Part of the Yanmar Parts Manuals.
Ten minutes after checkout you can have the exploded view of the B25V-1 idler assembly open on your phone, matching the seal and collar on your bench to a numbered callout instead of squinting at a worn casting. That is what this 13-page Yanmar parts catalog (publication 000Y00S3680) is for: the B25V-1 crawler backhoe, built around the 3TNE78A - B1A engine, reference B6040.
It is organized into five sections: Roller & Adjust, Crawler, Hyd. Oil Pump & Joint, and two Control Valve chapters that break the valve bank down into bucket, boom, arm, swing, blade, drive, turning and P.T.O. sections, with the relief valve settings printed alongside.
Guessing at part numbers on a machine this age is expensive: a mis-ordered coupling, a week of downtime, a second teardown to fit the right seal. This catalog gets you the correct number the first time.
What's Inside This Yanmar B25V-1, 3TNE78A - B1A, B6040 Parts Manual
| System | Pages | Key Topics |
|---|---|---|
| Roller & Adjust | 3-4 | Sprocket, Idler Assembly, Mechanism, Track Roller Assembly, Carrier Roller Assembly |
| Crawler | 5-6 | Rubber Component |
| Hyd. Oil Pump & Joint | 7-8 | Hydraulic Oil Pump Assembly, Coupling, Valve Block Assembly, Gear Pump |
| Control Valve (1/2) | 9-10 | T1-Port Components, Bucket Section, Boom Section, Drive Section, P1, P2-Port Components |
| Control Valve (2/2) | 11-13 | Arm Section, P.T.O. Section, T2-Port Components, Turning Section, Blade Section, Control Section, Swing Section |
Quick Reference Specifications
| Specification | Value | Page |
|---|---|---|
| Relief Valve Setting (Boom/Bucket) | 210/20 | p. 8 |
| Relief Valve Setting (Swing) | 185/31 | p. 8 |
| Relief Valve Setting (Arm) | 220/20 | p. 10 |
| Idler Size | 289 | p. 2 |
| Seal Dimensions | 45x85x8.5x19 | p. 2 |
| Circlip Size | 30 | p. 2 |
| O-Ring 1B Size | P-14.0 | p. 2 |
| Packing G Size | 35.0 | p. 2 |
| Bearing Type | #6205 | p. 2 |
Yanmar B25V-1, 3TNE78A - B1A, B6040 Common Problems This Manual Covers
Rubber track cracked or thrown
Age-hardened rubber tracks on the B25V-1 crack at the lugs and eventually walk off the undercarriage. The Crawler section gives the assembly diagram and the rubber component part number so you order the correct replacement track, not a near-fit.
Manual Section: Crawler p. 5Track tension will not hold
If the track goes slack again days after adjusting, the adjusting mechanism or idler assembly is usually worn or leaking. The Roller & Adjust section breaks down the sprocket, idler, adjusting mechanism and both roller assemblies part by part.
Manual Section: Roller & Adjust p. 3Slow, weak hydraulics
Sluggish boom and arm response on older Yanmar machines often traces back to a tired pump or contaminated oil. The Hyd. Oil Pump & Joint section identifies the hydraulic oil pump assembly and gear pump components so you can rebuild or replace with the right parts.
Manual Section: Hyd. Oil Pump & Joint p. 7Noisy or sticking joystick function
Owners report loud hydraulic noise when working a joystick, which typically points at a valve section rather than the pump. Control Valve (1/2) diagrams the bucket, boom and drive sections along with the T1, P1 and P2 port components.
Manual Section: Control Valve (1/2) p. 9Arm drift or swing creep
An arm that settles under load or a house that creeps off center usually means worn spools or seals in those valve sections. Control Valve (2/2) covers the arm, swing, turning, blade, control and P.T.O. sections down to individual components.
Manual Section: Control Valve (2/2) p. 11Leaks at pump and coupling
Seeping fittings and a worn drive coupling between engine and pump are common on machines with this many hours. The Hyd. Oil Pump & Joint section lists the coupling and valve block assembly parts, so you replace exactly what is leaking instead of guessing at seals.
Manual Section: Hyd. Oil Pump & Joint p. 7Frequently Asked Questions
Which machine does this parts catalog cover?
The Yanmar B25V-1 crawler backhoe with the 3TNE78A - B1A engine, reference B6040. It is the factory parts catalog, publication number 000Y00S3680, in English.
Does it include hydraulic relief valve settings?
Yes. The Hyd. Oil Pump & Joint section lists the boom and bucket relief setting as 210/20 and swing as 185/31 on page 8, with the arm setting of 220/20 given in the control valve pages. p. 7
Can I identify undercarriage parts with it?
Yes. The Roller & Adjust section breaks down the sprocket, idler assembly, adjusting mechanism, track roller and carrier roller assemblies, followed by a crawler parts list, so you can pull exact part numbers for the whole undercarriage. p. 3
Does it include engine repair procedures?
No. This is a parts catalog, not a service manual, and its sections cover the undercarriage, hydraulic pump and joint, and both control valve groups. Use it to identify and order parts, not for step-by-step repair instructions.
How will I receive this Parts Catalog?
Instant PDF download. You get the full 13-page searchable Parts Catalog immediately after payment. Open it on your laptop, tablet, or phone right in the shop.
Can I print specific sections of this Parts Catalog?
Yes. The PDF has no DRM restrictions, so print any page or section you need for your shop. Works with any standard printer.
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