual cover the hydraulic system?
Yes. The manual includes full hydraulic diagrams covering circuits, valve locations, and component specs for the Kubota Z231-Z251 Series.
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