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According to the engine sound to teach you to check the fault

When the engine failure, often accompanied by the occurrence of certain abnormal sound, based on the experience of old master basic maintenance can determine what failures occurred, the following few failure cases, we hope to help.

First, the valve beep
Phenomenon:
(1 ) diesel cold start, the sound will appear.
( 2 ) the sound has nothing to do with speed , but occasionally crisp sound , will soon disappear, seriously , this noise will occur frequently .
(3 ) accompanied by the sound of individual cylinder does not appear to work , the normal sound disappears .

Reason:
( 1 ) valve seat inserts in the head with a small amount of interference over Songkuang caused .
Inappropriate materials ( 2 ) selection of the valve seat , the thermal expansion coefficient is too small.
Diagnostics and Troubleshooting :
( 1 ) When noise occurs , accompanied by the phenomenon of individual cylinders inoperative ; sound disappears and normal diesel engine , the cylinder can be diagnosed as not working valve seat plate.
( 2 ) measurement of the cylinder by the cylinder -by- cylinder pressure gauge , low pressure cylinder to cylinder abnormal sound .
Second, the camshaft audible
Phenomenon:
( 1 ) medium-speed diesel engine , heavy sound emitted from the side of the cylinder block camshaft ; at high sound nebulous .
( 2 ) when the single-cylinder off the oil , sound the same.
Nearby ( 3 ) camshaft bearings with vibration.
Cause:
( 1 ) camshaft journal bearing and the gap is too large, Songkuang .
( 2 ) bearing alloy camshaft bearings loose or ablation , flaking or excessive wear .
( 3 ) camshaft camshaft axial clearance is too large or bent .
Diagnostics and Troubleshooting :
( A ) most of the diesel in the speed of sound , auscultation with a stethoscope in the cylinder , and if accompanied by a strong shock sound somewhere , where the bearing ring can be diagnosed .
( 2 ) Test the sound off the oil change, can slowly transform the throttle , if the idle sound clear, distinct sound when medium speed , high speed when the sound becomes weakened by a messy , can be diagnosed as camshaft bearing axial clearance is too large or loose.
Third, the valve leak
Phenomenon:
When a fault occurs , there will be difficulty in starting the engine , the exhaust pipe blasting , smoke , fuel consumption increases , and the emergence of the phenomenon of abnormal sound .
Reason:
( 1 ) valve and valve seat face abrasion, erosion, poor sealing and leak.
( 2 ) valve and valve seat face a coke , valve closed lax and leak.
( 3 ) valve and valve guide clearance is too large , the valve stem shaking, leading to lax and then close the valve leak .
( 4 ) the valve stem in the valve guides astringent or stuck valve can not move up and down .
( 5 ) valve spring loses its elasticity or spring break.
Diagnostics and Troubleshooting :
After the cause when the fuel ignition system failure , a failure can not determine the cylinder pressure measurement , measurement of the cylinder pressure or vacuum of the intake manifold , which can more accurately determine the fault , the measurement of the cylinder pressure , cylinder pressure leak valve lower than the other cylinders .
Fourth, the liquid ring behind column
Phenomenon:
When the diesel engine running , there rhythmic sound, at idle apparent weakening or disappearance of more than medium speed .
Reason:
( A ) diesel oil is too high or too low result pages of lubricating oil into the air bubbles in the hydraulic tappet , the elastic gas noise.
( 2 ) oil pressure is too low .
( 3 ) oil pump strainer is damaged or broken , the air sucked oil to go.
( 4 ) fluid behind the column failure.
( 5 ) the use of poor quality lubricants.
Diagnostics and Troubleshooting :
( 1 ) Check the oil level , as the case may be added or replaced, the oil in a normal state .
( 2 ) Check the oil pressure is normal , check the fluid behind the column is invalid.
Remedy:
Check the oil sump pump disassembly , strainer , oil change ; dismantling the valve train, behind the column or valve replacement fluid conduit .

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