Description

Komatsu PC75-1, PW75-1, WB70A-1, WB91R-2, WB93R-2 Technical Manual – Factory OEM

I've been turning wrenches for 28 years. When a Komatsu shows up with a dead cylinder or a leaking head gasket, the first thing I look for is the factory manual – not a photocopy, not a scan from some forum. Komatsu PC75-1, PW75-1, WB70A-1, WB91R-2, WB93R-2 Technical Manual is the real deal: 201 pages printed from the OEM source, covering the 4D98E, 4D106, and S4D106 diesel engines. No aftermarket re-hash that guesses the torque values – this is what Komatsu technicians use.

What Makes This Factory Manual Different?

Flip to page 1 and you'll see the exact engine serial number mapping for each model – PC75-1, PW75-1, WB70A-1, WB91R-2, and WB93R-2. That alone saves you from ordering the wrong parts. The table of contents on page 5 shows 12 major sections: General Information, Safety Precautions, Troubleshooting, Check and Adjustment, Engine Assembly, Lubrication System, Cooling System, Fuel System/Governor, Turbocharger, Starter, Alternator, and Special Tools. Each section was written by Komatsu engineers, not a marketing team. Aftermarket manuals skip the safety warnings and often get the torque values wrong. This one doesn't.

You'll find the torque specifications for standard bolts and nuts in section 1.8 (Moments of tightening of standard bolts and nuts). That's the kind of detail you need when you're reassembling a cylinder head at 6 PM on a Friday.

Engine Assembly – Torque Values You Can Trust

Section 4 (Engine Assembly) covers the cylinder head, gear/camshaft gear train, and cylinder block. If you've ever used a generic manual that says "tighten head bolts to spec" without listing the sequence, you know the pain. This manual gives the exact tightening order and torque values for the head bolts. Workshop tip: always use a torque wrench that's been calibrated within the last year. The manual lists the special tools needed – see section 11 for the complete list. Never reuse head bolts unless the manual says you can – on these Komatsu engines, some are torque-to-yield.

Section 3.5 covers valve clearance adjustment. The spec is given in millimeters, and the procedure requires a feeler gauge and a screwdriver. Simple? Only if you have the right numbers. This manual gives them.

Fuel Injection System – Don't Guess the Timing

Section 7 (Fuel System/Governor) is where the real value lives. It covers the injection pump, nozzle, feed pump, and governor. Section 3.6 tells you how to check injection pressure and spray pattern – critical for a Komatsu that's smoking or losing power. Section 3.7 walks you through checking and adjusting injection timing. Without factory specs, you're chasing your tail. The manual also includes a troubleshooting table (section 2.1) that ties common symptoms to specific fuel system causes.

For the turbocharged engine (4TNE106T), section 8 gives the full turbocharger service procedure – disassembly, cleaning, inspection, and reassembly. Torque specs for the turbo mounting bolts are listed in section 12.4. Don't guess – use the manual.

3 Safety Rules I've Seen Ignored

Section 0 (General Safety Rules) isn't just filler. Rule (C): "Use proper tools and equipment." I've watched a guy use Channel Locks on an injector line and wonder why it leaked. The manual tells you which special tools are required – section 11 lists them all. Rule (D): "Use genuine Komatsu parts, oils, and greases." Aftermarket seals fail. Rule (E): "Follow tightening torques." Every fastener matters, from the water pump bolts to the main bearing caps. Ignoring these rules costs you parts and time.

Who Should Buy This Manual?

If you own a PC75-1 excavator, a PW75-1 wheeled excavator, a WB70A-1 backhoe, or a WB91R-2/WB93R-2 backhoe loader, you need this. It's also useful for shops that service these models. I've used it to rebuild a PW75-1 engine – the injection timing procedure alone saved me three hours of trial and error. The manual covers the complete engine: lubrication system (section 5), cooling system (section 6), starter and alternator (sections 9-10). It even includes storage procedures (section 3.12) for machines that sit idle.

For transmission overhaul, you'll need a separate manual. For a general understanding of manual transmissions, see Manual Transmission on Wikipedia. But this engine manual won't help you there. Transmission rebuilds require their own specs; check Manual Transmission for basics.

Does this manual cover the WB91R-2 with a 4D106 engine?

Yes, it covers the WB91R-2 and WB93R-2.

How detailed are the fuel system procedures?

The manual includes detailed procedures for the entire fuel system, from the injection pump to the nozzles. It lists special tools needed, like the injector pressure tester, and gives the exact pressure values. If you've ever had a Komatsu that wouldn't start because the timing was off, you know how valuable this is. The manual also covers the governor adjustment and the maximum no-load speed setting. Section 7.6 lists all the special tools. Without this, you're guessing, and that costs you money and time.

Related Manuals

• Komatsu WB91R-2 WB93R-2 Workshop Manual – 504-Page OEM
• Komatsu WB91R-2 WB93R-2 Service Manual – Factory OEM 280 Pages
• Komatsu WB91R-2 WB93R-2 Operators Manual – Factory OEM Specs

Access the Factory Manual now and get the real specs – not someone's best guess. Your Komatsu deserves the correct torque values and the right procedures. Click the link below to add this 201-page technical manual to your cart.