Rebuilding an S4K or S6K turbodiesel back to factory spec in your 10-ton excavator means working from real numbers, not forum threads. This 148-page manual (OEM #99499-10190) carries step-by-step procedures for cylinder head disassembly, camshaft, pistons, connecting rods, and fuel injection nozzle teardown, plus wiring diagrams and electrical system schematics. Exploded views back up the valve clearance specs, the full tightening torque table, and a maintenance chart laid out by 50-, 250-, 500-, and 1000-hour intervals. Set injection nozzle opening pressure to 21.6 MPa; torque the head bolts to 118±5 N·m. Every section is bookmarked and the text is keyword-searchable, so one download pulls up on any device on the shop floor.
What's Inside This Mitsubishi S4K, S6K Manual
| System | Pages | Key Topics |
|---|---|---|
| Main Page | 1-4 | Introduction, How to Use This Manual, Fuel Injection Pump, Governor, And Turbocharger Coverage, Manual Sections and Contents in Index, References for Operation, Parts |
| - General Information | 5-12 | General (S4K-T Diesel Engine - External Views, S6K-T Diesel Engine - External Views, Engine Serial Number Location, Engine Model and Application Codes), Specifications |
| - Maintenance Standards | 13-23 | Maintenance Standards, Important Bolts and Nuts, Standard Bolts, Standard Stud Bolts, Standard Plugs, Sealants |
| - Special Tools | 24-27 | - |
| - General Instructions | 28-30 | S4K-T Diesel Engine - External Views, S6K-T Diesel Engine - External Views, Engine Serial Number Location, Engine Model and Application Codes |
| - Testing and Adjusting | 31-42 | Adjustments (Valve Clearance Inspection and Adjustment, Fuel System Priming, Fuel Injection Timing Inspection and Adjustment, No-Load Minimum Speed and Maximum Speed Setting Inspection and Adjustment, Fan Drive Belt Inspection and Adjustment) |
| - Engine Accessory Removal and Installation | 43-49 | Preparatory Steps, Engine Accessory Removal, Engine Accessory Installation |
| - Engine Proper | 50-95 | Cylinder Heads and Valve Mechanism (Disassembly, Repair, Reassembly), Flywheel, Timing Gears and Camshaft (Disassembly, Pistons, Connecting Rods |
| - Air Inlet and Exhaust System | 96-98 | Paper-Element Type Air Cleaner (Disassembly and Inspection), Exhaust Manifold (Inspection) |
| - Lubrication System | 99-107 | Oil Pump (Disassembly, Repair, Reassembly), Oil Filter (Disassembly and Inspection), Pressure Relief Valve (Inspection), Relief Valve (Inspection) |
| - Cooling System | 108-114 | Water Pump (Disassembly, Inspection, Reassembly), Thermostat (Inspection), Radiator, Fan and Fan Belt (Inspection) |
| - Fuel System | 115-119 | Fuel Filter (Disassembly and Inspection), Fuel Injection Nozzles (Disassembly, Repair, Reassembly) |
| - Electrical System | 120-133 | Starter (Disassembly, Repair, Reassembly), Alternator (Disassembly, Inspection, Heater Relay (Inspection), Air Heater (Inspection) |
| - Workshop Theory | 134-137 | Heater Relay, Air Heater |
| -Maintenance Chart | 138-148 | Every 50 Service Hours, Every 250 Service Hours, Every 500 Service Hours, Every 1000 Service Hours, Every 2 Years, As Required |
Quick Reference Specifications
| Specification | Value | Page |
|---|---|---|
| All Models | ||
| Cylinder head bolts tightening torque | 12±0.5 kgf·m (87±3.6 lbf·ft) [118±5 N·m] | p. 21 |
| Fuel filter replacement interval | every 500 hours | p. 116 |
| Fuel filter element tightening torque | 39±5 N·m (4±0.5 kgf·m) | p. 117 |
| Fuel injection nozzle valve opening pressure (Nominal Value) | 220 (3128) [21.6] kgf/cm² (psi) [MPa] | p. 15 |
| Fuel injection nozzle spray angle | 155° | p. 15 |
| Air cleaner element replacement interval | every 1000 hours | p. 97 |
| Air cleaner clamp tightening torque | 0.5±0.1 kgf·m (3.6±0.7 lbf·ft) [4.9±1.0 N·m] | p. 97 |
| Thermostat valve opening temperature | 71±2 (159.8±3.6) °C (°F) | p. 15 |
| Thermostat temperature at which valve lifts more than 10 mm (0.4 in.) | 85°C (185°F) | p. 15 |
| Fan drive belt tension (deflection) | 12 (0.473) mm (in.), approx. | p. 14 |
| S4K | ||
| Water pump delivery capacity at 1800 rpm | 130 (34.3) liter (U.S. gal)/min | p. 15 |
| S4K-T | ||
| Water pump delivery capacity at 1800 rpm | 145 (38.3) liter (U.S. gal)/min | p. 15 |
Mitsubishi S4K, S6K Common Problems This Manual Covers
Mitsubishi S4K S6K diesel hard to start, white smoke at idle, power loss p. 115
Check the fuel filter first and swap it once service hours pass 500 (page 116). Bleed the lines to clear trapped air using the priming steps on page 31. Injection nozzle opening pressure should read 220 kgf/cm² (21.6 MPa); if it falls short, pull and inspect the nozzles per page 115.
Manual Section: - Fuel SystemEngine cranks slowly or won't fire at all in cold weather, no start p. 120
Inspect the air heater and heater relay on page 120. Read compression on each cylinder against the 30 kgf/cm² (2.9 MPa) assembly standard from page 30, and confirm the battery is charged with tight connections. Low compression will keep a cold engine from firing no matter how good the heater is.
Manual Section: - Electrical SystemConstant coolant top-offs required, temperature gauge climbing steadily during heavy load operation p. 108
Confirm coolant level: the S4K holds 6 L (1.6 U.S. gal.) and the S6K holds 9 L (2.4 U.S. gal.) per page 9. Test the thermostat, which should begin opening at 71 ± 2 °C (page 10). Check the fan belt for roughly 12 mm deflection (page 14), and if temperatures stay high, disassemble the water pump per page 108.
Manual Section: - Cooling SystemLow oil pressure warning comes on during operation, knocking noise from engine p. 99
Verify the oil level is full and replace the oil filter past 250 service hours per page 104, torquing the new element to 39 ± 5 N·m (page 105). Pull the oil pump and relief valve for inspection per page 99. If knocking continues, measure bearing clearances against the maintenance standards on page 13.
Manual Section: - Lubrication SystemExcessive blowby from breather tube with high oil consumption between oil changes p. 50
Measure compression on all cylinders; standard assembly pressure is 30 kgf/cm² (2.9 MPa) per page 30. Low readings on multiple cylinders point to worn rings or bores. Remove the cylinder head per page 50 and inspect piston rings, cylinder bores, and valve seals for wear before committing to a full overhaul.
Manual Section: - Engine ProperFuel system loses prime after sitting overnight, requires excessive cranking to start p. 31
Bleed the fuel system per page 31, then check the filter housing for cracks or loose fittings (page 115). Losing prime overnight usually traces to a failed filter seal, a cracked line, or a leaking injector return. Replace the filter every 500 hours and torque the new element to 39 ± 5 N·m per page 117.
Manual Section: - Testing and AdjustingFrequently Asked Questions
What are the torque specs for Mitsubishi S4K/S6K cylinder head bolts?
Mitsubishi S4K/S6K cylinder head bolts torque to 12±0.5 kgf·m (87±3.6 lbf·ft), or 118±5 N·m. Apply it in two or three steps, following the sequence shown in the manual.
What are the torque specs for Mitsubishi S4K/S6K main bearing caps?
Main bearing cap bolts on the S4K/S6K are listed at 14±2 kgf·m (102±14.5 lbf·ft), or 137±19 N·m, in the important bolts and nuts table. To install, oil the bolts and tighten to 13.5 – 14.5 kgf·m (97.6 – 105 lbf·ft), or 132 – 142 N·m.
What are the replacement specifications for fuel filters?
Replace the S4K/S6K fuel filter every 500 service hours. As you swap it out, inspect the filter element closely for any clogging or tears before fitting the new one.
What do I get after purchasing this Mitsubishi S4K, S6K manual?
Immediate download of the complete 148-page searchable Service Manual. Open it on any device, from the laptop at your desk to a phone in the field.
Is this Mitsubishi S4K, S6K Service Manual printable?
Yes. The PDF carries no DRM restrictions, so you can print any page or section you need on any standard shop printer.
Can I find hydraulic circuit diagrams in this Mitsubishi S4K, S6K manual?
No, this Mitsubishi S4K, S6K Service Manual focuses on the engine base and does not include hydraulic system diagrams for the excavator.
Document Quality
This document is a scanned PDF of a physical service manual. The text is image-only, so you will not be able to search or copy text directly from the document. Text quality is generally clear and readable, though it has the characteristic appearance of scanned material rather than crisp, native digital text. All diagrams and illustrations are raster images, but they are clear, and their labels are readable. Page condition is mostly clean, with some pages showing slight skew, faint background discoloration, or minor specks typical of scanned documents, but there are no entirely blank pages.
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