Symptoms: There is a B4 Passat sedan steering pump ring, the direction of rotation, the starting car has a "whining" sound, hit the steering wheel noise increased. Troubleshooting: 95 B4 Passat steering pump is driven by the engine rotor vane pump, when not steering, the steering valve to maintain the open state, the steering cylinder on both sides of the work chamber and the low-pressure return pipe connected and ineffective, Steering impeller pump output of oil through the steering distribution valve back to the steering oil storage tank. Due to steering pressure and flow restriction valve throttling resistance is very small, so the impeller pump output pressure is very low, the steering wheel is set after the impeller pump is actually idle state. When steering, the steering cylinder in the corresponding working chamber and the return line disconnected at this time with the impeller pump output pipeline connected to the other while the booster cylinder is still open back to the oil pipeline, the formation of steering than the distribution valve section Flow resistance impeller pump output pipe resistance is much higher, so that through the impeller pump, a certain pressure of the fluid, driven by the distribution valve to promote the role of the rack gear. From the above mechanism is not difficult to see that the steering wheel is square, the starting car has a "whining" sound, playing direction increased, and to be sure, the higher the engine speed, the louder the greater the steering wheel angle, the more powerful the sound . The reasons for this phenomenon, mainly in the following areas: ①back to the oil pipe or steering blocked, back to the oil pressure is too high. ② steering pump bearing damage. ③ with oil pan or rotor damage. Stator excessive wear. ⑤ pressure and flow control valve problems. As for the pump can not be maintained for how long? This steering pump should be carefully examined to determine what is the cause of the pump. In the case of tubing or other components and steering, troubleshooting of other components should be performed without having to replace the steering pump. If it is bearing abnormal sound, the stator wear or rotor damage should be promptly replaced. If necessary, the pressure test, pick the table measurement, basically to determine the degree of damage within the pump, the car up, hear or feel under the car to increase the sound load, and manometry in the standard range, do not change the pump Still can run a long distance should be no problem, the pressure standard is 7.2-8.4MPa (90-105Bar), if the pressure is low, the direction of Shen timely replacement or repair, so as not to cause damage to the steering machine or other components, it is important to ensure traffic safety .