Yanmar JH4 Series Marine Diesel Engine Service Manual 2007 (P/N 0BJH4-G00102)

Yanmar’s JH4 Series Service Manual, P/N 0BJH4-G00102, covers 3JH4E, 4JH4AE, 4JH4-TE and 4JH4-HTE marine diesel engines. This is the July 2007 Rev. 2 release, which added the 4JH4AE.

Searchable PDF and Wiring Diagram Detail

Text search and diagram navigation: Searchable text and embedded PDF bookmarks provide access to the service sections. Small wiring-diagram labels require zooming to read comfortably.

392 pages in one printable English PDF, including the original cover, copyright page, two contents pages and 12 intentionally blank pages.

JH4 Engine Repair, Fuel Systems and Electrical Diagnosis

These selected service topics outline part of the manual’s coverage. Further topics include long-term engine storage and optional bilge-pump service.

• Engine repair: Step-by-step disassembly and assembly, compression testing, cylinder-head and bottom-end inspection, valve adjustment, and timing-gear checks.

• Fuel system: Supply and return-pressure tests, injection-pump replacement and timing, injector testing, filter replacement, and fuel-system bleeding.

• Cooling system: Pressure and thermostat tests, heat-exchanger service, seawater-pump repair, and intercooler disassembly for the 4JH4-HTE.

• Lubrication: Oil-pressure checks, oil and filter changes, oil-cooler cleaning, sump removal, and trochoid-pump inspection.

• Turbocharger: Removal and installation, blower cleaning, turbine-shaft inspection, component wear limits, and assembly cautions.

• Electrical and fault tracing: Starter troubleshooting, alternator service data, instrument-panel wiring diagrams, warning-device checks, and engine symptom charts.

Written for service and repair professionals, including Yanmar authorized distributors and dealers.

Internal Engine Inspection and Assembly

Dimensional tolerance tables cover cylinder blocks, pistons, rings, connecting rods, crankshafts and bearings. Torque charts identify cylinder-head, connecting-rod and flywheel fasteners, including staged cylinder-head tightening.

Separate drawings distinguish the two-valve heads from the four-valve heads on the 4JH4-TE and 4JH4-HTE. On four-valve heads, removing the rocker-arm cover with its pipe seals attached damages those seals.

Inboard, sail-drive and bobtail outline drawings and engine piping diagrams distinguish installation configurations. Marine-gear and sail-drive references do not provide full internal drive-overhaul procedures.

Injection-Pump Variants and Service Limits

The fuel chapter distinguishes the 3JH4E’s TM02 pump, the 4JH4AE’s MP2 system and Bosch VE pumps on the turbocharged engines. A Fuel Flow Diagram and pump/governor sectional views explain the circuits and components.

Dedicated 4JH4AE procedures cover injector spray-pattern and opening-pressure tests, shim adjustment and dial-indicator timing checks. Listed tools include the M14 plunger adapter, P/N 158090-51831.

Internal MP2 pump service is referred to an authorized Yanmar FIE repair facility; VE pump disassembly and adjustment call for a Bosch service shop. The manual also warns that separating the injection-pump drive gear from its hub disturbs the factory timing.

Cooling, Lubrication and Turbocharger Service

The Cooling Flow Diagram separates freshwater and seawater circuits, while the Engine Oil Flow drawing traces the regulating valve, cooler, filter and main gallery.

Seawater-pump coverage includes impeller, wear-plate, seal and bearing inspection. The closed-circuit coolant pump and a damaged engine oil pump are treated as replacement assemblies.

For the IHI RHB52W turbocharger, sectional views and service data distinguish axial and radial shaft checks and show seal and retaining-ring orientation.

Instrument Panels, Starter and Alternator

Model-specific B-Type and C-Type Instrument Panel wiring diagrams identify harness connections, wire-color codes and optional circuits. Alternator diagrams and output curves distinguish standard and optional equipment, including the 4JH4AE dual-alternator arrangement.

Warning-device sections explain oil-pressure and coolant-temperature alarms, sending units, the intake-air heater and engine-stop solenoid. Starter and alternator procedures cover diagnosis and removal/installation; full internal overhaul procedures are not included.

Using Symptoms and Measurements Together

The service standards let a technician compare measured wear with factory limits during inspection. Troubleshooting charts connect starting faults, smoke, vibration, knock, low power, temperature problems and oil-pressure complaints to checks and referenced repair sections.

Compression comparisons help narrow suspected leakage to valves, rings or cylinders before choosing the next inspection.

Disconnect the negative battery cable before service, provide ventilation against carbon monoxide buildup, and never check high-pressure fuel leaks with bare hands.

Valve-Clearance and Turbocharger End-Play Examples

For intake and exhaust valve adjustment, the manual specifies 0.15–0.25 mm with the engine cool. The adjustment sections distinguish conventional rocker arms from the valve-bridge arrangement on the turbocharged models.

For the 4JH4-TE and 4JH4-HTE turbochargers, turbine-shaft end play is specified at 0.03–0.06 mm, with a wear limit of 0.09 mm. These are axial-play figures, separate from the radial-play checks.