Part of the Yanmar Repair Manuals.
This Yanmar 4LH series Service Manual is a 398 page factory workshop guide for the marine diesel engine family, covering the turbocharged variants such as the 4LH-TE, 4LH-HTE, 4LH-DTE, and 4LH-STE. It is written in English with a full text layer, so the content is searchable and printable.The engine is a four cylinder unit with 3.455 L displacement and a 16.4 compression ratio, and the manual documents both the distributor type and YPES-AL type fuel injection systems fitted across the range. You get complete disassembly and reassembly procedures for the basic engine, the fuel injection pumps and nozzles, the turbocharger and intake system, and the lubrication circuit.With specifications, torque values, and service data throughout, an owner or marine mechanic can carry out a full overhaul, an injection service, or routine maintenance without guessing.
What's Inside This Yanmar 4LH series Manual
| System | Pages | Key Topics |
|---|---|---|
| General | 7-29 | Exterior Views, Specifications, Service Data Sheet, Performance Curves, Dimensions, Piping Diagrams, Electrical Diagrams |
| Basic Engine | 30-68 | Disassembly and Reassembly Tools, Cylinder Block, Cylinder Liners, Cylinder Head, Piston and Piston Pins, Connecting Rod, Crankshaft and Main Bearing, Camshaft and Tappets |
| Distributor Type Fuel Injection | 69-124 | Fuel Supply System, Bleeding and Checking Injection Timing, Fuel Injection Pump Outline, Fuel System, Injection Pump Construction and Operation, Governing Mechanism |
| Ypes-Al Type Fuel Injection | 125-180 | Fuel Supply System, Disassembly, Reassembly and Inspection of Governor, Reassembly and Inspection of Fuel Injection Pump, Fuel Injection Pump and Governor |
| Intake Manifold | 184-196 | Tools, Troubleshooting, Service Data, Fuel Injection Pump Specifications, Intake and Exhaust System, Intake Silencer |
| Turbocharger | 197-228 | - |
| Breather | 229-237 | Mixing Elbow |
| Lube Oil Pump | 238-242 | Lubrication System |
| Rotary Waste Oil Pump (Optional) | 243-250 | Lube Oil Cooler, Lube Oil Filter, Oil Pressure Control Valve, Piston Cooling Nozzle |
| Sea Water Pump | 251-256 | Cooling Water System |
| Pressure Cap and Sub Tank | 257-263 | Fresh Water Pump, Heat Exchanger |
| Bilge Pump and Bilge Strainer (Optional) | 264-390 | Sea Water Filter (Optional), Thermostat, Kingston Cock (Optional) |
| Lubrication System | 391-398 | Lube Oil Pump, Lube Oil Filter |
Quick Reference Specifications
| Specification | Value | Page |
|---|---|---|
| Oil pressure alarm trigger point | below 0.3 kg/cm² (1.42 ~ 4.26 lb/in.²) | p. 397 |
| Cylinder head bolt tightening torque (4LH-TE, -HTE, -DTE) | 1st: 5 kg-m, 2nd: 10 kg-m, 3rd: 15 kg-m | p. 14 |
| Cylinder head bolt tightening torque (4LH-STE) | 1st: 11 kg-m, 2nd: 17 kg-m, 3rd: 19 kg-m | p. 14 |
| Fuel injection nozzle clamp nut tightening torque (4LH-TE, -HTE, -DTE) | 0.4 ~ 0.5 kg-m | p. 14 |
| Fuel injection nozzle clamp nut tightening torque (4LH-STE) | 0.6 ~ 0.7 kg-m | p. 14 |
| Fuel filter replacement interval | Every 50 hours operation | p. 123 |
| Lube oil filter replacement interval | Every 200 hours of engine operation | p. 397 |
| Fuel injection nozzle starting pressure | 195 ~ 205 kg/cm² (2773 ~ 2915 lb/in.²) | p. 122 |
| Fuel injection nozzle contact surface wear limit | 0.1 mm (0.0039 in.) | p. 121 |
| Intake silencer cleaning interval | Every 500 hours operation | p. 185 |
| Number of cylinders | 4 | p. 12 |
| Displacement | 3.455 L | p. 12 |
Yanmar 4LH series Common Problems This Manual Covers
Hard starting or no-start
Air in the fuel system, a clogged fuel filter, or injection timing that has drifted can leave a 4LH hard to start or running rough. The distributor type fuel injection section covers bleeding, timing checks, and pump service.
Manual Section: Distributor Type Fuel Injection p. 69Loss of power and black smoke
A restricted intake, a clogged exhaust, or a tired turbocharger show up as black smoke and lost power under load. This section covers the intake silencer, manifold, turbocharger, and mixing elbow.
Manual Section: Intake and Exhaust System p. 181Low oil pressure warning
A low oil pressure alarm points to low oil level, a clogged filter, or a worn lube oil pump. The lubrication system section covers the oil pump and filter service.
Manual Section: Lubrication System p. 391Injector spray faults and knock
Worn injection nozzles or an imbalanced pump cause combustion knock, vibration, and uneven running. The YPES-AL type section details nozzle inspection and pump and governor overhaul.
Manual Section: YPES-AL Type Fuel Injection p. 125Worn liners and blow-by
High hours bring cylinder liner and piston ring wear, which shows as blow-by and oil consumption. The basic engine section covers liners, pistons, connecting rods, and bearings.
Manual Section: Basic Engine p. 30Fuel contamination and filter clogging
Marine fuel picks up water and debris, clogging filters and causing shutdowns. The distributor type fuel injection section covers the fuel supply system and filter replacement.
Manual Section: Distributor Type Fuel Injection p. 69Frequently Asked Questions
Which engines does this manual cover?
It covers the Yanmar 4LH series marine diesel engine family, including turbocharged variants such as the 4LH-TE, 4LH-HTE, 4LH-DTE, and 4LH-STE. All share the four cylinder, 3.455 L block documented throughout.
Does it include torque specifications?
Yes. Torque values appear throughout, including main bearing cap and cylinder head figures. The basic engine section covers the block, crankshaft, and bearing torques. p. 30
Does it cover the fuel injection system?
Yes. Both fuel systems are documented: the distributor type covers supply, timing, and pump construction, and a separate section covers the YPES-AL type pump, governor, and nozzles. p. 69
Does it cover the turbocharger?
Yes. The intake and exhaust section covers the turbocharger along with the intake silencer, manifold, mixing elbow, and breather. p. 181
How will I receive this Service Manual?
You get a 398-page searchable PDF that downloads instantly after checkout. Open it on your laptop, tablet, or phone — bring it right to the shop floor.
Can I print specific sections of this Service Manual?
The PDF is DRM-free. Print whatever sections you need to take out to the shop. Standard letter or A4 paper works.
Are electrical wiring diagrams included in this Yanmar 4LH series manual?
Included. The Yanmar 4LH series Service Manual covers complete wiring harness diagrams, electrical circuits, and connector pinouts.
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