Detection and diagnosis of low pressure of engine cylinder

Category:Automobile engine repair - Date:2016-02-20


main factors causing low engine cylinder pressure.
the main factors of low engine cylinder pressure are as follows:
(1) metal parts wear naturally due to friction at high temperature, resulting in increased gap between piston and cylinder and poor sealing.
(2) the acid of the burning gas is corroded to the cylinder wall, the mechanical impurity in the dust, the fuel and the oil in the air and the incomplete combustion of the coke, and the abnormal wear of the piston, the piston ring and the cylinder is badly sealed.
(3) the piston ring card is dead in the ring groove, the carbon is too much, can not be flexibly rotated, work bad, when inhaling the mixture air pressure shrinkage, through the gap leakage of the crankcase.
(4) valve clearance is incorrect (or misaligned), intake and exhaust valves can not be opened and closed according to the prescribed time, so air intake is insufficient, exhaust gas is not exhausted, and power is insufficient.
(5) the valve seal is bad, the valve is ablated, the engine is leaking when the engine is compressed, and the necessary compression pressure can not be set up, so the engine will feel the power is insufficient.
(6) the cylinder liner ablation, the plane deformation of the cylinder head and the torsion of the cylinder head screw are not enough (or loose), which will cause air leakage and the pressure inside the cylinder is insufficient.

Low engine cylinder pressure



Method of measuring cylinder pressure
When the cylinder pressure is detected, the cylinder pressure meter is installed on the engine, then the starting switch is connected, the starter, the engine running (but not working), and the pressure gauge pointer reaches the maximum stability value, and the compression pressure value is read. Press the check button to carry out the depressurization of the exhaust. 2 times per cylinder, it is appropriate to take its average value.

Detection and judgment of low pressure of engine cylinder

(1) the pressure of each cylinder is generally lower than the prescribed value:
for each cylinder valve leakage or cylinder wear, piston clearance is too large and piston ring wear and other poor sealing.

(2) the pressure of individual cylinder is too low:
may be the cylinder valve burning or cylinder gasket erosion and gas leakage.

(3) when the adjacent two cylinders have low pressure, but they are basically the same, they can be diagnosed as two cylinder cylinder gasket erosion and cylinder connection.

(4) although the cylinder pressure is not obviously low, but the cylinder pressure rises slowly. When the starter rotates for a long time, the pressure can barely reach the average value.

in this case, it can be diagnosed that the intake manifold gasket of the cylinder has air leakage.

the above is the vehicle maintenance technology network / self summary summary, please indicate the source, thank you.

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