A Shanghai Santana GLI sedan, the cumulative driving 12.2 million km, the engine in the idle operation, turned to the power pump issued a "buzzing" sound, when the left and right turn the steering wheel when the abnormal increase. The car in a month to replace the two steering pump, put the first steering pump to use when the use of about 20 days of noise will appear, the first two only 7 days the same problem will appear again. According to the maintenance of technical personnel, they purchase channels of formal, this accessories have sold more than one, have not appeared similar problems.
    After the demolition of the pump has been changed, no abnormal wear. The car stopped at the flat road, through a comprehensive visual inspection found that hydraulic piping, pump and the direction of the machine without oil leakage phenomenon, the tank of hydraulic oil between the upper and lower limits, the belt elastic moderate, but the hydraulic oil There is a degeneration of black (Figure 1). Through the test found, turn around the steering wheel, steering force normal, in the steering to the stable and flexible, did not appear when the steering deviation, heavy and hair floating phenomenon, and turned back to good.
    Is it really the noise generated by abnormal wear in the pump? According to the owner to put on a new pump, never found the phenomenon of oil spill. And this pump only used less than 10 days, should not be due to wear within the pump. If the pressure inside the pump pressure valve is too poor, the pressure will be too low, the performance of the steering heavy; if the pressure is too high, because the power cylinder left and right pressure is too large, driving will appear in the direction of automatic deviation; if the steering distribution The valve is poor or internal leakage, there will be heavy steering; if the steering distribution valve stuck, will lead to poor return position; if the distribution of spool and valve sleeve with poor clearance, there will be deviation and hair phenomenon. After the above test and analysis, apparently does not meet any of the above conditions, it seems that the various parts of the system work well, there is no adverse wear and tear phenomenon.