Description

Komatsu D85EX-15 Training Manual – Factory Diagnostic Procedures

You’ve got a D85EX-15 that’s running hot, pushing weak, or blowing smoke. The first thing you need isn’t a parts cannon – it’s a Komatsu D85EX-15 Training Manual that tells you exactly how to check each system without guessing. This 17-page document came from a PM clinic, not from some third-party rehash. It walks you through 18 specific checks: hot bushings, engine RPM, exhaust gas temperature, blow-by pressure, boost pressure, oil pressure, torque converter pressures, transmission clutch pressures, brake pressure, PPC pressure, work equipment relief, HSS main relief, fan speed, work equipment speed, hydraulic cylinder drift, and a data sheet to record your results. Every step is a factory procedure, not a generic suggestion.

I’ve seen too many guys skip the hot bushing check and end up with a seized link pin. Page 2 shows you exactly where to aim the digital emission thermometer right after shutdown – clockwise positions 35 through 7 indicate hot spots over 50°C. That’s the kind of specific data you need to keep the undercarriage alive. No interpretation, no “maybe” – just a temperature limit and a diagram.

Hot Bushing Check: The Manual’s First Test

The manual calls it “How to check Hot bushing of link pin.” After the machine stops, you walk around the left side and scan each pin position. The diagram on page 2 marks every pin from 1 to 41, with the master link at position 8. You touch the surface with the digital thermometer. If it’s over 50°C (122°F), that bushing is hot and needs attention. If it’s warm (35–50°C) you note it for next time. Cool means it’s fine. This one test prevents track failure and downtime. Do it after every shift if you want that undercarriage to last.

Get the temperature right and save a track.

Engine RPM Measurement – Factory Procedure

Page 3 and 4 lay out the exact sequence for measuring low idle, high idle, decelerator pedal RPM, and stall RPM. You start with parking lever ON, key ON, engine start. Then you set the service SW for 3 seconds, cycle the information SW, and read the display. For stall RPM they warn: never put the gear shift to F1. Use F3 at high idle. That warning alone is worth the price of the manual – one mistake there and you’ve torched your torque converter. The manual gives you the fuel dial positions and decelerator pedal setting for each reading. It’s all there: low idle at fuel dial MIN, high idle at MAX, decelerator pedal RPM at MAX with pedal pressed, and stall at F3.

Pressure Diagnostics: Seven Critical Checks

This manual covers torque converter inlet and outlet oil pressure, transmission main and clutch oil pressure, brake oil pressure, PPC oil pressure, work equipment relief pressure, and HSS main relief pressure. Each one has its own section with a dedicated procedure. You don’t guess where the gauge goes – the manual assumes you’re connecting to the factory test ports. If you need a complete transmission overhaul guide, pair this training manual with the Komatsu D85EX-15 2003 Workshop Manual – Factory OEM Specs for the rebuild side.

For a broader understanding of power flow, refer to Manual Transmission principles – but keep in mind that this machine uses a powershift transmission, and the training manual focuses on pressure checks rather than gear internals.

Use the OEM Specs for Accurate Diagnostics

Aftermarket manuals will tell you “check blow-by pressure” but skip the tool type or the acceptable range. This training manual gives you factory-specified steps and a data sheet on the last page to record your readings. You get blow-by, boost, exhaust gas temperature, engine oil pressure – all the numbers that tell you if the engine is healthy or headed for a rebuild. The 17 pages are lean: no filler, no history lessons. Just the procedure, a diagram, and a place to write results.

Another reason to stick with OEM: the wiring and hydraulic routing on a D85EX-15 can vary by serial number. This training manual is based on a specific PM clinic curriculum – the same one Komatsu techs use. You won’t find that in a generic guide. If you need operational details, grab the KOMATSU D85EX-15 D85PX-15 Operation & Maintenance Manual to complement this diagnostic manual.

Who Buys This Manual?

This manual is for anyone who owns, operates, or repairs a Komatsu D85EX-15. That includes heavy equipment mechanics, fleet maintenance supervisors, and experienced DIY owners who want to verify their own diagnostics instead of paying dealer rates. The procedures assume you can access the machine and have basic tools – digital thermometer, tachometer, pressure gauges. It does not cover full disassembly or rebuild. It’s a training manual, not a service manual. If you need a complete service manual, get the KOMATSU D85EX-15 D85PX-15 2004 Service Manual. For general transmission theory, Manual Transmission background helps but isn’t required.

Is this manual for beginner DIY mechanics?

Yes. If you can read a diagram and follow steps, you can use it. The language is direct and the procedures are numbered. No guesswork.

What specific pressures does it cover beyond engine oil and transmission?

The manual includes procedures for measuring torque converter inlet/outlet oil pressure, transmission main and clutch oil pressure, brake oil pressure, PPC oil pressure, work equipment relief pressure, and HSS main relief pressure. That’s seven distinct pressure checks, each with factory-specified steps and a data sheet for recording results. Page 3 gives you the engine RPM measurement sequence, and page 2 covers the hot bushing check. The 17 pages pack an entire PM clinic into a single document. You also get exhaust gas temperature, blow-by, boost, hydraulic cylinder drift, fan speed, and work equipment speed. It is a thorough diagnostic reference for anyone maintaining a D85EX-15.

Access the Factory Manual now and put these procedures on your bench. You will save hours of guesswork and avoid costly damage from skipped steps.