Getting your marine diesel engine running right requires the exact 308-page Yanmar 3JH30A Service Manual PDF (OEM #0000A0A1015-9112), covering the complete 3JH2 Series including the 3JH2E, 3JH2-TE, and 3JH25A variants. Inside, you get complete wiring diagrams to track down electrical faults, plus step-by-step rebuild procedures for the fuel injection pump and cooling water system. Open to the troubleshooting charts to diagnose hard starts, or rely on the extensive clearance tables to rebuild your block right the first time. Verify your sea water pump impeller width measures exactly 31.6 to 31.8 mm, and lock down the cylinder head bolts to a final complete torque of 54.2 to 61.5 ft-lb. Don't risk blowing a head gasket on unverified internet advice. Download this bookmarked file right to your tablet and bring the factory answers directly to the engine room.
What's Inside This Yanmar 3JH2L / 4JH2L Series Manual
| System | Pages | Key Topics |
|---|---|---|
| General | 6-28 | 1.Exterior Views, 2.Specifications, 3.Engine Outline, 4.Performance Curves, 5.Piping Diagrams |
| Basic Engine Parts | 29-58 | 1.Cylinder Block, 2.Cylinder Head, 3.Piston and Piston Pins, 4.Connecting Rod, 5.Crankshaft and Main Bearing, 6.Camshaft and Tappets, 7.Timing Gear, 8.Flywheel and Housing |
| Fuel Injection Equipment | 59-98 | Fuel Injection Pump Service Data, Governor, Disassembly Reassembly and Inspection of Fuel Injection Pump, Fuel Injection Pump and Governor, Fuel Feed Pump, Fuel Injection Nozzle |
| Intake and Exhaust System | 99-117 | 1.Intake and Exhaust System, 2.Turbocharger, 3.Mixing Elbow |
| Lubrication System | 118-131 | 1.Lubrication System, 2.Lube Oil Pump, 3.Lube Oil Filter, 4.Oil Pressure Control Valve, 5.Lube Oil Cooler, 6.Piston Cooling Nozzle, 7.Rotary Waste Oil Pump(Optional) |
| Cooling Water System | 132-151 | 1.Cooling Water System, 2.Sea Water Pump, 3.Fresh Water Pump, 4.Heat Exchanger, 5.Pressure Cap and Sub Tank, 6.Thermostat, 7.Kingston Cock(Optional), 8.Sea Water Filter(Optional) |
| Reduction and Reversing Gear | 152-208 | Km3A (Construction, Shifting Device, Servicing, Disassembly, Reassembly), Km3P1, Km3P3, Km35P1 (Construction |
| Remoto Control | 209-215 | 1.Remoto Control System, 2.Remoto Control Installation, 3.Remoto Control Inspection, 4.Remote Control Adjustment |
| Electrical System | 216-271 | 1.Electricai System, 2.Battery, 3.Starter Motor, 4.Alternator, 5.Instrument Panel, 6.Warning Deices, 7.Air Heater(Optional), 8.Electric Type Engine Stop Device(Optional) |
| Disassembly and Reassembly | 272-307 | 1.Disassembly and Reassembly Precautions, 2.Disassembly and Reassembly Tools, 3.Disassembly and Ressembly, 4.Bolt/nut Tightening Torque, 5.Test Running |
Quick Reference Specifications
| Specification | Value | Page |
|---|---|---|
| Cylinder head bolt tightening torque (Partial) | 3.5 ~ 4.5 kg-m (25.3 ~ 32.5 ft-lb) | p. 295 |
| Cylinder head bolt tightening torque (Complete) | 7.5 ~ 8.5 kg-m (54.2 ~ 61.5 ft-lb) | p. 295 |
| Sea water pump impeller width (Standard) | 31.6 ~ 31.8 mm (1.2440 ~ 1.2519 in.) | p. 137 |
| Sea water pump wear plate thickness (Standard) | 2 mm (0.0787 in.) | p. 12 |
| Fuel filter filtering method | filter paper | p. 97 |
| Fuel filter filtering area | 840cm² (130.23in.²) | p. 97 |
| Alternator brush length (Maintenance standard) | 16 (0.6299) | p. 5 |
| Alternator brush length (Wear limit) | 9 (0.3543) | p. 12 |
| Lube oil filter filtration area | 800cm² (124in.²) | p. 127 |
| Lube oil filter discharge volume | 20 L/min (1220 in.³/min) | p. 127 |
| Number of cylinders | 3 | p. 10 |
| Bore x Stroke | 82 x 86 mm | p. 12 |
Yanmar 3JH2L / 4JH2L Series Common Problems This Manual Covers
Yanmar 3JH2 Series marine diesel engine rapid overheating and loss of raw-water flow. p. 137
Inspect the sea water pump components if flow drops. Measure the impeller width to ensure it is within 31.6 ~ 31.8 mm (1.2440 ~ 1.2519 in.) as shown on page 137. Replace the impeller if worn and check the wear plate thickness.
Manual Section: Cooling Water SystemEngine cranks over fine but starts hard with low compression and white smoke. p. 295
Check cylinder compression and inspect the exhaust elbow for water intrusion. If removing the head, torque the cylinder head bolts in sequence to a final value of 7.5 ~ 8.5 kg-m (54.2 ~ 61.5 ft-lb) according to page 295. Adjust valve clearances before restarting.
Manual Section: Disassembly and ReassemblyBattery drains quickly while running under load and alternator charge lamp stays illuminated. p. 249
Test output voltage at the battery terminals. Remove the alternator regulator assembly and measure the brush length. Replace the brushes if they wear down to the 9 mm (0.3543 in.) wear limit specified on page 249. Clean all slip rings and retest the charging circuit.
Manual Section: Electrical SystemSudden oil pressure alarm activation and visible oil loss during high RPM operation. p. 127
Verify engine oil level is within the 0.9 to 7.0 L capacity limits on the dipstick. Inspect the lube oil filter assembly on page 127, ensuring it maintains the correct 20 L/min (1220 in.³/min) discharge volume. Replace the filter and check the bypass valve spring.
Manual Section: Lubrication SystemEngine runs at high speed but lacks power at low speed with loud knocking. p. 97
Drain the water separator and inspect the primary fuel lines for air leaks. Replace the filter paper element every 300 hours as specified on page 97. Bleed the fuel system completely and verify injection pump timing if the knocking persists.
Manual Section: Fuel Injection EquipmentFrequently Asked Questions
What are the torque specs for the Yanmar 3JH2 cylinder head bolts?
The cylinder head bolts should be tightened in two steps. The first step requires a torque of 3.5 to 4.5 kg-m (25.32 to 32.55 ft-lb), and the second step requires a torque of 7.5 to 8.5 kg-m (54.25 to 61.48 ft-lb).
What is the specified injection starting pressure for the Yanmar 3JH25A and 3JH30A marine diesel engines?
For both the 3JH25A and 3JH30A models, the injection starting pressure is specified as 200 to 210 kg/cm² (165 to 175 kg/cm² for calibration).
What is the lubricating oil capacity for the Yanmar 3JH25A and 3JH30A engines?
The lubricating oil capacity for the 3JH25A and 3JH30A engines is 0.9 / 7.0 liters (Effect/max).
What are the capacities for the fresh water tank and sub tank in the Yanmar 3JH25A and 3JH30A cooling system?
The fresh water tank capacity is 4.4 liters, and the sub tank capacity is 0.8 liters for both the 3JH25A and 3JH30A models.
How quickly can I access this manual after buying?
This is a 308-page searchable PDF ready for immediate download. Works on any device, so pull it up on your phone while you're under the hood. No shipping, no waiting.
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.
Can I find wiring schematics in this Yanmar 3JH2 Series & variants manual?
Included. The Yanmar 3JH2 Series & variants Service Manual covers complete wiring harness diagrams, electrical circuits, and connector pinouts.
Document Quality
This document is a scanned PDF with an optical character recognition (OCR) layer, allowing you to search and copy the full text content. The text is crisp and generally easy to read throughout the manual. Diagrams and illustrations are mostly clear raster images, with labels that are readable. Pages are clean with no significant scan artifacts, stains, or skewed content. All pages contain relevant information, with no notable blank or filler pages.
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