Volkswagen steering booster pump has abnormal symptoms
A 1997 Shanghai Santana GLI sedan with a total of 122,000 km on the odometer has been experiencing an unusual humming noise from the power steering pump. The sound becomes more noticeable when turning the steering wheel left or right. The car owner replaced the power steering pump twice within a month—first after about 20 days and then again after just seven days—but the same issue persisted. According to the service technicians, the replacement parts were sourced through official channels, and they had not encountered similar problems with this component before.
After removing the faulty pump, no signs of wear or damage were found. The vehicle was parked on flat ground, and a thorough visual inspection revealed no oil leaks in the hydraulic lines, pump body, or steering gear. The hydraulic fluid level was within the normal range, and the drive belt was properly tensioned. However, the hydraulic oil showed signs of degradation and was quite dirty.
During testing, the steering wheel turned smoothly, with no issues such as heavy steering, drifting, or lack of return. The system felt responsive and stable. Despite this, the noise remained. The question arose: was the noise truly caused by internal wear of the pump? The pump had only been used for less than 10 days, so internal wear seemed unlikely. If the pressure relief valve or flow control valve were faulty, it could cause heavy steering or unintended direction changes. A malfunctioning distribution valve might result in poor steering return or instability. However, all these conditions were ruled out during testing.
The only anomaly found during the inspection was the deteriorated and contaminated hydraulic fluid. When the engine was idling and the steering wheel was turned several times, the hydraulic oil temperature rose to around 80°C. After removing the reservoir cap and observing the oil surface, bubbles were seen rising intermittently. This raised the possibility that air bubbles in the hydraulic fluid were entering the pump, causing aerodynamic noise. But why were there bubbles?
Further analysis revealed that the issue stemmed from a clogged filter cartridge. A blocked filter can create excessive pressure differential across it, leading to unstable oil flow. When the oil level fluctuates, the negative pressure on one side can draw air into the system, which then gets compressed in the pump, creating the humming sound.
Replacing the filter and thoroughly cleaning the hydraulic system, followed by refilling with clean, standard hydraulic fluid, resolved the issue completely. The abnormal noise disappeared, and the steering functioned normally.
In Volkswagen vehicles, a damaged or misaligned filter can also cause similar noises. The filter serves two main purposes: filtering contaminants and stabilizing oil flow to prevent air bubbles from forming. Therefore, whenever a power steering pump produces strange noises, checking the condition of the filter and the quality of the hydraulic fluid is essential. It’s a simple but crucial step that can save time and avoid unnecessary part replacements.
Aluminum Standard Profiles,Aluminum Louver Profile,Aluminum Alloy Profiles,Extruded Aluminum Profile,Standard Aluminium Extrusions
GUANGDONG YONGLONG ALUMINUM CO.,LTD , https://www.yonglongaluminium.com