Hydraulic Pump Cavitation: Causes & Symptoms

Cavitation is the second leading cause of hydraulic pump failure (behind contamination). Because it can damage the pump and compromise the wider hydraulic system, it’s important to understand what cavitation is, what causes it, and how to spot the symptoms early.

What is cavitation?

Cavitation is caused by excessive vacuum conditions at the hydraulic pump’s inlet. When vacuum is too high, it can create vapour bubbles within the hydraulic oil. These bubbles are carried to the discharge side and then collapse — which is where cavitation damage occurs.

High vacuum conditions are often caused by poor plumbing, flow restrictions, or high oil viscosity. Poor plumbing is commonly linked to incorrectly sized hoses/fittings and/or an indirect (not straight or vertical) path from the pump to the reservoir.

Why cavitation is damaging

Unfortunately cavitation is not where the problem ends. Cavitation can cause:

• Excessive heat
• Violent implosions – when bubbles disperse, material is drawn into the space where the bubble was
• Reduced lubrication – air in the fluid reduces the amount of oil available to lubricate
• Friction and wear – reduced protective oil film allows surfaces to rub and wear

All of these effects can lead to hydraulic pump failure and damage internal components.

What are the symptoms of cavitation?

1) Sound

The easiest way to identify cavitation is through noise. The pump may emit a whining or rattling sound. If you hear either, isolate the pump to confirm the noise source.

2) Metallic debris in the filter

As part of routine maintenance, inspect and replace hydraulic filter elements at intervals based on duty cycle and usage. If you find metallic debris during a filter change, cavitation may be occurring in the pump.

In this case, it’s often best practice to flush the system and detach the pump for closer inspection.

3) Damage to filter elements or components

If you replace a filter and find the element is damaged, cavitation could be a cause. Remove the filter element and inspect for metallic debris. If debris is present, flush the system to reduce the risk of damage elsewhere. Once cavitation is confirmed, you’ll need to determine the root cause.

Need a replacement hydraulic pump?

Hydraulic pumps come in a variety of sizes, styles, and fuel types. If you’re experiencing issues, browse our range for a replacement or get in touch with our team for advice on any hydraulic issue.