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Komatsu D31E, D31P, D31PL, D31PLL, D31S 1997 Service Manual – What You Actually Get

You’ve got a Komatsu D31E, D31P, D31PL, D31PLL, D31S 1997 Service Manual showing up on your bench – that’s the real OEM book, not a third-party rehash. I’ve torqued enough Komatsu head bolts to tell you: if you don’t have the factory numbers for the Transmission control Valve or the Brake Cylinder adjustments, you’re going to waste time and maybe damage something. This is a 671-page PDF from Komatsu America, dated May 1997. It covers the D31E, D31P, D31PL, D31PLL, and D31S models. No aftermarket hogwash.

I’ve seen guys skip the step where you measure blow-by pressure before tearing into a low-power complaint. Then they replace half the engine and still have the same symptom. This book stops that. Section 20 – Testing and Adjusting – gives you the standard value tables for engine, chassis, and electrical systems. Page 1 shows the copyright and original file name. You’ll know exactly what you’re working with.

7 Systems Covered in This Komatsu D31E, D31P, D31PL, D31PLL, D31S 1997 Service Manual

The Table of Contents is laid out like a real shop manual – not a collection of blog posts. Section 10 covers Structure and Function: power train system, damper and universal joint, transmission pump, Hydroshift Transmission, transmission control valve, steering control, steering cylinder, brake cylinder, PPC valve, bevel gear shaft and steering clutch, steering brake, final drive, track frame, main frame and suspension. That’s a lot of metal moving under pressure. Each subsection has hydraulic circuit diagrams and piping schematics. Want to bleed air from the steering circuit? Page 20-? – but trust me, the method is in the Testing and Adjusting chapter with specific valve clearance and PPC valve adjustment procedures.

Transmission Control and PPC Valve Adjustments

If you touch the transmission control linkage without the factory specs, you’ll create a shift problem that takes hours to undo. The manual has a dedicated subsection for Transmission Control and Transmission Control Valve. It also walks you through adjusting the travel of the inching pedal and the brake pedal travel. For the PPC valve, you adjust it with a pressure gauge – no eyeballing. The standard value table for chassis includes oil pressures for power train, steering, and work equipment. Don’t trust your memory; use the table on page 20‑? (the testing section).

What’s in the Testing and Adjusting Section?

This is the part that separates a $30 generic CD from a real manual. Section 20 lists standard values for engine (compression pressure, blow-by pressure, injection timing) and chassis (oil pressures, brake lining clearance). There’s a complete table of required tools – you’ll see things like a flowmeter, pressure gauge, tachometer. Then step‑by‑step procedures: measuring engine speed, adjusting valve clearance, bleeding air from fuel circuit, measuring power train oil pressure, adjusting brake lining clearance. Even troubleshooting charts for the engine (S‑mode) covering starting, smoking, oil consumption, overheating. You follow those charts, you don’t swap parts blind.

Hydroshift Transmission: Factory Disassembly Specs

Most aftermarket “manuals” give you a generic exploded view. This one – from Komatsu – includes the Hydroshift Transmission subsection under Power Train System. Section 30 (Disassembly and Assembly) isn’t in the OCR excerpts I have, but based on the official structure, it’s there. The book has 671 pages of real procedures. If you’re rebuilding the final drive or servicing the steering clutch, you want the factory clearances and torque values. Anything else is a liability.

Understand the Steering and Brake Systems

Steering cylinder, brake cylinder, PPC valve, steering brake – these are hydraulic circuits that can kill you if you don’t know the bleeding procedure. The manual covers bleeding air from the steering circuit and from the angle cylinder circuit. It also shows adjusting the brake pedal and steering brake cylinder. One common mistake is over-adjusting the brake lining clearance. The standard value table gives you the spec. Page 2 of the PDF lists the entire contents. That’s not a guess; that’s a factory table of contents you can reference.

Factory data, not guesses.

Source Authenticity – Why OEM Matters

This is the original Komatsu publication. The cover page says “This material is proprietary to Komatsu America International Company” – no third-party license, no reprint. The file name is Komatsu_D31E-D31P-D31PL-D31PLL-D31S_1997_Service_Manual_en-35309004907.pdf. That’s the genuine PDF from the factory. When you buy from AutoRepairManuals, you get the exact same PDF the dealer techs use. I’ve seen shops lose warranty claims because they used a non-OEM torque spec. Don’t be that guy. Related manuals you might need: Komatsu D31 and D37 Series Shop Manual, Komatsu D31E D31PL D37E-5 Service Manual – 172 Pages OEM, Komatsu D31S Workshop Manual – OEM Factory Specs.

FAQ

Does this manual cover the D31Q model too?

Yes. The cover says D31S,Q‑20. It includes D31Q‑20 along with the other models listed.

What about the electrical system?

Section 10 includes an electrical circuit diagram, engine control, monitor system, and sensors. The testing section has a standard value table for electrical system and troubleshooting charts for engine starting and charging issues. You’ll find connector handling and checks before troubleshooting. Expect wiring diagrams but no pin‑out tables – those are usually in the separate electrical manual.

Are the torque values for the transmission control valve given in ft‑lb?

Yes. All torque values in this manual are in imperial units (ft‑lb, in‑lb). The standard value table for chassis specifies tightening torques for transmission, final drive, and steering components. For the transmission control valve, look in Section 20 under “Standard Value Table for Chassis.”

Do I need special tools?

You need a flowmeter, pressure gauge (0‑600 psi), tachometer, and a feeler gauge set. The manual has a table of required tools in Section 20. For bleed procedures you’ll need a catch bottle and a helper for the pedal.

You want the Komatsu factory procedures – not a third-party rewrite – for your D31E or D31S. This manual gives you every spec Komatsu printed in 1997. Access the Factory Manual and get the real data. If you’ve got a D31P or D31PL with a fussy Hydroshift, these pages will save you from rebuilding it twice. For more on how a Manual Transmission works in a bulldozer context, check Manual Transmission and Manual Transmission for videos. But for the actual service data, you need this book.