Description

Komatsu PC27MR-2, PC30MR-2, PC35MR-2, PC50MR-2, PC40MR-2 2006 Workshop Manual

If you have ever spent a Saturday chasing a hydraulic leak on a mini excavator because an aftermarket manual printed the wrong pilot pressure spec, you know exactly why I will not touch anything but factory documentation. This Komatsu PC27MR-2, PC30MR-2, PC35MR-2, PC50MR-2, PC40MR-2 2006 Workshop Manual is 621 pages of OEM data—no reprints, no third-party edits, no guesswork.

You do not buy a manual like this for the cover photo. You buy it because Section 01 gives you the actual fuel and coolant specifications for the 3D82AE-5M and 4D88E-5X engines, and because Section 20 tells you exactly how to measure compression pressure, adjust valve clearance, and set injection timing without tearing something loose. I have rebuilt more hydraulic pumps than I care to count, and the difference between a factory torque value and a generic one is the difference between a seal that holds and a seal that leaks at 2,500 hours.

Specifications and Lubricants: Section 01

Section 01 starts with dimension drawings and working range diagrams—useful when you are fabricating a mount or checking if a used machine still fits your trailer. The weight table and lubricant, fuel, and coolant specifications are right there. For the PC27MR-2 (serial 15001 and up) through the PC50MR-2 (5001 and up), you get the exact oil grades and capacities. No need to call the dealer and wait on hold. The manual lists the engines: PC27MR-2 uses the 3D82AE-5M; PC30MR-2 uses the 3D84E-5N; PC35MR-2 uses the S3D84E-5PBA or 3D88E-5P; PC40MR-2 and PC50MR-2 use the 4D88E-5X. If you need the companion engine manual, see the 68E-88E Series Engine Shop manual referenced on page 00-1.

Testing and Adjusting: Valve Clearance and Fuel Timing

Section 20 is where the manual earns its keep on the bench. It opens with standard value tables for engine and chassis parts. Then it walks through each test: measuring engine speed, exhaust gas color, adjusting valve clearance, measuring compression pressure, testing and adjusting fuel injection timing. I have watched too many guys guess at the alternator belt tension and burn up a bearing—this section gives you the procedure and the tool list. You also get the LS differential pressure test and the PC valve adjustment for the hydraulic system. Page 20-1 starts the full list, but the torque specs for the cylinder head and other fasteners are scattered through the procedures—do not skip back to Section 10 if you need the cooling system or cylinder standards.

Troubleshooting H-Mode: When the Hydraulics Go Wrong

The troubleshooting section is split into E-mode (electrical) and H-mode (hydraulic/mechanical). H-mode covers 12 specific fault conditions: low power, engine stall, abnormal pump noise, poor fine control, low boom or arm speed, excessive drift, large time lag, and more. Each fault has a table with probable causes and inspection steps. For example, H-1 (speed or power low across all functions) directs you to check the hydraulic pump, control valve, and LS circuit. The manual also includes the connector arrangement diagram and T-adapter box tables—essential when you are chasing an electrical gremlin in the monitor system. Do not try to diagnose a swing brake release pressure issue without this manual; the spec is buried in the standard value tables and you will not find it in a Chilton book.

3 Reasons OEM Documentation Wins Over Aftermarket

First, the torque specs. Aftermarket manuals often list generic values that do not account for the specific bolt grade or thread lubricant. Komatsu prints the exact values used on the assembly line. Second, the wiring diagrams and connector pinouts are model-specific—the PC40MR-2 has different sensors than the PC27MR-2, and this manual gives you both. Third, the disassembly and assembly section (30) includes clearances and wear limits for every component from the swing circle bearings to the idler cushion. If you are rebuilding a travel motor or replacing a cylinder seal, you need those numbers. Use the Komatsu PC27MR-2 PC30MR-2 PC35MR-2 PC50MR-2 Parts Catalog alongside this manual for part numbers. For a full set, pair it with the Komatsu PC27MR-2 PC30MR-2 PC35MR-2 PC40MR-2 PC50MR-2 Workshop Manual (same document) and the Komatsu PC27MR-2 PC35MR-2 Operation Manual for daily operating procedures.

Cooling System and Cylinder Standards in Section 10

Section 10 dives into the structure, function, and maintenance standards. You get the cooling system layout, power train components, swing circle, track frame, idler cushion, and track roller specs. The hydraulic cylinder section covers dimensions, disassembly notes, and seal replacement guidelines. The manual also details the CLSS (Closed Loop Swing System), multi-control valve, and PPC valve operation. If you are dealing with a cylinder that drifts or a swing brake that will not release, the standard value tables in this section are your first stop. The hydraulic pump and travel motor sections include exploded views and torque sequences. This is not a reprint—it is the original Komatsu shop manual from 2006, printed in Japan.

Does this manual cover engine overhaul procedures?

Yes, it includes compression pressure measurement, valve clearance adjustment, and fuel injection timing. For full engine disassembly, refer to the 68E-88E Series Engine Shop Manual.

What about the electrical system troubleshooting?

The E-mode section covers engine start/stop issues, work equipment lock, windshield wiper/washer, travel alarm, and air conditioner defects. Connector pin tables and T-adapter box instructions are included.

Can I use this manual for a PC50MR-2 with serial number 5001 and up?

Yes. The manual covers PC27MR-2 (15001+), PC30MR-2 (20001+), PC35MR-2 (5001+), PC40MR-2 (8001+), and PC50MR-2 (5001+). Serial number ranges are printed on the cover page.

Does this manual include torque values in imperial units?

The manual lists factory specs in metric (Nm) and includes conversion tables in the appendix. I recommend using a torque wrench calibrated in ft-lbs after converting. The values are not generic—they are Komatsu factory numbers.

Access the Factory Manual and get the full 621 pages of OEM repair data. Whether you are a home garage guy keeping a used PC30MR-2 running or a shop tech rebuilding a PC50MR-2 hydraulic pump, this document saves you the headache of guessing. For reference on related drivetrain concepts, compare with a Manual Transmission vehicle. If you need to understand torque converter differences, see Manual Transmission for background. But for this excavator, stick with the factory book.