All 248 pages of this Yanmar YB451, YB501 Crawler Backhoe Parts Catalog (OEM #Y00K2094) map factory part numbers for every 1985–1991 YB451(-2) and YB501(-2) variant, covering P, C, and UZ chassis configurations. Inside you get exploded-view diagrams and numbered parts tables across the entire machine: engine mount, fuel system, hydraulic oil pump and piping schematics, control valves, boom and arm cylinders, track frame, swivel joint, turning motor, and full cabin and canopy assemblies. Wiring diagrams detail the complete electrical layout, wire color codes, and harness routing for both canopy and cabin specs. Machine travel is rated at 3.6 km/h high range and 1.9 km/h low range, with ground pressure and model dimensions included in the specifications section. No more ordering the wrong-variant part and waiting a week to find out. Bookmarked by section and searchable by keyword, pull it up on your phone at the parts counter and get the right number on the first call.
What's Inside This Yanmar YB451 / YB501 Series Parts Manual
| System | Pages | Key Topics |
|---|---|---|
| Preface | 1-2 | Parts Catalog Scope, Model Applicability, Catalog Revision History, Paint Color Codes |
| Specifications | 3 | Model Dimensions, Operating Capacities, Digging Performance, Travel Characteristics, Ground Pressure, Machine Mass |
| Parts Name | 4-5 | Engine Mount & Radiator, Hyd. Oil Tank, Swing Cylinder, Arm Cylinder, Boom Cylinder, Blade |
| Wiring Diagram | 6-10 | Wire Color Codes, Starter Circuit, Wiper Circuit, Heater Circuit, Electrical Component Connections |
| Label (Canopy Spec.) | 11-13 | Specification Labels, Grease Point Labels, Stripe Identification, Operation Warning Labels, Fuel and Fluid Labels, Model and Brand Labels |
| Label (Cabin Spec.) Fig 2 | 14-16 | Specification Labels, Model Identification, Stripe Labels, Operation and Safety Warnings, Fluid Type Labels, Maintenance Instruction Labels |
| Label (Cabin Spec.) Fig 3 | 17-19 | Model Identification Labels, Stripe and Specification Labels, Fluid and Coolant Labels, Safety and Caution Labels, Air Cleaner Labels, Seal Labels |
| Label (Cabin Spec.) Fig 4 | 20-22 | Model and Specification Labels, Fluid and Grease Labels, Safety and Warning Labels, Component Identification Labels, Air Cleaner Labels, Seal and Stripe Labels |
| Tool | 23-24 | Assy, Pin, Cotter, Driver, Screw, Wrench, Bar Wrench |
| Rear View Mirror | 25-26 | STAY(L), Back Mirror, STAY(R), Mirror, Bolt |
| Silencer | 27-28 | Support, Gasket, Bolt W/WASHER, Hose, Air Cleaner |
| Accelerator | 29-30 | Lever Assy, Throttle, Cable, Spring, Side Clutch, Knob, Pivot |
| Engine Mount & Radiator | 31-32 | Support, Engine, Bracket, Absorber, Shock, Mount, Radiator, Hose |
| Fuel Tank & Fuel Line | 33-38 | Fuel Tank, Fuel Line, Cock, Cap, Fuel Strainer, Hose, Fuel Pump, Gasket |
| Battery | 39-40 | Cord, Terminal, Sensor, Retainer, Mount |
| Electric Part (Canopy Spec.) | 41-43 | Harness, Wire, Fuse Box, Switch, Meter, Relay, Lamp, Bulb |
| Electric Part (Cabin Spec.) Fig 15 | 44-46 | Harness, Lead Wire, Fuse Box, Lamp Assy, Meter, Switch Assy |
| Electric Part (Cabin Spec.) Fig 16 | 47-49 | Heater Assy, Valve, Miniature, Switch, Heater, Defroster Assy |
| Heater & Defroster | 50-51 | Radio Assy, Lead Wire, Panel, Radio, Screw, Bolt |
Quick Reference Specifications
| Specification | Value | Page |
|---|---|---|
| Travel speed | 3.6 - 1.9 km/h | p. 3 |
Yanmar YB451 / YB501 Series Common Problems This Manual Covers
Yanmar YB451 weak travel power, one track pulling harder than the other, or poor tracking performance p. 187
Check the Travel Motor exploded view on page 187. Locate the required seal set and O-rings for your specific motor assembly. Verify your machine maintains the factory 3.6 - 1.9 km/h travel speed specification. Order the exact replacement parts listed for your serial number.
Manual Section: Travel MotorAccelerator pedal feels loose, linkage binding, or third valve stopper failing to hold position p. 243
Review the Valve Stopper diagram on page 243. Inspect the accelerator pivot and conical washer for wear. Replace the M10 cap nut and 10 mm washer if threads are stripped. Match the exact part numbers to ensure the 3rd valve stopper functions properly.
Manual Section: Valve Stopper (Optional)Hydraulic fluid leaking from the power take-off selector valve or pressure dropping under load p. 239
Examine the P.T.O. Valve Piping on page 239. Locate the selector valve body and sub-plate in the parts diagram. Inspect the PT1/16 plug and rubber O-ring for damage. Order the correct replacement spool and seals to prevent further fluid loss.
Manual Section: P.T.O. Valve Piping (U,Uz) (Optional)Worn bucket side cutters, missing teeth, or excessive play in the attachment pins p. 191
Check the Bucket400 (Attachment) exploded view on page 191. Identify the correct replacement side cutter and teeth assembly for your 400 mm bucket setup. Order the matching pin assembly and specific shims to eliminate excess movement and restore digging performance.
Manual Section: Bucket400 (Attachment)Frequently Asked Questions
What are the replacement specifications for track idler?
The replacement specifications for the track idler include the "IDLER ASSY" (part number 772124-37110 or 172124-37200, quantity 2), "SHAFT, IDLER" (part number 172124-37130, quantity 2), and "SEAL 66 86 28" (part number 933112-00500, quantity 4). These details are found in the "Track Frame & Idler" section.
What are the replacement specifications for track rollers?
The replacement specifications for track rollers include "ROLLER ASSY, TRUCK" (part number 772124-37300 or 172124-37400, quantity 8), "BUSH, ROLLER" (part number 172124-37310, quantity 16), "SHAFT, ROLLER" (part number 172124-37320, quantity 8), and "SEAL 64 78 25" (part number 933112-00400, quantity 16). These details are found in the "Track Roller & Carrier Roller" section.
How do you fix yanmar YB451 weak travel power, one track pulling harder than the other, or poor tracking performance?
Check the Travel Motor exploded view on page 187. Locate the required seal set and O-rings for your specific motor assembly. Verify your machine maintains the factory 3.6 - 1.9 km/h travel speed specification. Order the exact replacement parts listed for your serial number.
How do you fix accelerator pedal feels loose, linkage binding, or third valve stopper failing to hold position?
Review the Valve Stopper diagram on page 243. Inspect the accelerator pivot and conical washer for wear. Replace the M10 cap nut and 10 mm washer if threads are stripped. Match the exact part numbers to ensure the 3rd valve stopper functions properly.
What format is this manual in?
Instant PDF download. You get the full 248-page searchable Parts Catalog immediately after payment. Open it on your laptop, tablet, or phone right in the shop.
Can I print this manual?
Yes — DRM-free PDF. Print whatever sections you need to take out to the shop. Standard letter or A4 paper works.
Are there wiring harness diagrams in this Yanmar YB451 & variants manual?
A wiring diagram for the Yanmar YB451 & variants electrical system is included.
Document Quality
This is a scanned PDF document with an OCR layer, allowing you to search and copy text throughout. The text quality is generally crisp and readable, despite the slight pixelation typical of scanned materials. All diagrams and illustrations are raster images; while mostly clear, some fine lines and very small labels may appear slightly pixelated when highly magnified, but remain readable at normal viewing levels. The pages are consistently clean, free of significant marks or skewing, and there are no notable blank or filler pages.
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