Description

Yanmar 4JH-DT, 4JH-DTZ, 4JH-D1 Parts Catalog

If you’re tearing down a 4JH-DT or swapping a cylinder on a 4JH-D1, you need the right part numbers the first time. Guessing costs you a week waiting for the wrong fuel injector pump and a second week for the right gasket set. I’ve seen it. This is the official Yanmar Parts Catalog – 69 pages, OEM print, direct from the factory. No aftermarket reprints, no fuzzy scans. You get the same exploded diagrams and part number lists that Yanmar dealers use. That’s the only thing I’ll put on my workbench.

What This 69-Page Parts Catalog Actually Covers

Every major assembly on these engines is broken down into a standalone section. The table of contents runs from Cylinder Block (section 1) through Gasket Set (section 59). You’ll find dedicated chapters for the Camshaft (section 16), Crankshaft & Flywheel (section 17), and Piston & Connecting Rod (section 18). The fuel system gets its own coverage: Fuel Injection Pump (section 32), Fuel Feed Pump, Injection Valve, and Pipes. The cooling side includes Sea Water Pump, Fresh Water Pump, and Thermostat. If you need an oil dipstick or a bilge pump, those are listed too, with optional part callouts. Each section shows an exploded view and a parts list with reference numbers, level indicators, and interchangeability marks (N, Q, R, S, etc.). That’s how you know whether a new part can be swapped backward.

Decoding the Parts List: Level, Interchangeability, and Effective Machine Numbers

The manual includes a full explanation of how the parts list works – page 2 lays it out. Level numbers show parent-child relationships in assemblies. Interchangeability marks tell you if a new part can replace the old one and vice versa. For example, an “R” mark means the new part is interchangeable both ways. An “S” means neither direction. The Effective Machine Number column identifies exactly which engine serial numbers the part applies to. That’s critical when you’re ordering a fuel injection pump for a 4JH-DTZ that has an oil compensator type. The OCR excerpt shows notes: “Optional part. To E/#00155 (4JH-DT,4JH-DTZ)”. That kind of detail keeps you from buying the wrong pump.

3 Reasons to Use OEM Documentation Instead of Aftermarket Databases

First, aftermarket parts websites mix up part numbers between models constantly. I’ve caught them listing the same injector nozzle for a 4JH-D1 and a completely different Yanmar engine. Second, aftermarket databases don’t show interchangeability marks – you can’t tell if the new part number supersedes the old one or if it’s a straight swap. Third, they rarely include optional equipment sections. This catalog has every optional: mixing elbow, bilge pump (DX type), generator, special tools, gasket sets. You miss those in a generic search and you’re ordering from memory – which is how fuel return pipes get swapped with fuel feed pipes.

The same applies to online forums. Someone might post a part number that worked on their boat, but their engine might have a different effective machine number. This catalog gives you the authoritative answer. Automotive Industry Overview That Wikipedia article covers how standardized documentation like this came to be. Automotive Industry Overview

Cylinder Block and Gear Housing: Where Most People Get It Wrong

Section 1 covers the cylinder block. Section 2 and 3 cover gear housings – but note the model differentiation: (2GM20, C-YEU) versus (2GM20F, FC-YEU). If you don’t know your exact engine variant, you’ll order the wrong gear housing gasket set. The parts list includes part numbers for bolts, dowel pins, and seals. Same for the flywheel housing (section 4) and lub oil sump (section 5). I’ve seen a mechanic try to fit a 4JH-D1 oil pan onto a 4JH-DT because the aftermarket catalog said they were the same. They weren’t. This manual shows the exact part numbers for each model variant in columns A through F. No guesswork.

How to Use the Parts Index to Find Anything Fast

The back of the catalog has a PartsNo Index – an alphabetical/numerical listing of every part number in the book, cross-referenced to the section and reference number. If you’ve got a part in hand with a worn number, flip to the index and find which illustration it belongs to. Then go to that section and verify the description and interchangeability. That saves you from ordering blind. For example, the fuel injection pump assembly (section 32) lists the main pump as 739985-5100, with sub-components like the gasket (129478-51040) and bearing roller (122710-51050). The index will tell you exactly where those sub-parts live.

Related Manuals You Might Need

• Yanmar 4JH-DT Series Engine Parts Catalog 1997
• Yanmar TL150 4JH Series Engine Parts Catalog
• Yanmar 4JH-DT 4JH-DTZ 1997 Parts Catalog

Frequently Asked Questions

Does this catalog include torque specs for the cylinder head?

No. This is a parts catalog, not a service manual. It shows exploded views and part numbers, not torque values or repair procedures. You need the separate Yanmar service manual for torque specs.

Can I use this catalog to order parts for a 4JH-D1 with a different serial number range?

Yes, as long as the effective machine number range covers your engine. Check the column (A) for 4JH-D1 – if your serial number falls within the range noted (e.g., E/R numbers), the parts are correct. The manual includes change marks and notes like “To E/#00155” to indicate when a part was changed.

Does this catalog cover the optional bilge pump?

Yes. Sections 22 and 23 cover bilge pumps: STD/OPTIONAL and DX/OPTIONAL, with separate part numbers for each. Don’t confuse them – the DX pump uses different hardware.

What is the difference between level 1 and level 2 in the parts list?

Level 1 items are main assemblies (e.g., the entire fuel injection pump). Level 2 items are sub-components that make up that assembly (e.g., the gasket, bearing, retainer). The hierarchy helps you order the whole assembly or just the specific piece you broke.

If you’re serious about keeping your engine running without ordering the wrong part twice, this is the document you need. Access the Factory Manual and keep it on your shop tablet or print it for the workbench. Your parts counter will thank you.