Description

Yanmar 4JH-DT, 4JH-DT2 Parts Catalog – Factory OEM Specs for Marine Diesel Engines

Ever had a parts counter guy hand you the wrong piston ring because the aftermarket catalog grouped four different engine families together? That’s the kind of lost time that makes me want to throw a wrench. This Yanmar 4JH-DT, 4JH-DT2 Parts Catalog is the actual factory document – 42 pages printed from the same plates Yanmar uses. No reprints, no third-party guesswork. If you’re rebuilding a 4JH-DT or 4JH-DT2 marine diesel and need the exact part number for a crankshaft or a valve, this is the only source you should trust. I’ve torqued enough head bolts to know that one wrong gasket thickness can cost you an afternoon of rework. Get the right part the first time.

What This Parts Catalog Actually Covers

Open this catalog and you get a full breakdown of every major assembly on the 4JH-DT and 4JH-DT2. The table of contents lists: CYLINDER BLOCK, GEAR HOUSING, FLYWHEEL HOUSING & OIL SUMP, CYLINDER HEAD & BONNET, SUCTION MANIFOLD & AIR CLEANER, EXHAUST MANIFOLD & SILENCER, CAMSHAFT & DRIVING GEAR, CRANKSHAFT & PISTON, LUB.OIL SYSTEM, COOLING WATER SYSTEM, FUEL INJECTION PUMP, GOVERNOR, FUEL INJECTION VALVE, FUEL LINE, STARTING MOTOR, GENERATOR, and GASKET SET. That’s 18 sections covering the entire engine from the oil pan up to the valve cover. Each section shows exploded diagrams with reference numbers tied to a parts list that includes Yanmar part numbers, descriptions, and quantities. You don’t have to wonder if a part fits – the catalog tells you exactly which engine serial numbers it applies to.

The catalog also includes a NUMERICAL INDEX at the back. If you have a part number from a scrapped engine, you can look it up and see all the assemblies it belongs to. That’s a time-saver when you’re sourcing used parts or verifying interchangeability.

How to Read the Yanmar Parts Catalog – Page 1 is Critical

Most people skip the front matter. Don’t. Page 1 contains the “How to read this Parts Catalog” section that explains the level marks, change marks, and compatibility symbols. For example, a symbol of “N” means the new part is backward-compatible but not forward. “R” means no compatibility either way. If you miss that, you might order a fuel injection pump that looks identical but won’t bolt to your 4JH-DT2 with the boost compensator. The catalog also shows a REMARKS table that lists optional parts – the 4JH-DT and 4JH-DT2 with boost compensator are explicitly noted. Page 1 is dense, but it’s the key to using this catalog without screwing up.

Why OEM Part Numbers Beat Aftermarket Guessing

Aftermarket catalogs often group the 4JH-DT with the 4JH-DTE or even the 3TNV88 engines. That’s a recipe for getting a camshaft that fits but has a different lobe profile. The Yanmar Parts Catalog is engine-specific. Every part number is tied to the exact model and serial number range. For the 4JH-DT and 4JH-DT2, you get the actual OEM part numbers that match the parts diagram. No cross-referencing needed. When you’re ordering a cylinder head gasket or a set of valves, you want the factory spec – not a “universal” gasket that’s 0.5 mm too thick. I’ve seen that cause compression loss and overheating. Stick with the factory document.

Camshaft and Crankshaft – Critical Matching

The CAMSHAFT & DRIVING GEAR and CRANKSHAFT & PISTON sections are where most rebuilders get burned. This catalog provides the exact part numbers for the camshaft gear and crankshaft gear, including the timing marks. If you’re replacing the camshaft, you need to know which keyway variant your engine has. The catalog lists the part numbers by engine serial number (E/# range). For example, the fuel injection pump section shows that the boost compensator type applies to 4JH-DT, 4JH-DT2 up to E/#00155. That level of specificity prevents ordering the wrong gear. Plus, the crankshaft section shows the piston ring set part numbers and the connecting rod bearing sizes. You can verify the undersize options if you’re grinding the crank. That’s the kind of data you won’t find in a generic parts book.

Fuel Injection System – Boost Compensator Details

If your 4JH-DT2 has a boost compensator (often for turbo applications), the catalog dedicates a separate fuel injection pump diagram. The OCR excerpt shows “FUEL INJECTION PUMP (W/BOOST)” with part numbers like 729995-51390 and 729995-51391. The difference between the two is likely a calibration change – the catalog notes that they are optional parts limited to specific engine serial numbers. You also get the gasket (122710-51540) and roller bearing (122710-51560) for the pump. Without this catalog, you’d be guessing which pump your engine needs. That’s a thousand-dollar mistake waiting to happen.

FAQ

Does this parts catalog include torque specs or service procedures?

No. This is strictly a parts catalog – exploded diagrams and part numbers only. For service procedures, you need the Yanmar workshop manual. But you can cross-reference the part numbers to the service manual’s illustrations.

Will this work for a 4JH-DTE?

This catalog covers 4JH-DT and 4JH-DT2. The 4JH-DTE has a different cylinder block and fuel system. You need the specific catalog for that model. Check our Yanmar 4JH-DT Series Engine Parts Catalog 1997″>Yanmar 4JH-DT Series Engine Parts Catalog 1997 for additional coverage.

Source Authenticity – This Is the Real OEM Document

What you’re getting is the original factory PDF – the same one Yanmar dealers use. It’s not a scan of a scan. The OCR text is clean, the diagrams are sharp, and all compatibility tables are legible. I’ve seen aftermarket parts catalogs that list a generic “valve” without specifying whether it’s intake or exhaust. This catalog gives you the exact part numbers for intake and exhaust valves, valve guides, and seals. If you’re a shop owner, you can hand this to a junior tech and know they’ll order the right parts. That’s worth the price of the manual on the first job.

Related manuals you might need:
– Yanmar TL150 4JH Series Engine Parts Catalog”>Yanmar TL150 4JH Series Engine Parts Catalog
– Yanmar 4JH-DT 4JH-DTZ 1997 Parts Catalog”>Yanmar 4JH-DT 4JH-DTZ 1997 Parts Catalog

For broader context on marine diesel engineering, you can read the Automotive Industry Overview – but honestly, you don’t need that. You need the factory parts catalog. Automotive Industry Overview”>Automotive Industry Overview is background noise; this manual is the signal.

If you’re rebuilding a Yanmar 4JH-DT or 4JH-DT2 and want to avoid ordering the wrong valve, camshaft, or gasket set, Access the Factory Manual. It’s 42 pages of the only specs that matter – the ones Yanmar stamped into the original parts drawings. Stop wasting time at the parts counter. Get the OEM parts catalog and order with certainty.