Need the factory operating procedures for your Yanmar marine diesel engine? All 705 pages of this Yanmar 4LHA-STZP operation manual pdf (OEM #49961-205431) break down the complete setup and maintenance for the 4LHA-HTP, 4LHA-HTZP, and 4LHA-DTZP variants. You get complete wiring diagrams, detailed piping schematics, and a full troubleshooting section to keep your vessel running smoothly. Open to the maintenance schedules to find step-by-step guidance for every 50-hour to 2000-hour inspection interval. Verify your 100x110 mm bore and stroke dimensions, and confirm the 13.0L crankcase is topped off with 15W40 oil. Everything you need to operate and maintain a 4LHA-series marine diesel is in one download.
What's Inside This Yanmar 4LHA Series Manual
| System | Pages | Key Topics |
|---|---|---|
| For Safe Operation | 4-8 | Warning Symbols, Safety Precautions, Location of Product Safety Labels |
| Explanation of Product | 9-22 | Engine Specifications, Names of Parts, Major Servicing Parts, Control Panel, Remote Control Handle |
| Before Operation | 23-31 | Fuel Oil, Lube Oil & Cooling Water, Supplying Fuel, Bleeding the Fuel System, Supplying Marine Drive Oil, Supplying Cooling Water |
| How to Operate | 32-41 | Inspection Before Starting, Starting, Adjusting the Engine Speed, Clutch Operation for the Marine Drive, Stopping the Engine, Long-Term Storage |
| Maintenance & Inspection | 42-54 | List of Periodic Inspections, Periodic Inspection Items |
| Trouble and Troubleshooting | 55-56 | Troubleshooting |
| System Diagrams | 57-63 | Piping Diagram, Wiring Diagram |
| Spanish | 69-135 | - |
| Italain | 136-264 | French, German |
| Finnish | 265-388 | Dutch |
| Swedish | 389-512 | Norwegian |
| Danish | 513-574 | - |
| Greek | 575-636 | - |
| Portuguese | 637-698 | - |
| Appendix | 699-705 | - |
Quick Reference Specifications
| Specification | Value | Page |
|---|---|---|
| Engine Lube Oil SAE Viscosity | 15W40 | p. 15 |
| Engine Lube Oil Capacity (All) | 13.0 l | p. 15 |
| Lube Oil Filter Part Number | 127695-35150 | p. 47 |
| Lube Oil Filter Torque | hand tight + 3/4 turn with filter wrench | p. 47 |
| Bore x Stroke | 100x110 mm | p. 13 |
| Displacement | 3.455 L | p. 13 |
| High idling rpm | 3700 ± 25 rpm | p. 13 |
| Low idling rpm | 750 ± 25 rpm | p. 13 |
| Lube oil capacity (All) | 13.0 L | p. 13 |
| Cooling water capacity (Engine) | 15 L | p. 13 |
| Recommended battery capacity | 12V×120Ah | p. 13 |
| V-belt tension (give) | 8~10mm | p. 54 |
Yanmar 4LHA Series Common Problems This Manual Covers
Yanmar 4LHA-STP produces heavy dark smoke and very slow acceleration when throttled up above 1700 rpm.
Inspect the air intake and precleaner. Remove the air filter element and replace it if damaged or excessively dirty. Verify high idling speed reaches 3700 ± 25 rpm without load. If the engine still smokes, check the troubleshooting procedures.
Manual Section: Poor Exhaust Color TroubleshootingStarter clicks repeatedly but does not spin or engine turns over too slowly to fire.
Check the battery condition and connections. Verify you have the recommended 12Vx120Ah battery capacity installed. Inspect the V-belt tension and adjust it to 8~10mm deflection as detailed on page 54. Clean all terminal posts and tighten the main starter cables.
Manual Section: Starting Failures TroubleshootingAlarm buzzer keeps sounding and low oil pressure warning lamp stays illuminated after starting.
Verify the engine lube oil level on the dipstick. Drain the pan and refill with 13.0 L of 15W40 oil as listed on page 15. Install a new 127695-35150 oil filter, tightening it hand tight plus 3/4 turn. Test run and confirm the alarm clears.
Manual Section: Alarm and Warning Devices TroubleshootingPoor combustion and potential bore glazing after continuous operation below the optimal torque band. p. 46
Drain the crankcase and replace the engine oil every 250 Hrs. or 1 yr. as specified on page 46. Refill the system with 13.0 L of approved oil. Verify the low idling rpm sits correctly at 750 ± 25 rpm to prevent poor combustion.
Manual Section: EnglishFrequently Asked Questions
How do I reset the alarm on a YANMAR 4LHA-HTP?
The alarm buzzer stops sounding and all warning lamps go off when the key switch is turned to START to start the engine and then returned to ON after the engine has started. If they do not work normally, contact your dealer.
What do the YANMAR 4LHA error codes mean?
The YANMAR 4LHA engine does not use numerical error codes. Instead, warning lamps on the control panel illuminate when sensors detect an abnormality during engine operation. These lamps indicate specific issues such as charging failure, high cooling water temperature, low lube oil pressure, excessive fuel filter drain, low gear oil level in the stern drive, or abnormal boost pressure.
How do I clear an overheat or low-oil-pressure alarm on a YANMAR 4LHA engine?
To clear an overheat or low-oil-pressure alarm, you should immediately shift to low-speed operation, check which warning lamp is illuminated, and stop the engine for inspection. If no abnormality is found and the engine operates without issues, return to port at the lowest possible speed and request repairs.
What are the torque specs for YANMAR 4LHA head bolts / injector bolts / rocker cover bolts?
The manual provides tightening torque specifications for standard nuts and bolts based on their diameter and pitch. For example, an M10x1.5 bolt requires a tightening torque of 49.0±4.9 N.m (5.0±0.5 Kgf-m). It also specifies that bolts with a "7" mark on the head should use the listed torque, while those without a "7" mark should be tightened to 60% of the listed torque, and aluminum alloy parts to 80%. Specific torque for head bolts, injector bolts, or rocker cover bolts is not explicitly listed by name, but general bolt sizes are provided.
Is this Yanmar 4LHA-HTP & variants Operation Manual a digital download?
A 705-page Operation Manual in searchable PDF format, available the moment you complete checkout. View on computer, tablet, or phone, with no shipping wait.
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 Yanmar 4LHA-HTP & variants Operation Manual have electrical diagrams?
Yes. You'll find an electrical wiring diagram covering the main wiring layout.
Document Quality
This document is a scanned PDF with an OCR layer, so you can search and copy the full text. The text is generally crisp and easy to read, though some edges show slight pixelation typical of scanned documents. Diagrams and illustrations, including the detailed piping and wiring schematics in the appendices, are raster images; their labels are mostly readable, but some very small text may become less sharp at high zoom. The pages are clean, free of significant scan artifacts, stains, or skewed content, and there are no unexpected blank pages.
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