Two engine variants, two different torque values, and one manual that keeps them straight. This Kubota RT Workshop Manual covers the RT and RT DI diesel engines behind the RT80, RT90, RT100, RT110, and RT120. Three pages of tightening torque tables handle both variants, with more torque figures called out through 50 pages of disassembly and reassembly steps. Six pages of diagrams map engine dimensions, component layouts, and performance graphs, while 8 pages of clearance specs cover every model in the range. A troubleshooting section runs through nine failure modes, from hard cold starts to abnormal oil consumption. Set the cylinder head mounting nut to 1100 ± 100 kg.-cm. on the RT or 1500 ± 100 kg.-cm. on the RT DI, and torque the flywheel nut to 3500 ± 500 kg.-cm. Bookmarked and searchable, it loads on a tablet so you reach any procedure before the first wrench turns.
What's Inside This Kubota RT, RT DI Manual
| System | Pages | Key Topics |
|---|---|---|
| Tightening Torque Table | 4 | Tightening Torques Table, Strength Of Bolt Indication, Indication Material Table |
| Tightening Torques Diesel Engine RT | 5 | Tightening Torques Diesel Engine, RT Table, Engine Component Torque Values, Comparision |
| Tightening Torques Diesel Engine RT DI | 6 | Tightening Torques Diesel Engine RT DI Table, Engine Component Torque Values, Comparision |
| RT Engine Specifications | 7-10 | Cylinder Head Specifications, Valve Specifications, Valve Spring Specifications, Rocker Arm Specifications, Camshaft Specifications, Liner Specifications |
| RT DI Engine Specifications | 11-14 | Cylinder Head Specifications, Valve Specifications, Valve Spring Specifications, Rocker Arm Specifications, Camshaft Specifications, Liner Specifications |
| RT Engine Radiator Net Specification | 15-16 | Engine Type And Cylinders, Bore And Stroke, Total Displacement, Max Power, Net Power, Max Torque, Fuel Consumption, Compression Ratio |
| RT Engine Performance Graph | 17-18 | RT80 Performance Graph, RT90 Performance Graph, RT100 Performance Graph, RT110 Performance Graph, RT120 Performance Graph |
| RT DI Engine Performance Graph | 19-20 | RT 100 DI Performance Graph, RT 110 DI Performance Graph, RT 120 DI Performance Graph, RT 140 DI Performance Graph |
| Dimensions | 21 | Engine Dimensions Diagram, Model Dimensions Table, Model Specifications |
| Features | 22 | Engine Components Diagram |
| Removing Engine | 23-45 | Changing Coolant (Water Drain), Draining Engine Oil (Oil Drain), Draining Fuel (Fuel Drain), Removing Fuel Tank Side Cover 1 And 2, Removing Fuel Tank Cover 3, Removing Engine Hook |
| Measurement | 46-77 | Checking Compression Pressure, Checking Cylinder Head Surface Flatness (Distortion Of Cylinder Head Surface), Checking Valve Seat Width, Checking Valve Recessing |
| Reassembling | 78-98 | Reassembling Liner, Reassembling Tappets, Reassembling Crankshaft, Reassembling Piston To Connecting Rod, Reassembling Piston Ring, Arranging Piston Ring Gap |
| After Reassembling | 99-107 | Filling Coolant, Filling Engine Oil, Filling Fuel, Closing Fuel Cock, Removing Injection Pipe And Fuel Line From Fuel Filter, Removing Fuel Pump, Removing Spring Lock And Cup Pin |
| Maintenance | 108 | Maintenance Schedule Table, Coolant Maintenance, Engine Oil Maintenance, Air Cleaner Maintenance, Solar Oil Filter Maintenance, Fan Belt Maintenance, Solar Oil Tank Maintenance |
| Troubleshooting | 109-113 | Engine Does Not Start, Engine Shakes Abnormal, Engine Power Down, Exhaust Gas Color Is Abnormal, Engine Oil Consumption Is Higher Than Normal, Engine Oil Is Clearer Than Normal |
Quick Reference Specifications
| Specification | Value | Page |
|---|---|---|
| All Models | ||
| General Bolt Torque (M6, Standard) | 80 - 95 kg.-cm. | p. 4 |
| General Bolt Torque (M10, Standard) | 400 - 460 kg.-cm. | p. 4 |
| Flywheel mounting nut torque | 3500 ± 500 kg.-cm. | p. 5 |
| Valve stem clearance (Allowable limit) | 0.1 mm. | p. 7 |
| Piston ring gap (Allowable limit) | 1.2 mm. | p. 8 |
| Oil pressure (Standard) | 2.5 kg/cm2 | p. 9 |
| Fan belt tension | 10 - 15 mm. | p. 10 |
| Radiator cap pressure (Standard) | 0.85 - 1.05 kg/cm2 | p. 10 |
| RT | ||
| Cylinder head mounting nut torque | 1100 ± 100 kg.-cm. | p. 5 |
| RT DI | ||
| Cylinder head mounting nut torque | 1500 ± 100 kg.-cm. | p. 6 |
| RT80-RT90 | ||
| Coolant capacity | 1.6 L. | p. 15 |
| RT120-RT140 | ||
| Coolant capacity | 2.2 L. | p. 16 |
Kubota RT, RT DI Common Problems This Manual Covers
Kubota RT diesel engine cranks but won't fire in cold weather, starter turns slowly p. 109
Start at the troubleshooting chart on page 109. Open the fuel cock and bleed trapped air from the fuel line, then inspect the injection nozzle for wear or clogging and test compression. Confirm oil pressure reaches at least 2.5 kg/cm2 (page 9) before you keep cranking.
Manual Section: TroubleshootingEngine temperature climbs to red zone at operating load, coolant overflow or steam from cap p. 109
Test the radiator cap first: it should hold 0.85 to 1.05 kg/cm2 per page 10, since a weak cap releases coolant too early. Tension the fan belt to 10 to 15 mm deflection (page 10), clean clogged radiator fins, and inspect the head gasket for combustion gases leaking into the coolant.
Manual Section: TroubleshootingExhaust blowing black or dark grey smoke at full throttle, power feels flat p. 109
Clean the air filter every 100 hours per the maintenance schedule on page 108; a clogged element starves combustion right away. Check injection timing and inspect the nozzle for a worn tip or sticking plunger spring, then measure cylinder wall clearance in the Measurement section on page 74.
Manual Section: TroubleshootingOil pressure warning light stays on at idle, engine knocking or ticking sounds p. 109
Stop the engine immediately, then check the oil level and refill if low. Standard oil pressure should reach 2.5 kg/cm2 (page 9); if it stays low after a refill, inspect the oil pump rotor for wear and check the pressure control spring. Excessive bearing clearance also bleeds pressure down, so check clearances in the Measurement section on pages 71-72.
Manual Section: TroubleshootingEngine runs with rough uneven idle, vibration increases under load throughout all RPM ranges p. 109
Adjust the intake and exhaust valves, which fall due every 300 hours per the maintenance schedule on page 108; valve stem clearance must stay within the 0.1 mm allowable limit (page 7). Check gear mark alignment for correct injection timing, inspect the governor spring for defects, and test each nozzle individually to find a dead cylinder.
Manual Section: TroubleshootingEngine loses power under load, rpm drops and won't recover at full throttle p. 109
Replace the fuel filter if it is overdue, since a blocked element starves the injection pump. Inspect the nozzle pin for wear and measure compression in the Measurement section on page 46; piston ring gap must stay under the 1.2 mm allowable limit (page 8). Worn liners or rings drop compression and kill power before anything else.
Manual Section: TroubleshootingFrequently Asked Questions
What are the recommended service intervals?
Service intervals run on a daily-plus-hourly schedule. Coolant gets a daily check. Engine oil is checked daily and replaced every 100 hours (1 month), as is the air cleaner, which is cleaned on the same 100-hour interval. Fan belt tension also gets adjusted every 100 hours (1 month).
What fluids and capacities does this machine require?
Capacities depend on the model. RT80 to RT90 units hold 1.6 L of coolant, 2.4 L of engine oil, and 10 L of fuel. RT100 to RT140 units step up to 2.2 L of coolant, 2.8 L of engine oil, and 11 L of fuel.
How to troubleshoot engine won't start?
Two cases split the diagnosis: the starter won't run, or it runs but the engine won't fire. A dead starter points to a seized crankshaft and camshaft, seized piston and ring, or seized bearing, each needing repair. When the starter does turn, look at insufficient fuel, a leaking fuel line, or a malfunctioning injection pump, which call for a fix or replacement.
What torque specifications are listed?
Torque figures run from general fasteners to named engine parts. A standard M6 bolt takes 80 - 95 kg.-cm., while a special M20 climbs to 5,000 - 5,800 kg.-cm. Among engine components, the RT exhaust pipe mounting bolt and nut call for 260 ± 20 kg.-cm., and the flywheel mounting nut for 3500 ± 500 kg.-cm.
What are the common electrical problems?
The electrical entries center on light malfunctions. Causes range from a broken bulb, disconnected wiring, and loose or dirty connectors to a loose or dirty ground line, a torn fan coil, or a blown fuse. Fixes mean either replacing the failed part or repairing the connection.
What format is this Kubota RT, RT DI manual in?
Delivered as an instant PDF download. The full 113-page searchable Workshop Manual lands in your account right after payment, ready to open on a laptop, tablet, or phone in the shop.
Are there any print restrictions on this Kubota RT, RT DI manual?
Yes. The PDF carries no DRM restrictions, so you can print any page or section your shop needs. It works with any standard printer.
Document Quality
This document is a scanned PDF, meaning the text is generally clear and readable but not as crisp as a native digital file. An OCR layer is present, so you can search and copy text throughout the document. Diagrams, illustrations, and photos are raster images, which may show some pixelation when zoomed, but their labels are mostly legible. The pages are clean with no significant scan artifacts, stains, or skewed content. There are no notable blank or filler pages.
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