Construction machinery problem guides
Find the symptom and open a guide to possible causes, safe checks and the information needed for further diagnosis.
Engine starting
Why will the excavator not start?
An excavator that will not start needs a first distinction: no cranking, slow cranking or normal cranking without firing. What to check and when to stop.
Read moreEngine cranks but will not start
The starter turns but the engine will not fire: compare cranking speed, smoke, fuel pressure, synchronization and intake/exhaust flow.
Read moreEngine will not start when hot: what to check
Starts cold but not hot? Compare cranking RPM, fuel pressure, synchronization and temperatures during the actual failed hot start.
Read moreEngine is hard to start when cold
Difficult cold starting: cranking speed, preheating, air in fuel, fuel pressure and compression. Note smoke and behavior after the first start.
Read moreEngine starts then immediately stalls
An engine that starts then stalls needs checks of shutdown timing, key release, fuel pressure and response to hydraulics or travel engagement.
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Engine operation and power
Engine stalls under load
The engine runs unloaded but stalls while working? Distinguish insufficient engine power from excessive hydraulic or transmission load.
Read moreWhy will the engine not rev up?
The engine runs but will not gain RPM. Compare requested and actual speed to distinguish control limiting from fuel, air, exhaust or excessive load.
Read moreEngine power loss: where to look
Engine power loss may involve fuel, air, exhaust, derate or machine load. Establish when the problem occurs and under which conditions.
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Exhaust smoke
Why does the excavator emit black smoke?
Black smoke does not automatically mean faulty injectors. Check air, boost, EGR, exhaust and load; note power loss and turbo noise.
Read moreBlack smoke and loss of engine power
Black smoke together with low power: check boost leaks, turbo, intake, exhaust and hydraulic load before blaming injectors.
Read moreWhy does the engine emit white smoke?
White diesel smoke: distinguish unburned fuel, vapor, coolant and cold-start behavior. Color alone does not identify the fault.
Read moreEngine smokes when accelerating
Smoke on acceleration: distinguish a brief transient puff from persistent heavy smoke. Check air, turbo, EGR, injection and hydraulic load.
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Engine oil
Low engine oil pressure: what to do
Do not keep working with low oil pressure. Verify actual pressure with a gauge, oil level/condition, filter, pump and engine condition.
Read moreOil pressure warning light flickers
Do not ignore a flickering oil light. Distinguish an electrical fault from genuinely marginal pressure, particularly at hot idle.
Read moreEngine oil level is rising
A rising oil level may mean fuel or coolant contamination. Track the rate of increase, oil condition and any link to DPF regeneration.
Read moreCoolant in engine oil
Coolant in oil compromises lubrication. Check the head, liners, block and engine oil cooler as well as the head gasket.
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Cooling
Why is the engine overheating?
Engine overheating: coolant level/flow, radiator pack, fan, thermostat, pump and load. Do not open a hot cooling system.
Read moreEngine overheats only under load
Normal temperature at idle but overheating while working: check radiator pack, airflow, coolant circulation and engine load.
Read moreCoolant is pushed out of the expansion tank
Coolant expulsion: overheating, cap, circulation or cylinder gases. Distinguish pressure after cold starting, warming and heavy load.
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Fuel system
Hydraulics
Why is the excavator’s hydraulic system weak?
Weak digging, lifting or travel: distinguish a system-wide hydraulic problem from one weak function and prepare useful diagnostic information.
Read moreWhy are the hydraulics slow?
Slow movement with normal force is not just a maximum-pressure problem. Check flow, pump control and whether one or every hydraulic function is slow.
Read moreWhy do the hydraulics weaken when hot?
Hydraulics that work cold but lose force or speed when warm need comparable measurements and internal-leakage checks at operating temperature.
Read moreWhy has only one hydraulic function stopped working?
Boom, arm, bucket or swing does not work while other functions are normal: follow the command through its circuit to the cylinder or hydraulic motor.
Read moreWhy does the boom or arm drift down?
Boom drift with the joystick in neutral: possible cylinder, control valve and load-holding valve leakage, and essential inspection safety.
Read moreWhy do the hydraulics bog down the engine?
The engine loses speed or stalls during hydraulic operation. Separate loading at hydraulic unlock from a single-function fault or lack of engine power.
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Travel and transmission
Why will the machine not move with the engine running?
Engine running but no travel: identify the drive type, then distinguish missing commands, pressure faults, brake release and mechanical seizure.
Read moreWhy will the excavator not travel forwards or backwards?
Travel works in one direction only. Compare commands and pressures, identify the drive type and compare both sides before replacing components.
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DPF, AdBlue and SCR
Why will DPF regeneration not start or finish?
The DPF requests regeneration but it fails to start or keeps stopping. Check enabling conditions, sensors, temperatures and filter loading before retrying.
Read moreWhy does an AdBlue or SCR fault limit machine power?
AdBlue/SCR faults and derate: check exact codes, restriction status, fluid quality, pressure, dosing, NOx readings and exhaust-system conditions.
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