All 392 pages of this Yanmar JH4 Series Service Manual (OEM #0BJH4-G00102) zero in on one job: putting your 3JH4E, 4JH4AE, 4JH4-TE, or 4JH4-HTE marine diesel back to factory spec. If you've been hunting for a Yanmar 4JH4-TE service manual PDF that covers the full machine, this is it: electrical wiring diagrams, fuel flow schematics, cooling circuit diagrams, and a dense bank of step-by-step procedures spanning every system from turbocharger to raw-water cooling. The troubleshooting chapter walks you through a structured fault chart plus compression diagnostics; flip to the engine section for a special torque chart, standard fastener values, and a complete service standards appendix. Set cylinder head bolts to 85.2-91.2 N·m; on the -TE and -HTE, the injection pump drive gear nut gets 59-69 N·m. Every hour at the dock costs money. Bookmark-navigable and keyword-searchable; open it on your tablet and get to work.
What's Inside This Yanmar 3JH4E, 4JH4AE, 4JH4-TE, 4JH4-HTE Manual
| System | Pages | Key Topics |
|---|---|---|
| Introduction | 5-6 | Revision History |
| Safety | 7-16 | Safety Statements, Safety Precautions, Location of Safety Labels |
| General Service Information | 17-74 | Safety Precautions, Engine Outline Drawings, Engine Piping Diagrams, Location of Nameplates, Diesel Fuel, Engine Oil, Engine Coolant, Principal Engine Specifications |
| Periodic Maintenance | 75-84 | Epa Requirements, Periodic Maintenance Schedule, Periodic Maintenance Procedures |
| Engine | 85-198 | Safety Precautions, Specifications, Special Torque Chart, Standard Torque Chart (Without Lubricating Oil), Special Service Tools, Measuring Instruments, Sealants and Compounds |
| Fuel System | 199-264 | Safety Precautions, Specifications, Special Service Tools, Fuel System Components, Fuel Flow Diagram, Fuel System Tests, Fuel System Service |
| Cooling System | 265-296 | Safety Precautions, Specifications, Special Service Tools, Measuring Instruments, Cooling Flow Diagram, Tests and Adjustments, Drain and Refill Seawater Cooling System |
| Lubrication | 297-310 | Safety Precautions, Specifications, Special Service Tools, Tests and Adjustments, Repair |
| Turbocharger | 311-322 | Safety Precautions, Specifications, Turbocharger Components, Special Service Tools, Washing the Turbocharger Blower, Clean Air Cleaner |
| Starter Motor | 323-328 | Safety Precautions, Starter Motor Specifications, Starter Motor Troubleshooting, Starter Motor Service |
| Alternator | 329-338 | Safety Precautions, Specifications, Alternator Service |
| Electrical | 339-364 | Safety Precautions, Component Locations, Wiring Diagram, Instrument Panel, Function Description - Warning Devices |
| Troubleshooting | 365-376 | Safety Precautions, Troubleshooting Chart, Troubleshooting by Measuring Compression Pressure, After Troubleshooting or Repair |
| Service Standards | 377-392 | Engine Tuning, Engine Body, Lubricating Oil System (Trochoid Pump), Main Bolt and Nut, Standard Bolts and Nuts (Without Lubricating Oil) |
Quick Reference Specifications
| Specification | Value | Page |
|---|---|---|
| All Models | ||
| Oil Pressure Alarm Trigger Threshold | below 0.01-0.03 MPa (0.1-0.3 kgf/cm2, 1.42-4.26 psi) | p. 358 |
| Raw-water Impeller Replacement Criteria | Replace if cracks, broken vanes or excessive wear | p. 286 |
| Lubricating Oil Filter tightening torque | 20 - 24 N·m (177-212 lb-in) | p. 306 |
| Thermostat Opening Temperature | 75-78°C (167-172°F) | p. 273 |
| Thermostat Full Open Temperature | 90°C (194°F) | p. 273 |
| Coolant Recovery Tank Capacity (Full) | 0.8 L | p. 289 |
| 3JH4E, 4JH4AE, 4JH4-TE, 4JH4-HTE | ||
| Cylinder Head Bolt tightening Torque (Final) | 85.2-91.2 N·m (62.9~67.3 lb-ft) | p. 143 |
| 4JH4AE | ||
| Fuel Nozzle Retainer Bolt | 26.4 ± 2.0 N·m (19.5 ± 1.5 lb-ft) | p. 185 |
| Engine Oil Capacity (Total) | 5.0 ± 0.3 L | p. 63 |
| 4JH4-TE, 4JH4-HTE | ||
| Fuel Injection Pump Drive Gear Nut | 59-69 N·m (44-51 lb-ft) | p. 183 |
| Engine Oil Capacity (Total) | 5.7 ± 0.3 L | p. 67 |
| 3JH4E | ||
| Engine Oil Capacity (Total) | 5.0 ± 0.3 L | p. 62 |
Yanmar 3JH4E, 4JH4AE, 4JH4-TE, 4JH4-HTE Common Problems This Manual Covers
Yanmar JH4 series engine overheats under load, coolant temperature climbs above normal range p. 286
Check the seawater strainer first; clear any debris restricting flow. Remove and inspect the raw-water impeller (page 286) for cracked or broken vanes; replace if found. Test the thermostat: it must start opening at 75-78°C (167-172°F) and achieve 8 mm or more lift at 90°C. Refill the coolant recovery tank to 0.8 L (page 289) if low.
Manual Section: Cooling SystemRough running, black smoke, and loss of rated RPM after months of light-load motoring p. 241
If rough running persists, remove and clean the fuel injection nozzles; torque the retainer bolt to 39.2 N·m on reinstall (page 241). Check the troubleshooting chart on page 368 to rule out compression loss as a contributing factor.
Manual Section: Fuel SystemEngine won't start or turns over slowly, fuel filter changes haven't resolved the issue p. 368
Replace the primary fuel filter and bleed the fuel system to clear air from the lines (Fuel System, page 199). Verify battery voltage holds steady under cranking; the 1.4 kW starter (page 326) draws heavy current in cold conditions. If the engine fires but stalls, measure fuel feed pump pressure and inspect injectors for wear.
Manual Section: TroubleshootingOil pressure warning alarm activates at idle, engine shuts down or warning light stays on p. 297
Check oil level first; top up to 5.0 ± 0.3 L (3JH4E/4JH4AE) or 5.7 ± 0.3 L (4JH4-TE/HTE). Seat the oil filter to 20-24 N·m (page 306). The alarm activates below 0.01-0.03 MPa (1.42-4.26 psi); if pressure stays low after refilling, run the oil flow and pressure tests on page 297 to isolate pump or relief-valve failure.
Manual Section: LubricationAbnormal engine knock, scoring, or rapid ring wear during or just after the first 10 hours p. 78
Avoid sustained full-throttle runs for the first 10 hours; vary speed and keep load moderate. Follow the break-in maintenance intervals on page 78. After break-in, check valve clearance: 0.2 ± 0.05 mm on both intake and exhaust. If knocking persists, pull the head and inspect cylinder walls for scoring before continuing operation.
Manual Section: Periodic MaintenanceFrequently Asked Questions
What is the torque spec for the Yanmar JH4 cylinder head bolts?
The cylinder head bolts for 3JH4 and 4JH4 models should be tightened in two steps. First, tighten to 44-54 N·m (32~40 lb-ft), then to 85.2-91.2 N·m (62.9~67.3 lb-ft). It is specified to coat the bolts with lubricating oil before tightening.
What is the torque spec for the Yanmar JH4 valve cover, injector, or fuel pump bolts?
For the Fuel Injector Nozzle Retainer Bolt (M8 x 1.25), the tightening torque is 24.4-28.4 N·m (18.0-21.0 lb-ft) without lubricating oil. The Fuel Injection Pump Gear Nut for 3JH4E is 78-88 N·m (57.5-64.9 lb-ft) without lubricating oil, for 4JH4AE it is 32.3-36.3 N·m (23.8-26.8 lb-ft) without lubricating oil, and for 4JH4-TE/4JH4-HTE it is 59-69 N·m (43.5-50.9 lb-ft) with lubricating oil. The Rocker Arm Shaft Support bolts should be tightened to 24-27 N·m (18-20 lb-ft).
What are the replacement specifications for raw-water impeller?
For the seawater pump impeller, the manual specifies to inspect it for cracks, broken vanes, or excessive wear. If any of these conditions are found, the impeller should be replaced as necessary. No specific numerical replacement specifications are provided.
How do you fix yanmar JH4 series engine overheats under load, coolant temperature climbs above normal range?
Check the seawater strainer first; clear any debris restricting flow. Remove and inspect the raw-water impeller (page 286) for cracked or broken vanes; replace if found. Test the thermostat: it must start opening at 75-78°C (167-172°F) and achieve 8 mm or more lift at 90°C. Refill the coolant recovery tank to 0.8 L (page 289) if low.
How will I receive this Service Manual?
This is a 392-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 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?
Complete wiring diagrams are included, covering all electrical circuits, harness routing, and connector pinouts for the Yanmar 3JH4E & variants.
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