Description

Yanmar B50-2B, 4TNE88-B1, 4TNE88-EB1 2002 Parts Catalog

If you’re tearing down a Yanmar B50-2B backhoe and hoping that some aftermarket parts list will get you the right seal kit or hydraulic line, I’ve got bad news: you’re going to waste time and money. I’ve seen guys order a boom cylinder rebuild kit from a generic catalog only to find the O-ring groove is off by a millimeter. That’s a half-day lost, plus the cost of the wrong parts. This is a factory Parts Catalog – not a service manual, but the one document that tells you exactly which Yanmar part number fits what. It covers the B50-2B machine and the 4TNE88-B1 and 4TNE88-EB1 engines from 2002 and production starts back to 1997. 147 pages of exploded diagrams, paint codes, and the Wiring diagram that every electrical gremlin chaser needs. You don’t guess part numbers. You look them up.

Picturesque Index: Main Parts Breakdown

This catalog opens with a “PICTURESQUE INDEX” that groups parts by location on the machine – main parts, hydraulic section, and then figure numbers for each assembly. The first index (MAIN PARTS) lists everything from the inlet house and exhaust pipe (Figure 2) to the boom bracket (Figure 52). Want the fuel tank assembly? Figure 5. The control valve group? Figures 33 and 34. You don’t flip through 147 pages blind; you start with the index, find your figure number, and turn there. Each figure shows a line drawing with callouts that match a part number table. That table gives you the official Yanmar part number, the description, and the quantity used. For a shop that’s rebuilding a B50-2B undercarriage or putting a new swing motor in, this index cuts the part‑hunting time to zero.

Hydraulic Section: Cylinders and Control Valves

The second picturesque index focuses on the hydraulic section. It maps every cylinder – boom, arm, bucket, blade (Figures 24–28) – and the travel motor (Figure 29), swivel joint (Figure 31), and the control valve (Figures 32–34). If you’re replacing a hose or resealing a cylinder, you need the exact part number for the seal kit or the gland nut. Aftermarket catalogues often consolidate parts across models and get the bore size wrong. This Parts Catalog gives you the factory breakdown. The hydraulic oil tank is Figure 39; the oil cooler is wrapped into Figure 5 with the radiator. That kind of grouping is typical of OEM documentation – they know what a tech actually looks at on the bench.

Wiring Diagram: Electrical System

Page references aren’t listed for every item, but the wiring diagram is its own section at the end of the catalog. When you’ve got a B50-2B that won’t crank or the work lights go dead, you need the factory wire colors and connector locations. Aftermarket wiring schematics often omit the ground points or swap pin assignments. This diagram is the same one the Yanmar engineers used to build the machine. It shows the battery (Figure 7), the electric parts (Figure 8), and the work lamp (Figure 9). For a home garage mechanic who’s not used to reading injection harnesses, having the actual OEM drawing saves you from back‑probing the wrong terminal and frying a control module.

Painted Color List and Paint Part Numbers

One section that surprises most DIYers is the “PAINTED COLOR LIST” with Munsell number and color code. If you’re restoring an old B50-2B and want the paint to match, you don’t go to a body shop and say “Yanmar orange.” You give them the Munsell code from this catalog. There’s also a list of “PAINT PART No,” which are the actual Yanmar spray can or touch‑up bottle part numbers. That kind of detail is typical of factory catalogs and completely absent from third‑party summaries. A quick note from the preface: “Be careful not to use the simple parts available in the market, otherwise their use in repairing causes such as an early breakage.” Yanmar doesn’t mince words – neither do I. Stick with factory parts numbers.

Source Validity: Why OEM Factory Documentation Matters

This catalog is the 1st revised edition (published June 2002) with parts catalog number 00OY00S3671. It supersedes the 1997 edition (00OY00S3670). That matters because part numbers change. If you order a hydraulic pump rebuild kit using an old number, you might get the wrong displacement. The preface makes it clear: this is not a service procedure manual – it’s a parts identification tool. For actual repair steps, you’d need the corresponding Yanmar service manual. But for ordering the correct components from the dealer or online, this Parts Catalog is the only source that guarantees your order matches the build sheet. I’ve seen enough mismatched swing motors on these backhoes to tell you that relying on aftermarket cross‑references is a gamble. If you need the part, look it up here first.

Frequently Asked Questions

Does this catalog include torque specs or service procedures?

No. It is a parts identification catalog, not a repair manual. It contains exploded diagrams, part numbers, quantities, and paint codes. For torque values and assembly instructions, you need the Yanmar B50-2B service manual.

Can I use this to order parts for a different Yanmar model?

The catalog covers the B50-2B machine and the 4TNE88-B1 and 4TNE88-EB1 engines specifically. Some parts may be shared across models, but the part numbers are unique to this series. Cross‑referencing is risky – you might get a component that doesn’t fit. The index includes separate sections for the engine and vehicle, so if you have a 4TNE88 engine in a different chassis, the engine parts may apply, but the chassis parts (boom, bucket, control valve) will not. Check the figure numbers carefully.

You’ve got a backhoe to get back to work. Stop flipping through generic parts listings and start using the same document the dealer’s parts counter uses. Yanmar B50-2B C B50-2B P 2000 Parts Catalog – OEM Specs covers a similar machine if you need an earlier revision. Also check Ammann Yanmar B12 B17 Parts Catalog for smaller Yanmar equipment, or Yanmar YB271, B27 1994 Parts Catalog – OEM Factory Specs for a different line. For context on why OEM documentation matters across the industry, see Automotive Industry Overview and Automotive Industry Overview. Access the Factory Manual now and get the part numbers you need without the guesswork.