The motor grader/Niveleuse/Motoniveladora is the main machine used for shaping and leveling operations in earthmoving projects and is widely used in large-scale ground leveling operations such as roads and airports.
The engine of a motor grader/Niveleuse/Motoniveladora is its core power source and is usually required to have high torque, durability and the ability to adapt to harsh working conditions.
Common failures involve multiple systems such as mechanical, fuel, cooling, lubrication, and electrical.
The following is a detailed description of common fault types, cause analysis and maintenance methods of grader engines:
1. The engine cannot start or starts with difficulty
Le moteur ne démarre pas ou démarre difficilement
El motor no puede arrancar o arranca con dificultad
(1). Fault phenomenon**
- No response when starting, or the engine shuts down immediately after starting;
- The startup time is too long, accompanied by abnormal noise or black smoke.
(2) Possible causes**
- **Fuel system problem**:
- Insufficient fuel or poor fuel quality (containing water or impurities);
- The fuel filter is clogged;
- Poor atomization or stuck of the injector;
- High pressure fuel pump fault (insufficient pressure in common rail system).
- **Electrical System Issues**:
- The battery is low or the connection is loose;
- The starting motor or relay is damaged;
- Sensor failure (crankshaft position sensor, camshaft sensor signal abnormality).
- **Mechanical issues**:
- Insufficient cylinder compression pressure (valve leakage, piston ring wear);
- Timing gear misalignment (wrong valve timing).
(3). Maintenance method**
- **Check the fuel system**:
- Replace with clean diesel and clean the fuel tank;
- Replace the fuel filter and check whether the fuel line is unobstructed;
- Test the injector injection pressure, clean or replace the injector.
- **Check the electrical system**:
- Measure the battery voltage (normal value is above 24V), charge or replace;
- Check the starting circuit, repair the broken circuit or replace the damaged parts;
- Use a diagnostic tool to read the fault code and calibrate or replace the sensor.
- **Mechanical Overhaul**:
- Measure the cylinder compression pressure (normal value 2.5~3.5 MPa), repair the valve or replace the piston ring;
- Check the timing gear mark and adjust the valve timing.
2. Insufficient engine power
Puissance moteur insuffisante
Potencia del motor insuficiente
(1). Fault phenomenon**
- Power drops during operation, and there is noticeable power loss when climbing a slope or carrying a load;
- The exhaust pipe emits black smoke (incomplete combustion) or blue smoke (burning oil).
(2) Possible causes**
- **Intake system blocked**:
- The air filter is dirty and the air intake is insufficient;
- Turbocharger fault (impeller stuck, pipe leak).
- **Insufficient fuel supply**:
- Low-pressure fuel line is blocked (fuel filter, fuel pipe);
- The high pressure oil pump is worn or the pressure regulating valve fails.
- **Combustion Abnormality**:
- Injection timing deviation;
- Poor cylinder sealing (piston ring wear, cylinder liner strain).
- **Exhaust System Problem**:
- Exhaust pipe or muffler is clogged;
- EGR valve stuck (excessive exhaust gas recirculation).
(3). Maintenance method**
- **Clean or replace the air filter**, check the tightness of the supercharger pipeline;
- **Clean the fuel line** and test the high-pressure fuel pump pressure (the common rail system pressure needs to reach 1600~2000 bar);
- **Adjust injection timing** (via ECU or mechanical adjustment);
- **Check the cylinder tightness**, bore the cylinder or replace the piston ring if necessary;
- **Clean the carbon deposits in the exhaust pipe** and check whether the EGR valve is flexible.
3. Abnormal noise and vibration of the engine/Ruido y vibración anormales del motor
Bruit et vibrations anormaux du moteur
(1). Common abnormal noise types**
- **Knocking sound**: The piston pin is loose and the connecting rod bearing is worn;
- **Metal friction sound**: Timing gear wear, turbocharger impeller hitting the shell;
- **Periodic “clicking” sound**: Valve clearance is too large or hydraulic tappet fails.
(2). Diagnostic steps**
- Use a stethoscope to determine the location of the abnormal noise (upper part, lower part or accessories of the cylinder);
- Judging by the speed change: when idling, it is obviously more likely to be a valve mechanism problem, and when accelerating, it is obviously more likely to be a connecting rod or crankshaft problem.
(3). Maintenance measures**
- **Adjust the valve clearance** (adjust to 0.2~0.4 mm in cold engine state);
- **Replace worn bearings or gears** (engine disassembly required);
- **Check turbocharger** balance and replace assembly if necessary.
4. Engine overheating/Surchauffe du moteur/Sobrecalentamiento del motor
(1). Cause of failure**
- **Cooling system failure**:
- Insufficient or deteriorated coolant;
- Water pump impeller is damaged, thermostat is stuck;
- Radiator is clogged or fan belt is slipping.
- **Combustion Abnormality**:
- Too late injection leads to prolonged afterburning period;
- Cylinder head gasket is damaged (hot gas leaks into the cooling system).
(2) Solution**
- **Refill or replace coolant** (add antifreeze in proportion);
- **Check the water pump flow** and replace the damaged thermostat;
- **Clean the dirt on the radiator** surface and adjust the tension of the fan belt;
- **Correct injection timing**, replace cylinder gasket.
5. Abnormal oil pressure/Pression d’huile anormale/Presión de aceite anormal
(1). Fault manifestation**
- **Low oil pressure**: The warning light comes on, accompanied by increased engine noise;
- **Oil pressure is too high**: The pressure gauge pointer is out of limit, which may be caused by oil circuit blockage or pressure regulating valve failure.
(2).Maintenance points**
- **Check the engine oil level**, add or replace the engine oil (the oil grade must meet the requirements);
- **Clean or replace the oil filter**;
- **Check the oil pump for wear** (gear clearance exceeding 0.2 mm requires replacement);
- **Check crankshaft bearing clearance** (excessive clearance will cause pressure relief).
6. Emission system failure (for National IV/Tier 4 models)
Fallo del sistema de emisiones (para modelos National IV/Tier 4)
(1). Frequently Asked Questions**
- **DPF blockage**: Exhaust back pressure increases and engine torque is limited;
- **SCR system failure**: Abnormal urea injection, NOx emissions exceeding the standard.
(2) Treatment method**
- **DPF regeneration**: removes particulate matter through high temperature combustion (manual or automatic regeneration);
- **Check the urea pump and nozzle**, and clean the urea crystals;
- **Replace the failed NOx Sensor**.
7. Daily maintenance and prevention
Entretien quotidien et prévention
Mantenimiento diario y prevención
(1). **Regularly replace the “three filters”** (oil filter, fuel filter, air filter);
(2). **Monitoring instrument data**: Immediately stop the machine for inspection when water temperature, oil pressure, or speed is abnormal;
(3). **Use regular oil**: Avoid damage to the fuel injection system caused by inferior diesel;
(4). **Winter preheating**: Preheat the coolant and engine oil before starting in cold conditions.
**Summarize**
Engine failure requires a comprehensive diagnosis by combining “looking (smoke), listening (abnormal noise), measuring (pressure/voltage), and reading (fault code)”. For complex failures (such as electronic control system problems), it is recommended to use special diagnostic equipment and cooperate with the manufacturer’s technical support. Regular maintenance is the key to reducing failures and can significantly extend the life of the engine.
Une panne moteur nécessite un diagnostic complet combinant « regarder (fumée), écouter (bruit anormal), mesurer (pression/tension) et lire (code défaut) ». Pour les défauts complexes (tels que les problèmes avec le système de contrôle électronique), il est recommandé d’utiliser un équipement de diagnostic dédié et de coopérer avec le support technique du fabricant. Un entretien régulier est la clé pour réduire les pannes et peut prolonger considérablement la durée de vie de votre moteur.
La falla del motor requiere un diagnóstico integral que combine “mirar (humo), escuchar (ruido anormal), medir (presión/voltaje) y leer (código de falla)”. Para fallas complejas (como problemas con el sistema de control electrónico), se recomienda utilizar equipos de diagnóstico específicos y cooperar con el soporte técnico del fabricante. El mantenimiento regular es la clave para reducir las averías y puede prolongar significativamente la vida útil del motor.
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Post time: Apr-08-2025