Part of the Yanmar Repair Manuals.
When a ViO20 starts losing revs the moment the boom cylinder loads up, the crew stands still while you guess between fuel, hydraulics, and adjustment. This Yanmar ViO20 service manual takes the guessing out: 436 pages of factory procedures for the 3TNE74-ENBV diesel, the hydraulic system, and the undercarriage of this mini excavator.
The Service Standards section pins down wear limits for rubber and steel crawlers, track rollers, and hydraulic cylinders, plus a full tightening torque list for the machine and engine. The Engine section walks through compression measurement, valve clearance adjustment, fuel injection timing, and cooling system checks, with the specifications to judge what you measure.
It is an English-language PDF (34.46 MB) delivered as an instant download, so you can print the pages you need at the bench and get the machine back on the dirt instead of waiting on a dealer appointment.
What's Inside This Yanmar ViO20 Manual
| System | Pages | Key Topics |
|---|---|---|
| General Cautions for Maintenance Work | 7-18 | Hydraulic Equipment Handling, Hydraulic Piping, Seal Handling, Hydraulic Hose Installation, Hydraulic Hose Specifications |
| Technical Data | 19-31 | Specifications, Outline Drawing, Working Area, Weight List, Lifting Capacity |
| Service Standards | 32-51 | Machine Performance, Engine, Undercarriage, Rubber Crawler, Steel Crawler, Controls, Hydraulic Cylinders, Tightening Torque |
| Engine | 52-94 | Compression Pressure, Valve Clearance, V-Belt, Fuel Injection Valve, Fuel Injection Timing, Cylinder Head, Piston, Crankshaft, Starter Motor, Alternator |
| Hydraulic System | 95-132 | Control Valve Operation, Hydraulic Circuit Schematic, Circuit Operation, Boom, Arm, Bucket, Swing, Travel, Pressure Adjustment, Relief Valves |
| Hydraulic Equipment | 133-311 | Hydraulic Pump, Control Valve, Pilot Valve, Swing Motor, Travel Motor, Pilot Check Valve |
| Adjustment and Repair | 312-388 | Electrical Equipment, Wiring Diagram, Engine Removal, Starter Motor, Undercarriage, Idler, Track Roller, Control Train, Swing Bearing, Hydraulic Cylinders, Swivel Joint, Piping |
| Periodic Inspection and Servicing | 389-391 | Periodic Inspection Schedule, Servicing Intervals |
| Fuel, Lube Oil and Grease | 392-393 | Recommended Fuel, Lubricants, Grease |
| Troubleshooting | 394-433 | Non-Breakdown Phenomena, Machine and Engine Faults, Electrical Equipment on Panel |
| Reference Data | 434-436 | Attachment Specifications |
Quick Reference Specifications
| Specification | Value | Page |
|---|---|---|
| Track roller tightening nut torque | 57.9 to 72.3 ft·lbf (78.4 to 98.0 N·m) | p. 48 |
| Pipe joint bolt (M12) tightening torque | 18.1 to 25.3 ft·lbf (24.5 to 34.3 N·m) | p. 51 |
| Swing motor to Turning frame tightening torque | 57.9 to 72.3 ft·lbf (78.4 to 98.0 N·m) | p. 49 |
| Travel reduction gear oil type | SAE 90 (GL-4) | p. 393 |
| Travel reduction gear oil capacity | 0.53 Qts. (0.5 L) | p. 393 |
| Hydraulic hose working pressure (SAE J517, 100R1, 02 dia.) | 2489 (17.2) PSI (MPa) | p. 14 |
| Hydraulic pipe joint bolt (M12) tightening torque | 18.1 to 25.3 ft·lbf (24.5 to 34.3 N·m) | p. 51 |
| Fuel-water separator element type | Mesh filter | p. 25 |
| LO filter filtration area | 124.1 (800) sq.in. (sq.cm) | p. 25 |
| LO filter valve opening pressure | 11.4 to 17.1 (0.08 to 0.12) PSI (MPa) | p. 25 |
| Air cleaner filtration area | 9.7 (0.9) sq.ft. (sq.m) | p. 25 |
| Rubber crawler lug height wear limit | 0.39 (10) in. (mm) | p. 41 |
Yanmar ViO20 Common Problems This Manual Covers
Engine bogs down under hydraulic load
ViO20 owners report revs dropping or the engine stalling when a hydraulic function is worked hard. The Engine section gives the checks that isolate it: compression measurement, fuel injection valve and timing checks, and maximum and minimum idle speed adjustment.
Manual Section: Engine p. 52Rubber track wear and tension loss
Loose or chunked rubber crawlers chew up idlers and rollers on a machine that tracks between piles all day. Service Standards lists the undercarriage wear limits, including the 0.39 in. (10 mm) lug height limit for rubber crawlers, so you replace on measurement instead of guesswork.
Manual Section: Service Standards p. 32Hydraulic hose and fitting leaks
A weeping fitting turns into a puddle under the machine and a slow, spongy cylinder. The manual's cautions for hydraulic equipment cover correct hose installation, seal handling, and air release of the hydraulic system after the repair, so the fix holds.
Manual Section: General Cautions for Maintenance Work p. 7Overheating and coolant loss
Coolant that disappears without an obvious puddle usually means a seeping hose or radiator. The Engine section includes a procedure for checking the cooling water system and radiator for leakage before the temperature gauge shuts the day down.
Manual Section: Engine p. 52Boom and arm cylinder drift
A bucket that settles on its own mid-lift points to worn seals or internal leakage in a cylinder. The Hydraulic Cylinders service standards give the figures to check the cylinders against before you commit to a reseal.
Manual Section: Hydraulic CylindersLoose undercarriage and swing motor bolts
Track roller nuts and swing motor mounting bolts work loose with vibration, and running them loose damages the mounting faces. The tightening torque list specifies 57.9 to 72.3 ft-lbf for both, with thread locker called out for reassembly.
Manual Section: Service Standards p. 32Frequently Asked Questions
Which machine does this manual cover?
It covers the Yanmar ViO20 mini excavator with the 3TNE74-ENBV diesel engine (Yanmar publication 220104). Machine specifications, outline drawings, working area, weights of main parts, and lifting capacities are all included.
Does it include tightening torque specs?
Yes. The Service Standards section carries a tightening torque list for the machine and engine, including 57.9 to 72.3 ft-lbf for track roller nuts and swing motor mounting bolts, 18.1 to 25.3 ft-lbf for M12 hydraulic pipe joint bolts, and torques for general bolts and nuts. p. 32
Are engine adjustment procedures covered?
Yes. The Engine section covers compression measurement, valve clearance adjustment (0.0079 in. / 0.2 mm intake and exhaust on a cold engine), V-belt tension, fuel injection valve and timing checks, idle speed adjustment, and cooling system leak checks. p. 52
Does it list fluid capacities and oil types?
Yes. The Technical Data section lists machine specifications including the 9.24 gal (35 L) hydraulic oil tank, and the manual specifies SAE 90 (GL-4) gear oil at 0.53 qt (0.5 L) per side for the travel reduction gears. p. 19
What format is this manual in?
A 436-page Service Manual in searchable PDF format, available the moment you complete checkout. View on computer, tablet, or phone, with no shipping wait.
Are there any print restrictions on this manual?
No restrictions at all. Print individual pages, full chapters, or the entire manual. The PDF is completely unlocked.
Can I find hydraulic circuit diagrams in this Yanmar ViO20 manual?
Full hydraulic system diagrams are included, covering circuits, valve locations, and hydraulic component specs for the Yanmar ViO20.
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