Is your machine acting up? What to check yourself, by symptom, before calling the technician

Before checking: make the machine safe

No check is worth an accident. Stop the machine on level ground and rest the work equipment on the ground —bucket, blade, ripper or stabilizers—, leaving no load on the hydraulic system. If the fault allows, Komatsu asks you to leave the engine at idle for about 5 minutes before shutting it off, so it cools progressively and the turbo slows down.

What you check is done by eye and on the gauges: leaks, levels, filters, coolers, bolts and guards. Opening, dismantling or adjusting components is the technician's work. In Komatsu's guidelines for its trucks, for example, the operator never touches the steering box.

Won't start or stalls by itself

Start with the simple things: that there's fuel and, if your machine has a battery isolator switch, that it isn't cutting the power: Komatsu asks you to apply it at the end of the shift and release it before starting.

Then look for water in the fuel. Komatsu asks you to drain the fuel tank before each shift, especially after days of idleness, to remove the water and sediment that settle at the bottom; and to check the pre-filter bowl: if you see water, drain it by loosening its valve. A machine that sat idle for days is the first suspect.

If it still won't start after that, call service.

• Is there fuel in the tank?
• Is the battery isolator released (not cutting power)?
• Did you drain the water from the tank and the pre-filter bowl?
• Still won't start? → Call service.

Overheating: high temperature

The first thing you can see is whether air is getting through. Komatsu asks you to check every day that the coolers are clean and that nothing that could damage them is stored there. On wheel loaders and dozers with a reversible fan, Komatsu says to reverse the fan after each shift so the coolers clean themselves, with the cab doors closed so dust doesn't get in.

Also check the coolant level, with the engine cold, and look for coolant leaks under the machine. If the temperature gauge reaches the red zone or the alarm comes on, stop working: carrying on hot can turn a cleaning job into an engine repair.

• Are the coolers clean, free of mud and objects?
• Did you use the reversible fan to clean them, if your machine has one?
• Is the coolant at level, checked cold?
• Are there coolant leaks?
• Temperature in the red or an alarm? → Stop and call.

Loses power or performs worse

Check the engine air filter's restriction indicator: Komatsu includes it in the daily check because a clogged filter starves the engine of air. Check the water in the fuel again, in the tank and in the pre-filter.

Also confirm the work mode. Komatsu machines have selectable modes: the excavators in the catalog have several work modes, the WB93R-5E0 backhoe has power and economy modes for the backhoe arm and the GD535-5 motor grader has economy and productivity modes. An economy mode on heavy work feels like a lack of power.

If the engine smokes more than usual or the loss of power continues, call service.

• How often should you replace a machine's filters and wear parts?
• How much fuel does your machine burn, and how do you measure it?

Slow, weak or leaking hydraulics

Did you warm up the machine? Komatsu asks you to start it and let it warm up for at least 5 minutes before working, and on excavators and loaders to move it for another 5 minutes without load before pushing it.

Check the hydraulic oil level and look for leaks: Komatsu asks you to report any hydraulic leak immediately. Check the hydraulic hoses and fittings: they shouldn't rub against anything that wears them. A dripping hose gets reported; don't patch it on site.

If the level is fine, there are no leaks and it's still slow or weak, call service.

• Greasing heavy equipment: how to do it right every day

A strange noise, knocks or something loose

Komatsu is clear: if you hear an unusual noise during operation, stop working and check the machine. Look for loose bolts, loose guards and damaged flexible hoses.

On tracked machines, check the undercarriage: track tension, that the tracks are free of mud, and whether there are leaks at the final drives, rollers or idler. Check the bucket teeth and corner guards or the blade's cutting edges. When greasing, if a grease fitting won't hold grease, ask for it to be replaced.

On trucks, Komatsu says: if there's noise in the steering, stop the unit and check the steering oil level; if there's noise in the engine, stop the unit and call support; if gears jump, don't force the transmission and ask for support.

• Daily inspection before operating a machine: the complete checklist
• How to choose the right excavator bucket

A warning light or a code comes on

Alarms exist to warn you before a fault gets serious. In Komatsu's guidelines for its trucks, the color tells you how critical it is: orange, you can keep operating but must contact support; red, you must stop the machine and report it. Your model's manual defines its own alarms: follow it.

Write down or photograph the exact code or message on the screen. On machines with KOMTRAX, caution codes also reach Komatsu technicians as an early warning, so they can analyze the data before the problem grows.

Never use the emergency stop to halt the machine unless it's a real emergency.

• What is KOMTRAX and what does it tell you about your Komatsu machine?

Before calling: what the technician needs

With good information, the technician arrives with the right part instead of making a diagnosis trip. Have ready:

• Full model and serial number, from the data plate.
• Hour-meter reading.
• What you saw, heard or smelled: the symptom in your own words.
• When it started and what you were doing at the time.
• Whether anything changed beforehand: a service, a part, fuel from a different source, days of idleness.
• A photo of the code or alarm, and of the leak if there is one.
• What you already checked from this guide and the result.

• How do you read your machine's data plate and serial number?
• New heavy equipment warranty: what it covers, what puts it at risk and when the extended one pays off

So it doesn't happen again: Komatsu's daily routine

Almost everything you checked in this guide is the routine Komatsu asks you to do every day before operating: look for leaks and loose parts, drain water from the fuel, check the air filter indicator, check levels, clean the coolers, check bucket or blade wear and grease the joints. At the end of the shift, machine on level ground, work equipment resting on the ground and 5 minutes at idle before shutting down.

Komatsu puts it this way: units are inspected and maintained every day to avoid unwanted stoppages in the operation.

• Daily inspection before operating a machine: the complete checklist
• Preventive maintenance for heavy machinery: how often, and what does it include?
• Greasing heavy equipment: how to do it right every day