Part of the Yanmar Repair Manuals.
Feeler gauge in hand at the rocker cover of a 3TNA72L, you want Yanmar's own clearance in front of you, not a forum guess. This service manual puts the factory servicing standards for the C20R crawler carrier and its 3TNA72L-UFW diesel into 34 tightly packed pages: engine, power train equipment, undercarriage, control devices, hydraulic cylinder, work implement, and a full torque specification table.
Guessing on a machine this age gets expensive fast. Set a clutch by feel and you can glaze it in a week; run a worn rubber track past its limit and you buy a derailment in soft ground. The manual gives the wear limits, clearances, adjustment values and tightening torques that separate a repair from a repeat teardown.
It is a 1.64 MB PDF with 35 bookmarks, so it opens on a phone in the shed and prints page by page for the bench. Wherever the C20R is parked, the numbers travel with it.
What's Inside This Yanmar C20R Manual
| System | Pages | Key Topics |
|---|---|---|
| 1-34 | Engine, Power Train Equipment, Undercarriage, Control Devices, Hydraulic Cylinder, Work Implement, Torque Specifications |
Quick Reference Specifications
| Specification | Value | Page |
|---|---|---|
| C20R | ||
| Engine base fixing bolt tightening torque | 4.5~6.0 kgf·m | p. 31 |
| Battery type | 46B24L-MF | p. 8 |
| Battery voltage - 5 hrs rate capacity | 12-36 V-Ah | p. 8 |
| Battery tightening nut (Under) torque | 0.2~0.4 kgf·m | p. 31 |
| Battery tightening nut (Over) torque | 0.8~1.2 kgf·m | p. 31 |
| Starter motor nominal output | 12-1.0 V-kW | p. 8 |
| Starter motor engagement | Magnetic shift | p. 8 |
| FO filter type | Paper type element | p. 7 |
| Hydraulic oil type (also used as transmission oil) | Yanmar super royal oil SAE 10W-30 Diesel engine oil SAE 10W-30 API CD class | p. 14 |
| Idler Fixing Nut Tightening Torque | 35.0~45.0 kgf·m | p. 31 |
| 3TNA72L series | ||
| Intake Valve Clearance (Cold eng.) | 0.15~0.25 mm | p. 21 |
Yanmar C20R Common Problems This Manual Covers
Engine cranks slowly or will not start
Weak batteries, corroded terminals and tired starter solenoids are the usual suspects on these carriers. The Engine servicing standards list the battery type and capacity plus the starter output, so you can test against real values instead of swapping parts on a hunch.
Manual Section: EngineClutch slip and grabby steering
Steering clutches and brake bands wear, and oil contamination after a leak makes braking and drive behavior erratic. The Power Train Equipment section gives the wear limits and standards you need to decide between adjustment and replacement.
Manual Section: Power Train EquipmentRubber tracks stretch, wear and derail
Worn lugs and a slack track throw easily in soft or side-sloped ground. The Undercarriage section covers rubber track wear limits and idler service so the track stays where it belongs.
Manual Section: UndercarriageTravel levers sloppy or unresponsive
Linkage wear and misadjustment show up as vague levers and a carrier that will not hold a straight line. The Control Devices section sets out the servicing standards for the controls so you can bring the feel back to spec.
Manual Section: Control DevicesDump cylinder drifts or leaks
A bed that creeps down under load points to worn seals or internal bypass in the cylinder. The Hydraulic Cylinder section carries the servicing standards you need to judge whether a reseal will save it or the cylinder is done.
Manual Section: Hydraulic CylinderDump bed pivots worn loose
Slop in the bed pivots and mounts shows up as banging and uneven dumping on rough ground. The Work Implement section gives the servicing standards for the bed and its hardware.
Manual Section: Work ImplementFasteners loosen after field repairs
Reassembling by feel is how engine mounts work loose and battery clamps crack. The Torque Specifications section lists tightening torques fastener by fastener, from the engine base fixing bolts to the idler fixing nut, with thread locker noted where Yanmar calls for it.
Manual Section: Torque SpecificationsFrequently Asked Questions
Which machine and engine does this manual cover?
It is the Yanmar service manual for the C20R crawler carrier with the 3TNA72L-UFW diesel. All 34 pages are servicing standards: Engine, Power Train Equipment, Undercarriage, Control Devices, Hydraulic Cylinder, Work Implement and Torque Specifications.
What is the valve clearance for the 3TNA72L engine?
Intake and exhaust valve clearance is 0.15 to 0.25 mm, set with the engine cold. The figure sits in the Engine servicing standards alongside the other values you need before the rocker cover goes back on. p. 21
Does the manual include torque specifications?
Yes. The Torque Specifications section lists tightening torques by fastener, including 4.5 to 6.0 kgf·m for the engine base fixing bolts and 35.0 to 45.0 kgf·m for the idler fixing nut, with thread locker called out where Yanmar requires it. p. 31
What oil does the C20R use for the transmission and hydraulics?
One oil serves both systems: Yanmar super royal oil SAE 10W-30, or a diesel engine oil SAE 10W-30 of API CD class. The manual lists it as transmission oil, also used as hydraulic oil. p. 14
What do I get after purchasing this Yanmar C20R manual?
You get a 34-page searchable PDF that downloads instantly after checkout. Open it on your laptop, tablet, or phone, and bring it right to the shop floor.
Am I able to print pages from this manual?
Absolutely. No DRM or copy protection. Print the whole manual or just the pages you need. Any home or office printer works.
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