1. Power steering is heavy or insufficient assist
Fault phenomenon:
The steering is heavy and there is a temporary loss of hydraulic assist.
Cause of failure:
① Oil pump V-belt is loose
② The oil level in the oil storage tank is too low
③ Insufficient oil pump pressure
④ Pressure controlled bonding
⑤ Excessive external leakage
⑥ Internal leakage is too large
⑦ Steering shaft bushing is too tight
⑧ Front suspension deformation
⑨ There is air in the hydraulic system
Troubleshooting:
① Check the condition of the driving part of the steering oil pump. Press down the drive belt of the steering oil pump by hand. If the amount of depression is too large, it means that the drive belt is too tight and needs to be adjusted. Start the engine, run it at idle speed, and suddenly increase the engine speed. Check whether the steering oil pump drive belt is slipping. If there is slipping, the drive belt is too loose or worn and should be adjusted or replaced.
② Check the level of the steering fluid in the reservoir. If the steering fluid level is below the lower line or the "MIN" line, it means that the steering fluid is insufficient and should be added to the specified position.
③ Check the filter in the steering fluid reservoir. Remove the filter and observe the condition of the filter. If the filter is found to be too dirty, it means the filter is clogged and should be cleaned; if the filter is found to be broken, it should be replaced.
④ Check whether there is air in the system. First start the engine and let it run at idle speed, then turn the steering wheel back and forth several times to observe the condition of the steering oil. If foam or oil turbidity is found in the steering oil, it means that air is mixed in the steering system and should be eliminated; check whether the oil inlet pipe of the steering oil pump is ruptured. If it is ruptured, it should be replaced; check whether the pipe joints are loose. If they are loose, they should be tightened; check whether the sealing ring on the steering oil pump shaft is damaged. If there is oil leakage, replace it with a new one.
⑤ Check the oil pressure of the steering system. Connect the pressure gauge between the steering oil pump and the steering booster, keep the engine running at idle speed, and close the pressure gauge valve. If the pressure in 10s does not reach the fixed value, it means that the steering oil pump pressure is insufficient and should be disassembled and inspected for repair. Turn the steering wheel to the left or right limit position and open the pressure gauge valve. If the pressure does not reach the specified value, it means that the steering assistor is faulty or the valve is improperly adjusted. It should be disassembled, inspected and adjusted.
2. Noisy power steering system
Fault phenomenon:
When the car is turning, there is a noise at the steering oil pump.
Cause of failure:
① Oil pump V-belt is loose
② The oil pump bearing is damaged
③ Damage to pressure plate or rotor
④ Excessive wear of oil pump ring
⑤ Insufficient oil storage tank
⑥ There is air in the hydraulic system or the pressure hose is not firmly connected.
⑦ Improper assembly of oil pump
⑧ Relief valve failure
Troubleshooting:
① Check the steering oil level in the oil storage tank. If the level is lower than the lower line or the "MIN" line, it means that the steering oil level is too low and should be added to the specified position. If the steering oil is consumed too quickly, it means there is a serious oil leakage, which should be checked and eliminated.
② Check the condition of the driving part of the steering oil pump. Press down the drive belt of the steering oil pump with your hands. If the amount of pressure is too large, it means that the drive belt is too loose and should be adjusted.
③ Check whether there is air in the steering oil pressure. Open the oil storage tank cover, start the engine and let it run at idle speed, turn the steering wheel back and forth several times, and observe whether there are bubbles in the steering fluid. If there are bubbles, it means that air is mixed in the steering fluid and should be eliminated.
④ Check whether the filter screen of the oil storage tank is blocked and whether the oil pipeline layout is correct. Remove the filter screen of the oil storage pipe. If it is found to be too dirty, it means that the oil circulation is not smooth and should be cleaned. If the oil pipe is bent or dented, it should be replaced.
⑤ If the above inspection results are correct, the steering oil pump should be dismantled and inspected, check whether there are scratches on the blades and the pump body, and replace the corresponding parts according to the disassembly and inspection conditions.
3. Left and right steering have different degrees of severity
Fault phenomenon:
When the car is moving, the left and right steering forces are not equal.
Cause of failure:
① The steering control valve spool (or slide valve) deviates from the middle position, or although it is in the middle position, the size of the gap with the valve body groove shoulder is inconsistent;
② There is dirt blocking the control valve, causing the left and right rotation resistance to be different;
③ Air penetrates into an oil chamber of the power cylinder in the hydraulic system;
④ Oil line leakage
Troubleshooting:
This kind of failure is mostly caused by oil contamination, and new oil should be replaced according to regulations before inspection.
① If the oil quality is good or the fault is not eliminated after replacing with new oil, the hydraulic system should be vented and checked for oil leakage. When a leak occurs in the hydraulic system, the parts at the leaking location should be replaced;
② If the fault still cannot be eliminated, it may be caused by poor centering of the control valve. The spool-type steering control valve can be removed from the outside of the power steering gear by changing the position of the steering control valve body. If the slide valve position still does not improve after adjusting it, the slide valve should be disassembled and inspected to measure its size. If the deviation is large, the slide valve should be replaced. For rotary valve steering control valves, faults must be eliminated through disassembly and inspection.
Source: Auto Repair Case
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