Description

Yanmar B2U-1, 3TNE74-N3AY, 3TNE74-EN3AY 2001 Parts Catalog

You ever order a part for a Yanmar crawler back-hoe, get the box, and find the bolt holes are half a millimeter off? That happens when you rely on a third-party parts list or a grainy PDF from some forum. This catalog is not that. It’s the actual 1st revised edition from Yanmar, published November 2001, covering the B2U-1 vehicle and the two engine variants: 3TNE74-N3AY and 3TNE74-EN3AY. Two hundred eighty pages of factory part numbers, paint color codes, and wiring diagrams – printed from the original Yanmar file. If you need to find the correct hydraulic hose, the right paint for the canopy, or the fuse layout, this is where you start.

Preface: What This Catalog Is (and Isn’t)

Page 1 spells it out: “This parts catalog is not a technical data manual setting forth as servicing procedures.” That means you don’t go to this book to learn how to rebuild the engine. You go here to find the exact part number for the piston ring, the spray can of Yanmar Ocean Green, or the wire color for the stop lamp circuit. The catalog uses simplified illustrations – they’re exploded views, not repair steps. If you try to use this as a service manual, you’re going to get lost. Get the service manual for that. But for parts ordering, this is the only source you should trust. The preface also explicitly warns against using cheap aftermarket parts: “Be careful not to use the simple parts available in the market, otherwise their use in repairing causes such as an early breakage.” That’s straight from Yanmar. I’ve seen it happen – a generic seal fails because the durometer is wrong. Factory spec matters.

Vehicle Painted Color and Paint Part Numbers

Pages 2 and 3 give you the full paint scheme for the B2U-1. Five distinct colors: Yanmar Ocean Green for the undercarriage and blade, Peacock Green for the work equipment and canopy, Citrus Green for the side covers, Dark Olive Gray for the floor and levers, and Smoke Gray for the control cover top and monitor box. Each color comes with its own paint part number for 16‑liter cans, 4‑liter cans, and spray cans. Need to touch up a scratch on the bonnet? You know exactly which spray can to order: part number 977620-30991 for Yanmar Citrus Green. That level of detail keeps a machine looking professional and holds resale value. I’ve restored a dozen backhoes – the right color match makes a difference.

Wiring Diagrams: Two Factory Schematics on Pages 4 and 5

Wiring is where most DIY guys get burned. Aftermarket diagrams often miss the fuse arrangement or the engine ground location. This catalog includes two pages of wiring diagrams, labeled (1) and (2). Page 4 of the PDF shows the fuse connections – 10A for stop/blade/grapple/swing/timer, 15A for oil pressure/glow plug/relay, 20A for backup/tail, nutlock switch, and so on. It also marks the engine ground point. If you’re troubleshooting an electrical issue, having the factory wire routing saves you from chasing ghosts. Use this in combination with the Automotive Industry Overview to understand common practices, but stick to this diagram for the actual connections.

Model Identification: B2U-1, 3TNE74-N3AY, and 3TNE74-EN3AY

One mistake I see a lot: ordering a part for the wrong engine serial range. The catalog breaks the models down cleanly. Section I (Vehicle) covers the B2U-1 from machine number 30501 onward, built November 1998 and later. Section II (Engine) has two columns: the 3TNE74-N3AY from engine number N00177 (Nov. 1998) and the 3TNE74-EN3AY from engine number N04808 (April 2000). The parts are specific to each. If you have an early 1998 machine with the N3AY, you can’t swap in ignition parts from the EN3AY without checking the catalog first. The 280 pages are organized by these sections, with a Picturesque Index (four separate index sections) to help you locate the right illustration. Ammann Yanmar B12 B17 Parts Catalog and Yanmar YB271, B27 1994 Parts Catalog – OEM Factory Specs are related machines that use similar components, but this catalog is for the B2U-1 specifically.

Why the 2001 Yanmar B2U-1 Parts Catalog Is Your Only Choice

Aftermarket catalogs and online parts databases often have transcription errors – they misplace a digit or use a superseded part number. This is the first revised edition, so it supersedes the earlier 1999 edition. It contains updates that Yanmar released during production. You get the painted color table, paint part numbers, wiring diagrams, and all sectioned part illustrations. The catalog uses simplified drawings, but every callout matches a genuine Yanmar part number. For example, the wiring diagram on page 4 shows the fuse ratings exactly as Yanmar specified. If you’re restoring a B2U-1 or keeping it in daily service, you need this PDF on your tablet or in your shop computer. Avoid the guesswork – use the factory data. Yanmar YB301 YB351 1991 Parts Catalog – 248 Pages OEM covers older models, but the B2U-1 is its own animal.

Q: Is this a service repair manual?

No, it’s a parts catalog. Use it to order parts only. For service procedures, get the factory service manual.

Q: How do I find the correct part number for my specific engine serial number?

Look at the model identification table on page 1 of the catalog. It lists the engine model, serial number range, and the section you should reference. For example, if your engine is a 3TNE74-EN3AY with serial N04808 or higher, you go to Section II (Engine). Then use the Picturesque Index to find the exploded view of the part group you need – say, the fuel system or the cylinder head. Each illustration has part numbers and callouts. Cross-check with the paint color chart if the part is a painted exterior component. This catalog covers the full machine, so spend a few minutes learning the index layout. It’ll save you an hour of flipping pages.

You can’t afford to guess when parts cost this much. The information you need is here – factory paint codes, wiring diagrams, and thousands of OEM part numbers. Automotive Industry Overview might give you background, but this catalog gives you the specifics. Access the Factory Manual.