Frequently Asked Questions

Q: Diesel engine can not start

1.    Fuel system failure: the diesel engine doesn’t ignite when rotated by the electric motor and there is no fuel in the fuel return pipe.

A. No air in the fuel system.

B. Fuel pipe clogged.

C. Fuel filter clogged.

D. Fuel pump doesn’t work or fails while working.

E. Insufficient fuel injection failed injection or fuel not atomized.

F. Injection pump speed governing lever placed in wrong position.

2.    Electric starting system failure

A. Misconnection of electric wires or inadequate grounding.

B. Insufficient battery capacity.

C. Fuel pump rod rack choked.

D. Electronic speed governor failure.

E. Fuel injection advance angle too earlier or too late, or even 180°apart. Engine not ignited.

F. Incorrect valve timing.

G. Long starting time or misfiring in cold environment.

Q:Inadequate output power of the diesel engine.

3. Fuel system fault : cannot increase rev and output power even when the throttle is increased.

A. Fuel pipe or filter is intruded by air or gets clogged.

B. Fuel supplied by the pump does not get atomized.

C. Inadequate atomization of the injector or injecting pressure too low.

4. Air intake and exhaust system fault: the exhaust smoke has a higher temperature and worse color than normal.

A. Air filter clogged

B. Exhaust pipes clogged or pipe joints too long or elbows having a small bend radius or Engine block overheating or ambient temperature too high or oil and coolant temperature too high or exhaust temperature too high .

Q: Abnormal sounds when the diesel engine is running

1. Drive gear wearing, enlarged clearance: abnormal sounds from the front cover; collision noise heard when the engine suddenly slows down.

2. No oil between the rocker adjusting screw and the pushrod spheric seat: squeaks of dry friction heard from the cylinder head.

3. Enlarged intake and release valve.

Q: Abnormal exhaust smoke color

1. Black smoke:

A. The engine overloaded

B. Uneven fuel supply among the cylinders

C. Inappropriate valve clearance and /or bad seal results in gas leakage

2. White smoke

A. Inadequate atomization of the fuel, fuel liquid drops ,injection pressure too low.

B. Incomplete combustion in individual cylinder (esp. in winter )when the engine is just started .

C. Air filter clogged, obstructing air intake

D. Piston ring choked or excessive wear; reduced flexibility; piston ring chamfer installed in wrong location, causing oil intrusion into the combustion chamber.

E. Engine constantly runs at low load (below 40% of rated output):enlarged clearance between piston and cylinder jacket, causing oil intrusion into the combustion chamber.

F. Excessive amount of oil in the oil pan.

Q: Abnormal engine oil pressure

1. Engine oil pressure drops and can not return to normal even through adjustment of the pressure control valve. Meanwhile, the readings on the pressure gauge fluctuant:

A. Oil pipe leakage

B. Air intrusion into the oil pump or lack of oil in the oil pan.

C. Serious oil leakage in such locations as the crankshaft thrust bearing, oil seal of the flanged end of the crankshaft, camshaft bearing and connection rod axial bush.

D. Rupture of the connecting oil pipe between rocker shafts; no oil injector is installed to lubricate the drive bearing or the oil injector is displaced from its fixed position.

E. Oil cooler or oil filter clogged; rupture of cooler.

2. No oil pressure ,the pointer of the oil pressure gauge is motionless:

A. Oil pressure gauge damaged.

B. Oil passage clogged.

C. Oil pump severely damaged or chocked because of unskilled installation.

D. Oil pressure control valve fails ,the spring damaged.

Q: Over-high oil temperature and excessive fuel consumption

1. Oil level in the oil pan drops quickly ;the color of the oil is dark; white smoke is seen form the oil refilling hole on the vent pipe and black smoke is seen from the exhaust pipe:

A. Oil of inappropriate grade is used

B.  Piston ring gets stuck or worn out; cylinder jacket gets worn out so that oil intrudes into the combustion chamber, combusting gas intrudes into the crankshaft case

C. Oil return hole of the piston oil control ring gets clogged with carbon deposits.

D. The elastic sealing of the piston oil control ring gets clogged with carbon deposits.

E.  The elastic sealing of the turbocharger (if equipped) fails to function

Q: Oil level in the oil pan rises

1.   The coolant infiltrates into the engine oil; yellow bubble floats on the oil; water vapor condenses on the surface of the vent pipe filter element:

A. Cylinder jacket water tight gasket damaged, resulting in water leakage.

B. Cylinder head gasket damaged, resulting in water leakage.

C. For wet oil cooler, the cooler element damaged, resulting in the mixture of cooling water and oil.

D. Cooling water infiltrates from the fresh water pump into the oil pan ;Leakage of water on the fresh .

Q: Outlet water too hot

1. There is air in the water pipe: little or no water flows through the outlet pipe, resulting in rising water temperature

2. There isn’t enough water being circulated. At high loads, the outlet water would become very hot and engine oil would also be too hot.

3. Fresh water pump or cooling fan doesn’t rotate fast enough.

4. The rotor blades of the fresh water pump gets damaged

5. The clearance is too wide between the rotor blade and the pump case.

6. In open circulation system, the water supply end is so low that the water pump is unable to suck up the water.

7. In closed circulation system, the radiator lacks water.

8. Water pipes get clogged.

A. In closed circulation system, the radiator surface is covered with dirt, affecting the heat emission.

B. Thermostat doesn’t work.

C. Water temperature gauge doesn’t’ work.

Q: Outlet water too cold

1. In open circulation system, the raw water intrudes into the engine.

2. Thermostat doesn’t work well or gets damaged.

3. Ambient temperature is low or the load is low.

Q: Oil fouls on the cooling

The element of wet oil cooler gets damaged.

Q: Electric starting system

1. Starter motor doesn’t work

A. poor contact at electric connections

B. poor contact at brushes

C. starter motor short circuit.

D. Inadequate charging of the battery or battery capacity too small.

E. poor contact on electromagnetic switch contact points.

2. Starter motor gear gets choked with the flywheel ring gear or starter motor gear can’t be disengaged:

A. starter motor not in parallel to the center of the flywheel ring gear.

B. sintered electromagnetic switch contacts.

3. Starter motor continues running after start button is released:

A. the moving contacts of the electromagnetic switch sintered with the connection screw.

B. starter motor governing screw, not adjusted properly.

4. Abnormal noises with the alternator

A. loose or broken bearings.

B. collision between rotor and stator.

5. Battery refuses charging or unable to provide strong current while voltage drops sharply; white lead sulfate crystals appear on the plates

Q: without no-load voltage when started

Connect terminal “E+” and “E-” to a 4-12V new battery, and maintain it for 2-3 seconds. (Pay attention to polarities)

Q: voltage too low

Check the rev

Q: voltage too high

Adjust AVR voltage-potentiometer

Q: The voltage is correct at no load while too low at load.

Let the alternator run at no load, check the voltage between “E+” and “E-” on AVR

Q: Voltage disappears during operation

Check AVR, arrestor, and rotating diode; replace any failing components.