Diesel Engine Common Faults and Troubleshooting

• • Diesel engine can not start
  1, Fuel system failure:
      (1)Air in the fuel system
      Check whether the fuel pipe joints are loosed, whether the pipeline has the air, get the air out of the fuel system   
      (2)fule pipeline are blocked
      Inspect the flow of pipeline
      (3)Fuel filter blockage
      Clean Cartridge filter or replace it
      (4)The fuel pump do not pump fuel or intermittently supply
      Check whether the tube is leaking, tubing filter is blocked. If it’s not like  above,should check tube and pump.
      (5)Fuel inject rarely, no fuel injection, or non-atomized fuel injection
      Split the injector out, and then connect to the high-pressure pump, the prized injection pump plunger spring , observe the spray condition,whash it if necessary.
      (6)The manipulating handle position is not correct.
      When starting, put the handle at the start location(700 ~ 900rpm)
  2, Electric starting failure
      (1) Circuit connecting mistake or poor contact. Check the wire connection is correct and reliable
      (2) Batteries power shortage Use battery with sufficient power or to put more the batteries in parallel connection
      (3) Between Starter motor brush and commutator,there is  no contact or poor contact Repair or replace carbon brush, use wood sandpaper clean commutator surface, and blow the dust, or  adjust spring brush pressure
  3, Cylinder compress pressure is less : normal fuel injection, but no ignition, the exhaust pipe with fuel in it .
      (1) Excessive wear of piston ring or cylinder liner. Replace the  piston ring, judge the wear condition ,consider to replace the  liners or not!
      (2) Valve leakage Check valve clearance, valve spring, valve guides and the seal of the valve seat , if poor seal,need to repair and grind.
      (3) Valve Clearance or combustion chamber volume is oversize Check piston whether the model match each other , if necessary, please measure combustion chamber volume or compressing clearance.
  4,Incorrect phase of valve distribution , adjust the correct valve clearance.
  5,Low ambient temperature: will get a long start time ,even can not start According to the actual ambient temperature, take corresponding low temperature starting measures .

• • Diesel power shortage
  1, Fuel system failure: no power or speed increasing by placing throttle to high level position
  (1) Fuel line, fuel filter has air or get blocked According to the before mentioned method ,get the air out of it, or replace fuel filter core
  (2) Poor fue supplying by  injection pump . Inspect, repair or replace delivery valve and seat
  (3) Abnormality of fuel injector ,low fuel pressure Observe or adjust the fuel injector spray pressure, and check the fuel injector nozzel or replace it if need to do so .
  2, Induction and exhaust air system failure:exhaust temperature is higher than normal ,different smoking color
  (1) Air filter blockage Clean air filter core or remove the dust of core,if necessary, replace them , and check the oil level of air filter ,to make sure it is normal or not .
  (2) Home-made exhaust pipe blockage or length too long, the turning radius is too small, or bend too much Remove the accumulated carbon in the exhaust pipe, redo exhaust pipe arrangement !bending point no more than 3, and has a large exhaust  cross-section .
  3, Diesel engine overheating, the ambient temperature is too high: oil and cooling water temperature is too high,high exhaust temperature. Check the cooler and the radiator, remove the furring; check  pipe diameter ,to make sure it is sufficient. if the ambient temperature is too high ,to improve ventilation , take other temporary cooling measures.

4, Cylinder head component failure: power is insufficient, performance decrease, but also have leakage, black smoke come from the inlet, have abnormal rapoon phenomena and so on.
(1) Air leakage between cylinder head and junction surface, when speed changes ,airflow will come from the cylinder head gasket : Cylinder head big screw  is loose or the gasket is damaged Accord to the provisions, tighten the big screw , or replace the cylinder head gasket, if necessary, scratch the junction surface, replace cylinder head gasket.
(2) Inlet, exhaust valve leakage strip inspect the inlet and exhaust pork,repair it and valve seat
(3) Valve spring damage  Replace of damaged spring
(4) Valve clearance incorrect Reset the valve Clearance to the provisions .
(5) injector air leakage or copper gasket damaged, piston ring is stuck , valve shaft stick with air leading cylinder cause compression inadequate Inspect it , clean it and replace damaged parts
5, connecting rod bearing shell and connecting rod surface abnormality: abnormal sound, and have oil pressure dcreasing phenomenon
Tear down the diesel Engine side cover, check connecting rod side clearance, check the link to find out if it can move forward and afterward.if it can not move, should repair connecting rod and replace connecting rod bearing.  

• • Diesel has abnormal sound during working
  1, Fuel injection time is premature, cylinder send out crisp rhythmic sound of metal     percussion Adjust fuel injection advance angle
  2, Fuel injection is late, the cylinder send out is vague percussion sound Adjust fuel injection advance angle
  3, Piston and cylinder gap is too large, sent out percussive sound, speed increases,the sound lounder Replace the piston or replace cylinder liners,it depends on the wear condition.
  4, Connecting rod bearing wear cause the gap larger, the crankshaft box can hear the sound of mechanical impacting during working , suddenly lower the speed, we can hear heavy and powerful percussive sound .Tear dowm connecting rod bearing, if necessary, should be replaced
  5, The crankshaft main bearing clearance is too small, send out special sharp and unpleasant sound during working , and increase the throttle, the sound will be londer and more clear; crankshaft main bearing radial clearance is too large, the functioning of a "scrape of a knife" sound Check the main bearings which send out the sound, if necessary, should be replaced
  6, Forward and afterward crankshaft thrust bearing wear, the axial clearance is too large, cause the crankshaft moving forward and afterward. When  diesel engine is work at idle speed, can hear the sound of collisions. Check the axial thrust bearing gap and the degree of wear if necessary, should be replaced
  7, Valve spring broken, tappet curved, push rod sleeve is wear, send out  slight rhythmic percussion sound from the cylinder cover.

• • Abnormal smoke of engine exhaust

1、The black smoking
(1)  Provisions about engine load Reduce engine load
(2)  Incorrect valves，clearance,leakage of valves and burning abnormal Check the valve. Clearance,tightness of valves and cylinder head.
(3) The advanced angle for fuel injection is too small,much retard of fuel injection, part of the fuel is burning in exhaust pipe Re-adjust the advanced angle for fuel injection
(4) Air input insufficiency, air cleaner intake pipe blocking, turbocharging internal combustion engine shell dirty and so on Clean out or remove deposit, replace them if necessary
(5) Valves or cylinder heads leakage as the result of worn piston rings or insufficient elasticity of rings Check or replace the valve springs. Tightness of valves and cylinder head
2、The white smoking
(1) Sometimes the injector with fuel drops, poor atomization, low injection pressure Re-adjust the fuel injection pressure, lap the needle valve, replace fuel injection nozzle if necessary
3、The blue smoking
(1)Blockage of the air filter,slack intake or much more oil in crankcase Overhaul or wash out the filter,reducing oil to prescriptive quantity.
(2) Oil leaks to combustion chamber as the result of worn piston rings or insufficient elasticity of rings Check worn piston rings ,replace it if necessary
(3) Oil leaks to combustion chamber by reason of too much clearance As the result of worn piston rings due to lowloading long.
Increase engine load moderately, choose the appropriate power accessories
(4) Too much lube oil in oil pan Add oil by carved lines
4、there is moisture condensation in the exhaust; cylinder liners cracks so that coolant entering the cylinder. Replace cylinder head

• • Abnormal oil pressure
  1. Oil pressure descend

　(1) Check and  tightness  the connector
　(2) Air leaked into the oil pump, insufficient oil in the oil pan Add oil to the provisions of plane
　(3) Serious leakage in  the crankshaft thrust bearing, crankshaft output flange seal side, the camshaft bearings and connecting rod bearing Check around, wear value in excess of the scope should replaced parts.
　(4) Blockage of the filter，leakage in the oil gasket  Timely clean-up, welding or changing core subsamples, such as oil filter was found to be iron or check the connecting rod bearing, Replace the connecting rod bearing if necessary; Check and replace gasket timely.

• • Common features of the trouble in electric starting system

1、No rotating the motor after starting 
(1) Circuitry touching bad Clean and tightened up connection head
(2) Electriccity brush touching bad Clean the surface of commutator or replace brush
(3) Short-circuit of starter motor Find ou and repair shortt circuit parts
(4) Inadequate charge or battery capacity is too small To charge or increase the use of batteries in parallel
(5) bad electromagnetic switch contacts Check the switch of electric or polished with sand paper
2、Start the motor in idling without power
(1) Bad brush head or bad jointing Clean the surface of solder in prison or replacement
(2) Wear of bearing sets Replace them
(3) The magnetic field windings or armature windings partial short-circuit Find out and repair short circuit parts
(4) Electromagnetic switches Singeing contact, poor contact Check the switch contacts, and polished with sand paper
3、The starting motor gear and the flywheel ring gear apical tooth or the starting motor gear cannot draw back
(1)  Center of Starter and Flywheel Gear Ring non-parallel Reinstall the starter and remove the parallel (2) Electromagnetic switch contacts burned together Check the switch contact and grind it
4、tarter button was torn off and the starter motor continue to operate
(1) Electromagnetic switch moving contact with the screw rod burning in prison
(2) Maintenance
(3) Re-adjust
5、No or insufficient current of  charging generator
(1) Breakage or Short-circuit Of silicon diode, magnetic field coils, rotor coils Replace and repair them
(2) Energizing loop abruption or short circuit energizing loop Connect the broken wires
(3) The triangle rubbered tape wears or the tensioning force is insufficient Replace belt or adjust tension force
(4) damage to charge ammeter Replace them
(5) Access lines mistake Check and correct the mistake
6、The charge current instability
(1)Carbon stains, wear or poor contact, lack of Brush spring pressure Clean the surface of solder in prison or replace carbon brush
(2) silicon diode press-fit loose Department Replacement of components, together with the radiator
(3) Regulator bad jointing with internal components or bad contact Re-welding or No. 0 Sand Paper polished
(4) Triangular rubber belt loose Re-adjust tensioning force
(5) line wiring loose Check and tightness
7、Generators get hot because of the  large Charge current and  high voltage.
(1) short circuit of magnetic field wiring or magnetic field coils Maintenance
(2) The rotor winding short-circuits, bumps with the stator scratches Maintenance, go down frustrate knife encounter with the surface
(3) regulation of voltage too high Re-adjust to the provisions of the value of
(4) Transistor regulator last stage power tube zero-stage and collecting electrode short circuit Replacement power tube
(5)In the mode of vibrations voltage regulator's magnetizing coil abruption or short-circuits and the instrument multiplier burns out and so on Re-adjust or replace  
8、Abnormal noise during generators operating
(1) Bearing loosening or fracture Replacement
(2) The rotor and stator encounter File down the surface
9、when the battery temperature height, voltage low, the proportion of low. Recharging the smaller end of the bubble or bubble happened late on the internal short-circuit the battery As a result of sediment at the bottom of the battery caused by excessive short-circuit may be battery discharge, poured electrolyte repeated washing with distilled water and then recharged. It should be opened or replacement of the bulkhead or plate, or sent to the factory repair  for other reasons