Part of the Yanmar Repair Manuals.
Lay a strip of plastigage on a crank journal of a 4JH2 and you need one number before the cap goes back on: 0.038 to 0.093 mm oil clearance, with a 0.25 mm wear limit. That figure sits on page 54 of this Yanmar service manual, the factory reference for the 4JH2E, 4JH2-TE, 4JH2-HTE, 4JH2-DTE and 4JH2-UTE marine diesel engines.
Across 406 pages it works through the basic engine parts, the fuel injection pump and governor, the turbocharger, the lubrication and cooling water systems, the reduction and reversing gear, and the electrical system, with a full disassembly and reassembly chapter closing it out. Wear limits, clearances and tightening torques are tabulated where you measure them.
Guessing a bearing clearance or a torque figure costs you a second teardown, or a ruined crank. The PDF downloads instantly and carries 112 bookmarks, so the spec you need is a click away.
What's Inside This Yanmar 4JH2 Series Manual
| System | Pages | Key Topics |
|---|---|---|
| History of Revision | 3 | Injection Timing Changed, Tightening Torque of Bolts and Nuts for General Use, Tightening Torque of Nut for Remote Control Cable Connection of Clutch Shifting Lever |
| General | 6-32 | Exterior Views, Specifications, Performance Curves, Engine Cross Section, Dimensions, Piping Diagrams |
| Inspection and Servicing of Basic Engine Parts | 33-64 | Cylinder Block, Cylinder Liners, Cylinder Head, Piston and Piston Pins, Connecting Rod, Crankshaft and Main Bearing, Camshaft and Tappets, Timing Gear |
| Fuel Injection Equipment | 65-163 | 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 | 164-182 | Turbocharger, Mixing Elbow |
| Lubrication System | 183-195 | Lube Oil Pump, Lube Oil Filter, Oil Pressure Control Valve, Lube Oil Cooler, Piston Cooling Nozzle, Rotary Waste Oil Pump (Optional) |
| Cooling Water System | 196-214 | Sea Water Pump, Fresh Water Pump, Heat Exchanger, Pressure Cap and Sub Tank, Thermostat, Kingston Cock (Optional) |
| Reduction and Reversing Gear | 215-303 | Installation, Operation and Maintenance, Servicing, Disassembly, Reassembly, Special Tools, Shifting Device |
| Remote Control (Optional) | 304-310 | Remote Control System, Remote Control Installation, Remote Control Inspection, Remote Control Adjustment |
| Electrical System | 311-368 | Battery, Starter Motor, Alternator, Instrument Panel, Warning Devices, Air Heater (Optional) |
| Disassembly and Reassembly | 369-404 | Disassembly and Reassembly Precautions, Disassembly and Reassembly Tools, Bolt/Nut Tightening Torque, Test Running |
Quick Reference Specifications
| Specification | Value | Page |
|---|---|---|
| Oil pressure control valve regulating pressure | 3.5 ~ 4.5 kg/cm² (49.78 ~ 64.00 lb/in.²) | p. 191 |
| Main bearing cap bolt tightening torque | 10.5 ~ 11.5 kg-m (75.92 ~ 83.16 ft-lb) | p. 55 |
| Main bearing oil clearance (Crank journal and bushing oil clearance) | Standard: 0.038 ~ 0.093 mm (0.0014 ~ 0.0036 in.), Wear limit: 0.25 mm (0.0098 in.) | p. 54 |
| Connecting rod bolt tightening torque | 5.0 ~ 5.5 kg-m (36.15 ~ 39.77 ft-lb) | p. 51 |
| Oil pressure alarm operating pressure | 0.1 ~ 0.3 kg/cm² (1.422 ~ 4.266 lb/in.²) | p. 350 |
| Fuel Injection Pump Injection Starting Pressure | 195 ~ 205 kg/cm² | p. 66 |
| Lube Oil Filter Discharge Volume | 30 L/min | p. 189 |
| Oil Pressure Regulating Pressure | 3.5 ~ 4.5 kg/cm² | p. 191 |
| Thermostat Opening Temperature | 75 ~ 78°C | p. 210 |
Yanmar 4JH2 Series Common Problems This Manual Covers
Low oil pressure warning at idle
A flickering oil pressure alarm on a hot 4JH2 usually starts an argument between bearings, pump and relief valve. The lubrication chapter covers the lube oil pump, oil pressure control valve (regulating pressure 3.5 to 4.5 kg/cm2) and lube oil cooler so you can rule each one out in order.
Manual Section: Chapter 5 Lubrication System p. 183Worn main and rod bearings
Once low oil pressure points below the pan, you need clearances, not opinions. This chapter gives crank journal oil clearance and wear limits, plus main bearing cap and connecting rod bolt torques, so the bottom end goes back together to spec.
Manual Section: Chapter 2 Inspection and Servicing of Basic Engine Parts p. 33Hard starting and smoky exhaust
Tired injection nozzles and drifted pump settings show up as long cranking, knock and dirty exhaust. The fuel injection chapter covers pump service data, governor adjustment, nozzle inspection and an injection starting pressure of 195 to 205 kg/cm2, with its own troubleshooting table.
Manual Section: Chapter 3 Fuel Injection Equipment p. 65Lost boost on turbocharged models
On the 4JH2-TE, 4JH2-HTE and 4JH2-DTE, fading boost or a new whine means the turbocharger and mixing elbow need attention. This chapter covers turbocharger inspection and servicing along with the intake and exhaust plumbing around it.
Manual Section: Chapter 4 Intake and Exhaust System p. 164Engine overheating on the raw water side
A failed sea water pump impeller or a scaled heat exchanger will cook a fresh-water-cooled engine quickly. The cooling chapter covers the sea water pump, fresh water pump, heat exchanger, pressure cap and a thermostat that should open at 75 to 78 degrees C.
Manual Section: Chapter 6 Cooling Water System p. 196Rough or slipping gear engagement
Clunky shifts or slip under load point at the reduction and reversing gear rather than the engine itself. This chapter runs from construction and maintenance through full disassembly, servicing and reassembly, including the shifting device and its special tools.
Manual Section: Chapter 7 Reduction and Reversing Gear p. 215Slow cranking and charging faults
Slow cranking, a dead panel or a battery that never comes up can hide in several places. The electrical chapter covers the battery, starter motor, alternator, instrument panel and warning devices so you can test each link in the circuit.
Manual Section: Chapter 9 Electrical System p. 311Frequently Asked Questions
Which Yanmar engines does this service manual cover?
It covers the Yanmar 4JH2 series marine diesel engines: 4JH2E, 4JH2-TE, 4JH2-HTE, 4JH2-DTE and 4JH2-UTE. The manual applies whether the engine is in the boat or out on a stand, and it also covers the matching reduction and reversing gear.
Does it include torque specs and bearing clearances?
Yes. The Basic Engine Parts chapter tabulates clearances and torques, for example main bearing cap bolts at 10.5 to 11.5 kg-m, connecting rod bolts at 5.0 to 5.5 kg-m, and crank journal oil clearance of 0.038 to 0.093 mm with a 0.25 mm wear limit. p. 52
What is the injector pop pressure on the Yanmar 4JH2 Series marine diesel engine?
The Fuel Injection Equipment chapter lists an injection starting pressure of 195 to 205 kg/cm2, and covers disassembly, inspection and adjustment of the injection pump, governor and nozzles so you can set it.
Does it cover the marine gear, not just the engine?
Yes. Chapter 7, Reduction and Reversing Gear, covers construction, installation, operation and maintenance, servicing, full disassembly and reassembly, special tools and the shifting device. The optional remote control system has its own chapter after it. p. 215
How will I receive this Service Manual?
This is a 406-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.
Can I print specific sections of this Service Manual?
No restrictions at all. Print individual pages, full chapters, or the entire manual. The PDF is completely unlocked.
Does this Yanmar 4JH2E & variants manual include wiring diagrams?
Included. The Yanmar 4JH2E & variants Service Manual covers complete wiring harness diagrams, electrical circuits, and connector pinouts.
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