Description

Komatsu D37EXi-23, D37PXi-23, D39EXi-23, D39PXi-23 Workshop Manual

You have a D37EXi-23 or a D39PXi-23 in the bay with a fuel pressure complaint, and the aftermarket PDF you obtained says “tighten to spec” but doesn’t give you the torque. That’s because it wasn’t printed by Komatsu. I’ve seen techs chase a charge pressure problem for three hours because they used a generic diagram. This Komatsu D37EXi-23, D37PXi-23, D39EXi-23, D39PXi-23 Workshop Manual is the OEM book – 1699 pages of factory procedures, not a third-party rehash. If you need the bleed procedure for the fuel system, it’s in section 30 under “Bleeding air from fuel system.” If you want the HST charge pressure test, it’s on page 73 of the Standard value tables. No guessing.

Engine and Cooling System: What This Manual Covers

Section 10 breaks down the engine and cooling system. You get the VFT (Variable Geometry Turbo) layout, the EGR system piping drawing, the KCCV ventilator, and the cooling fan motor circuit. The manual tells you how to test the fan speed and the fan circuit oil pressure – both are in the Testing and adjusting section (30-xx). It also covers the oil cooler bypass and HST charge safety valve. If you’re replacing a belt for the alternator or A/C compressor, there’s a specific procedure that lists the belt tension gauge part number. I’ve seen guys snap a belt because they guessed the tension. Don’t.

Testing and Adjusting HST Oil Pressure

The hydrostatic transmission (HST) on these machines is finicky about oil pressure. The manual dedicates a sub‑section to “Testing and adjusting HST oil pressure” under the Power train group. It tells you which port to tap, what pressure you should see at idle versus full throttle, and the exact shim thickness to adjust the charge pump relief. Every spec is in Imperial units – psi, ft‑lbs, inches. You also get the procedure for testing if the machine travels straight, and how to adjust the deceleration/brake pedal. If you skip the straight‑travel test, you’ll end up with a dozer that wants to crab when you’re trying to cut a grade.

Standard Torque Tables and Fluid Specs

Section 20, “Standard value tables,” includes the standard service value table for engine, machine, and electrical system. There’s a separate table for fuel, coolant, and lubricants in the Specification chapter (01). The manual gives you the conversion table (metric to Imperial) and the standard tightening torque table for bolts and nuts. Need the torque for the final drive flange bolts? It’s in that table. Never use a torque wrench setting from a generic chart – Komatsu’s values account for the thread lubricant and clamp load. I’ve had customers bring in stripped threads because they used a general “grade 8” torque value.

Why Factory OEM Documentation Matters

Aftermarket manuals often skip the electrical system entirely or give you a simplified schematic that doesn’t match the real harness. This book has the full electrical control system section, including the machine monitor system, KOMTRAX system, and sensor locations. The “How to read electric wire code” section (00-41) explains the color codes and connector pin numbers. When you’re diagnosing a no‑start condition, you need the exact resistance values for the crank sensor. Those are in the standard value table for electrical system. I’ve fixed three machines this year with a multimeter and this book that other shops had condemned as “bad ECM.”

Fuel System Handling and Safety

The preface includes a dedicated sub‑section “Handling equipment of fuel system devices” (00-26). It tells you how to bleed air, check for leakage, and handle no‑injection cranking mode. There’s also a procedure for writing compensation values when you replace an injector or the engine controller. If you don’t reprogram those compensation values, the engine will run rough and smoke. The manual warns you about the high‑pressure fuel lines – they have to be retorqued after a thermal cycle. That’s not something a DIYer would know unless they read page 00-26.

If you’re working on the undercarriage, Section 10 covers track frame and idler cushion adjustment. Section 30 tells you how to adjust idler clearance and test track tension. You’ll need a sprocket wear check, too. All the tools required are listed in “Tools for testing and adjusting” (30-xx). Don’t try to improvise a pressure gauge for the work equipment circuit – the manual gives you the exact thread size and pressure range.

Related manuals for other Komatsu models you might have in the fleet:
Komatsu WA65-5 WA70-5 WA80-5 2005 Workshop Manual
Komatsu WH609-1E0 WH613-1E0 WH713-1E0 WH714H-1E0 WH716-1E0 Workshop Manual
Komatsu PW95R-2 Workshop Manual – 520 Pages of Factory Specs

For general background on Manual Transmission systems in heavy equipment, the principles are similar but the control circuits vary by model. Check Manual Transmission fundamentals if you’re cross‑training.

Does this manual cover the D37PXi-23 with a ripper attachment?

Yes. The manual includes the ripper PPC valve, angle control EPC valve, and the isolation procedure for hydraulic drift in blade and ripper.

How do I know which serial numbers this manual applies to?

It covers D37EXi-23 serial 80179 and up, D37PXi-23 80179 and up, D39EXi-23 90404 and up, D39PXi-23 90404 and up. Check your machine’s serial plate.

You get the job done faster when the torque specs and wiring pinouts are right in front of you. Access the Factory Manual and stop fighting bad data.