This is the factory Mitsubishi service manual for the 4G33, 4G52, and 4G54 forklift engines, covering the FG10, FGC10, FG14, FG15, FGC15, FG20, FGC20, FG25, FGC25, FG30, and FGC30 trucks. It runs 213 pages of engine repair procedures with a text layer for searching.You get full teardown and rebuild coverage: cylinder head and block service, lubrication, fuel and cooling systems, electrical equipment, plus a troubleshooting section and service data with torque values and clearances. Specifications are broken out per engine, so you can find the right displacement, compression ratio, and output for your 4G33, 4G52, or 4G54.Independent mechanics and owners restoring older Mitsubishi lift trucks can use it to diagnose hard starting, chase down power loss, and carry out top-end work with the exact factory numbers instead of guessing.
What's Inside This Mitsubishi 4G33, 4G52, 4G54 Manual
| System | Pages | Key Topics |
|---|---|---|
| General Information | 4-10 | Engine Models, Performance Curves, Sectional Views, Specifications, Serial Number Location |
| Engine Proper | 11-42 | Cylinder Head Assembly, Removal and Disassembly (4G33 / 4G52 / 4G54), Reassembly and Installation, Cylinder Block Assembly, Crankcase Ventilation |
| Lubrication System | 43-47 | Engine Oil, Oil Filter, Oil Pump (4G33 / 4G52 / 4G54), Oil Pressure Switch |
| Fuel System | 48-57 | Fuel Pump, Construction and Function, Removal and Installation, Performance Test, Carburetor, Air Governor |
| Cooling System | 58-62 | Antifreeze Solution, Water Pump (4G33 / 4G52 / 4G54), Thermostat |
| Electrical Equipment | 63-81 | Starting Motor (Dry Clutch / Front Wet Clutch), Distributor, Ignition Coil, Spark Plugs, Alternator, Regulator, Battery |
| Special Service Tools | 82-85 | Engine, Lubrication System, Cooling System |
| Service Data | 86-101 | Maintenance Schedule, Maintenance Standards, Tightening Torque, Important Bolts and Nuts, General Bolts, Tapered Threads, Recommended Sealants |
| Troubleshooting | 102-114 | General Troubleshooting, Engine Proper Troubleshooting, Carburetor Troubleshooting, Electrical Equipment Troubleshooting |
| Appendix, Inspection Guide (Part 1) | 115-140 | Basic Mechanical Troubles, Troubleshooting and Analysis |
| Appendix, Inspection Guide (Part 2) | 141-213 | Cylinder Head and Valve Mechanism, Cylinder Sleeves, Pistons and Connecting Rods, Flywheel and Timing Gears, Crankcase and Major Running Parts, Lubrication System, Cooling System, Fuel System, Electrical System, Overhaul Guide |
Quick Reference Specifications
| Specification | Value | Page |
|---|---|---|
| 4G52, 4G54 | ||
| Cylinder head bolts torque (cold) | 9 ~ 10 kg-m (65 ~ 72 lb-ft) | p. 100 |
| Cylinder head bolts torque (hot) | 10 ~ 11 kg-m (72 ~ 80 lb-ft) | p. 100 |
| Distributor point gap | 0.45 ~ 0.55 mm (0.0177 ~ 0.0217 in.) | p. 74 |
| All Models | ||
| Rocker cover bolts torque | 0.5 ~ 0.7 kg-m (3.6 ~ 5.1 lb-ft) | p. 100 |
| Spark plugs torque | 2 ~ 3 kg-m (15 ~ 22 lb-ft) | p. 100 |
| Gasketed surface warpage (max) | 0.05 mm (0.0020 in.) | p. 90 |
| Intake and exhaust manifold attaching bolts torque | 1.5 ~ 2 kg-m (10.8 ~ 14 lb-ft) | p. 100 |
| 4G33 | ||
| Cylinder head bolts torque (cold) | 7 ~ 8 kg-m (51 ~ 58 lb-ft) | p. 100 |
| Cylinder head bolts torque (hot) | 8 ~ 9 kg-m (58 ~ 65 lb-ft) | p. 100 |
| Distributor point gap | 0.5 ± 0.05 mm (0.020 ± 0.0020 in.) | p. 74 |
| 4G33-32FD | ||
| Engine Displacement (Nominal) | 1450 cc | p. 6 |
| 4G52-33FD | ||
| Engine Displacement (Nominal) | 2000 cc | p. 6 |
Mitsubishi 4G33, 4G52, 4G54 Common Problems This Manual Covers
Hard starting or no-start
Aging distributors, worn ignition wires, and fouled spark plugs leave these forklift engines cranking without firing. The electrical section walks through the ignition and starting components so you can isolate the fault.
Manual Section: Electrical Equipment p. 63Power loss and misfire under load
A tired carburetor or clogged fuel filter shows up as poor acceleration and stumbling when the truck is working. Fuel system checks and adjustments help you trace it back to delivery or mixture faults.
Manual Section: Fuel System p. 48Overheating and coolant loss
Neglected cooling systems and a failing water pump push these engines to overheat, sometimes leading to head damage on the 4G52. The cooling section covers inspection and service to catch it early.
Manual Section: Cooling System p. 58Low compression and blue smoke
High-hour engines lose compression through worn rings and valve guides, burning oil and smoking under load. The engine proper section covers cylinder head and block teardown, inspection, and reassembly.
Manual Section: Engine Proper p. 11Low oil pressure or oil leaks
Worn oil pumps, tired seals, and a clogged filter drop pressure and let oil seep past aging gaskets. The lubrication section covers the oil pump, filter, and pressure switch for the 4G33, 4G52, and 4G54.
Manual Section: Lubrication System p. 43Intermittent faults hard to pin down
Older forklift engines throw mixed symptoms that cross ignition, fuel, and mechanical wear. The troubleshooting section gives a structured path to narrow the diagnosis before you start pulling parts.
Manual Section: Troubleshooting p. 102Frequently Asked Questions
Which engines and forklift models does this manual cover?
It covers the Mitsubishi 4G33, 4G52, and 4G54 engines fitted to FG10, FGC10, FG14, FG15, FGC15, FG20, FGC20, FG25, FGC25, FG30, and FGC30 lift trucks, with separate procedures and specs for each engine.
What are the cylinder head bolt torque specs?
The service data lists cylinder head bolt torque (cold) at 7 to 7.5 kg-m for the 4G33 and 9 to 10 kg-m for the 4G52 and 4G54, alongside connecting rod cap and other fastener values. p. 86
Does it explain how to set the ignition timing?
Yes. The electrical equipment section covers the distributor and ignition system, which is where you set timing and diagnose the hard-starting and no-start faults common on these older engines. p. 63
How often should the engine oil be changed?
The manual specifies an engine oil change every 200 hours for all three engines. The lubrication section covers the oil, filter, and pump service that goes with that interval. p. 43
What do I get after purchasing this Mitsubishi 4G33, 4G52, 4G54 manual?
A 213-page Service Manual in searchable PDF, ready to download the moment checkout completes. Open it on a computer, tablet, or phone, with no shipping wait.
Can I print this manual?
No restrictions at all. Print individual pages, full chapters, or the entire manual. The PDF is completely unlocked.
Are there wiring harness diagrams in this Mitsubishi 4G33, 4G52, 4G54 manual?
Included. The Mitsubishi 4G33, 4G52, 4G54 Service Manual covers complete wiring harness diagrams, electrical circuits, and connector pinouts.
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