5 Most Common Kubota KX040-4 Problems and Effective Fixes

A mini excavator is ideal for small to medium projects, and many in the construction business opt for them due to their flexibility. The Kubota KX040-4 is one of the best mini excavators, lauded for its power, versatility, and stability combination. Furthermore, it has a cozy interior and simple controls.

While there are plenty of amazing things to say about the KX040-4, you should also consider its problems to determine whether they are deal breakers. The most common Kubota KX040-4 problems include sudden stalling, a troublesome start, hydraulic issues, overheating, and tracks wearing out.

Let us look at this mini excavator’s setbacks and their solutions to help you see if it is a worthy acquisition.


Many KX040-4 users complain about its sudden stalls, a frustrating situation, especially at work. The issue is more frequent after leaving the compact excavator idle for some days.

You may experience stalling after a problematic start, characterized by jerking and strange engine sounds, as it is about to die.

Sometimes, the excavator may start trouble-free before it slows down and stops moving. Most of the time, stalling indicates a problem with the fuel system. You may have insufficient, dirty, or substandard fuel in the tank. A blocked exhaust pipe is a possible culprit, especially if working in tight spots with a lot of debris.


Start by checking the level of diesel in the tank. If sufficient, it may be dirty or low quality, prompting you to clean the tank. When leaving the excavator idle for some days, it is advisable to use a stabilizer to prevent fuel degradation.

Inspect other parts like the fuel line and exhaust pipe for blockages. You can easily unclog the exhaust pipe, but you may need professional help to work on the fuel line.

Starting Issues

A troublesome ignition is among the most recurrent Kubota KX040-4 problems, with the blame mainly lying on the electrical system. Users complain about a lengthy starting process and failure to start. Potential causes of this hitch are:

  • A dead battery
  • Corroded terminals
  • Loose connections
  • Faulty starter unit (motor, relay, or solenoid)
  • A bad fuel pump
  • A clogged fuel line
  • Insufficient or poor-quality fuel

When you start the Kubota KX040, you may notice jerking motions, dying immediately after cranking, and lights being dim or failing to turn on.

How to fix:

The first inspection area should be the battery and other electrical components. Jumpstarting will revive a dead battery. Nevertheless, you should replace it if it is too beat. Check the terminals for corrosion and clean them, if necessary, with sandpaper. Ensure the connections are firm and replace worn-out wires.

A loud click when starting the mini excavator indicates an issue with the starter. You might have a worn motor, relay, or solenoid. Part replacement is the best way to deal with starter troubles.

The problem may be the fuel line if the electrical unit is okay. Fill up the tank, if empty, with high-grade diesel. No change? If so, you might have to bring a professional to troubleshoot the fuel pump and line.

Hydraulic Troubles

Several Kubota KX040-4 reviews highlight its advanced load-sensing hydraulic unit. It is a convenient feature that saves you from the hassles of adjusting lever strokes to regulate oil flow depending on the load.

After prolonged use, the hydraulic unit may wear, noticeable via signs like leaking fluid and inconsistent or slow movements. These setbacks may affect the workflow and present safety hazards.

The hydraulic system failures may result from worn-out fittings, hoses, and seals in the case of leaks. Slow response and movement point to a faulty pump, trapped pressure, stuck thumb valves, and insufficient fluid.

The Fix:

Your Kubota may have a leak if you notice fluid dripping from the hydraulic system. Carefully inspect the assembly to determine the leaking spot. You solve this snag by replacing damaged hoses, seals, and fittings. 

You can refer to the KX040-4’s user manual to learn how to release trapped pressure. Repair or replace a bad pump and valves, though you might need an expert to help with troubleshooting. Fill up hydraulic fluid levels if low. Bleeding the cylinders is critical, especially if you suspect air or debris contamination.

Engine Overheating

Overheating is among the leading Kubota KX040-4 problems that users complain of. While it is a common trouble affecting numerous compact excavators, troubleshooting may be challenging due to many possible culprits.

Frequent blame-takers of this snag are:

  • Inadequate or low-quality coolant
  • Blocked or damaged radiator
  • Faulty water pump
  • Clogged air filter
  • Low oil levels
  • Overloading

We can see that overheating mainly results from a hitch with the engine’s cooling unit. Beware of signs like abnormal temperature gauge readings, a smoking or steaming engine compartment, stalling, and strange fan noises.

Overheating is serious and can cause more damage to the engine. You should stop the excavator if you suspect abnormal engine temperatures.


Start by turning off the engine and allow it to cool before you address the hiked temperatures. Top up the coolant if its levels are low with a high-grade product.

Inspect the radiator for clogs and damages. Clean clogged radiator fins with compressed air or pressurized water for the best results. Damages like leaks require specialized care or replacement if it’s excessive.

Inspect the water pump and hoses. If damaged, you can repair them with simple utilities like duct tape. However, if badly off, get new ones to avoid future recurrence.

You should regularly maintain air filters to avoid clogging and fast wear. If damaged, replace them with high-quality filters that will serve you well. Moreover, you should routinely change engine oil and work within the manufacturer-recommended load capacity.

Tracks Wear Fast

While the KX040-4 is a sturdy mini excavator, it has a soft underbelly in the form of its rubber tracks, which wear fast. The deterioration rate depends on applications, the terrain’s nature, and the use frequency.

Worn tracks affect fuel economy and stability. Poor stability results in vibrations, which affect its overall performance. If not fixed in time, the problem may extend to other parts of the excavator, mainly the undercarriage.


Appropriate operation will prevent rapid track wear. Here, you watch your terrain and avoid overloading. You should maintain the tracks by oiling the moving supporting components.

If working in punishing terrains, you can switch to steel tracks. Opting for mini excavator steel tracks grants you longevity at the expense of comfort, maneuverability, and fuel economy.

Kubota KX040-4 Specs

NameKubota KX040-4
Engine displacement1826 cc/ 111.4 cu. In.
Gross output42.4 Hp
Net output40.9 Hp
Hydraulic oil reservoir capacity11.1 gallons
Hydraulic oil system capacity19.6 gallons
Fuel tank capacity16.9 gallons
Ground clearance12.99 inches
Overall height97.8 inches
Overall width66.9 inches
Overall length200.1 inches
Operational weight9020 lbs.
Blade width66.9 inches
Blade height13.8 inches
Blade’s maximum lift above ground15.7 inches
Blade’s maximum drop below ground15.9 inches
Track typeRubber
Kubota KX040 4 problems

Is The Kubota KX040-4 Worth It?

Looking at Kubota KX040-4 problems, you realize they are commonplace among compact excavators. They are all solvable and avoidable with proper maintenance.

The Kubota KX040 4 is a worthy acquisition, with numerous selling points, such as its comfortable interior and almost noiseless operation. Beware of the highlighted troubles for a satisfying time operating the excavator. Take advantage of the equipment’s two-year warranty for out-of-hand hitches.