Part of the Yanmar Repair Manuals.
Set the cylinder head of a 3JH2LE on the bench and two numbers decide what happens next: the bore limit and the head bolt torque sequence. This Yanmar service manual, factory publication A0A5053, puts both in front of you for the 3JH2LE and 4JH2LE marine diesel engines, 213 pages of specifications, clearances, and step by step disassembly and reassembly.
It walks the whole engine: cylinder block and head measurement, pistons, crankshaft and main bearings, fuel injection pump and governor overhaul and adjustment, turbocharger, lubrication, sea water and fresh water cooling circuits, and the electrical system with wiring diagrams. When the engine is apart and there is nobody to call, this is the reference that answers the question you are standing over.
As a PDF it travels with you, on a laptop at the bench, on a tablet in the engine bay, or printed page by page as you work.
What's Inside This Yanmar 3JH2L / 4JH2L Series Manual
| System | Pages | Key Topics |
|---|---|---|
| Capter 1 General | 5-19 | Engine Specifications, Engine Cross Section, Engine Outline, Piping Diagrams, Wiring Diagram |
| Capter 2 Basic Engine | 20-49 | Cylinder Block, Cylinder Head, Piston and Piston Pins, Connecting Rod, Crankshaft Adn Main Bearing, Camshaft and Tappets, Timing Gear, Flywheel and Housing |
| Capter 3 Fuel Injection Equipment | 50-95 | Fuel Supply System, Disasesmbly, Reassembly and Inspection of Governor, Disassembly, Reassembly and Inspection of Fuel Injection Pump |
| Intake and Exhaust System | 96-133 | Intake Silencer, Intake Manifold, Exhaust Gas Turbocharger, Mixing Elbow, Breather |
| Lubrication System | 134-144 | Lube Oil Pump, Lube Oil Filter, Oil Pressure Control Valve, Lube Oil Cooler (Applicable Engine Model 4JH2L-Ht), Piston Cooling Nozzle |
| Cooling System | 145-160 | Cooling Water System, Sea Water Pump, Fresh Water Pump, Heat Exchanger, Pressure Cap and Sub Tank, Thermostat |
| Electrical System | 161-180 | Starter Motor, Alternator, Regulator, Warning Devices, Air Heater |
| Disassembly and Reassembly | 181-212 | Disassembly and Reassembly Precautions, Disassembly and Reassembly Tools, Bolt/Nut Tightening Torque, Test Running |
Quick Reference Specifications
| Specification | Value | Page |
|---|---|---|
| Cylinder head bolts tightening torque (First) | 3.5 - 4.5 kgf·m (25.32 - 32.55 ft·lb) | p. 29 |
| Connecting rod tightening torque | 4.5-5.0 kgf·m (32.5-36.1 ft·lb) | p. 36 |
| Governor weight nut tightening torque | 4.5-5.0 kgf·m (32.54-36.16 ft·lb) | p. 68 |
| Delivery valve holder tightening torque | 3.5-4.0 kgf·m (25.31-28.93 ft·lb) | p. 81 |
| Fuel injection nozzle starting pressure | 195-205 kgf/cm² (2773-2915 lbs/in.²) | p. 90 |
| Hole type nozzle nut tightening torque | 4-4.5 kgf·m (28.9-32.5 ft·lb) | p. 92 |
| Seawater impeller width (Standard) | 31.6-31.8 mm (1.2441-1.2519 in.) | p. 150 |
| Seawater impeller clearance at assembly | 0-0.3 mm (0-0.0118 in.) | p. 150 |
| Heat exchanger test pressure | 2 kgf/cm² (28.44 lb/in.²) | p. 156 |
| Oil filter replacement period | Every 300 hours of engine operation | p. 141 |
| Fuel pump delivery valve holder tightening torque | 3.5-4.0 kgf·m (25.31-28.93 ft·lb) | p. 81 |
| Thermostat opening temperature | 75-78°C (167-174°F) | p. 160 |
Yanmar 3JH2L / 4JH2L Series Common Problems This Manual Covers
Cranks but will not fire, white smoke
Sediment in the fuel supply clogs nozzles and delivery valves, and the engine spins without lighting off. The manual covers disassembly, inspection, and adjustment of the injection pump, governor, feed pump, and nozzles, plus a fuel system troubleshooting section.
Manual Section: Fuel Injection Equipment p. 50Overheating under load
Coolant is full but temperature climbs the moment you load the engine, usually a worn sea water impeller or a fouled heat exchanger. This chapter covers the sea water pump, fresh water pump, heat exchanger, thermostat, and pressure cap.
Manual Section: Cooling Water System p. 145Blue smoke and rising oil consumption
High hour engines burn oil past worn rings and liners. The manual gives measurement procedures and wear limits for the cylinder block, pistons and pins, connecting rods, and crankshaft and main bearings, so you know what to replace before reassembly.
Manual Section: Basic Engine p. 20Low oil pressure warning
A flickering oil pressure alarm can be a tired pump, a sticking control valve, or internal wear. This chapter covers the lube oil pump, filter, oil pressure control valve, oil cooler, and piston cooling nozzles.
Manual Section: Lubrication System p. 134Slow cranking or charging failures
Marine electrics corrode, and a lazy starter or a dead alternator strands the engine. The Electrical System chapter covers the starter motor, alternator, regulator, air heater, and the warning devices that drive the alarms.
Manual Section: Electrical System p. 161Power loss from a fouled turbocharger
Carbon in the turbocharger and exhaust path chokes the engine long before anything actually breaks. This chapter covers the exhaust gas turbocharger, intake silencer and manifold, mixing elbow, and breather.
Manual Section: Intake and Exhaust System p. 96Reassembly without the torque figures
An engine goes back together in a fixed order at fixed torques, and guessing either one costs a gasket or a bearing. This chapter gives the full disassembly and reassembly sequence, the required tools, the bolt and nut torque table, and test running.
Manual Section: Disassembly and Reassembly p. 181Frequently Asked Questions
Which engines does this service manual cover?
It covers the Yanmar 3JH2LE and 4JH2LE marine diesel engines. This is factory publication A0A5053, a 213 page service manual with specifications, piping diagrams, wiring diagrams, and overhaul procedures for the complete engine.
Does it include torque specs for a rebuild?
Yes. The Disassembly and Reassembly chapter includes a bolt and nut tightening torque table. The cylinder head bolts are a two-stage tightening, not one pull: 3.5 to 4.5 kgf-m first (page 29), then 7.5 to 8.5 kgf-m final for the M10 x 1.25 bolts (page 211). Main bearing bolts, the reassembly sequence and the test running procedure are in the same chapter. p. 181
Can I overhaul the injection pump and governor with it?
Yes. The Fuel Injection Equipment chapter covers disassembly, reassembly, and inspection of both the injection pump and governor, their adjustment, the fuel feed pump, injection nozzles, and fuel system troubleshooting. Fuel injection pressure is specified at 200 plus or minus 5 kgf/cm2. p. 50
Does it cover the raw water cooling side?
Yes. The Cooling Water System chapter covers both circuits: the sea water pump, fresh water pump, heat exchanger, pressure cap and sub tank, and thermostat, which is where you go when the engine overheats under load. p. 145
Is this Service Manual a digital download?
Instant PDF download. You get the full 213-page searchable Service Manual immediately after payment. Open it on your laptop, tablet, or phone right in the shop.
Am I able to print pages from this manual?
Yes. The PDF has no DRM restrictions, so print any page or section you need for your shop. Works with any standard printer.
Does this Service Manual have electrical diagrams?
Yes. The wiring diagram is on page 14, printed in Chapter 1 General alongside the piping diagrams, the engine cross section and the engine outline, and it includes the wire colour code table.
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