Case 521E Loader Service Manual

Table of Contents

• General
• Engine
• Fuel System
• Electrical System
• Steering
• Power Train
• Brakes
• Hydraulics
• Mounted Equipment

Manual Extract: Hydraulic Contamination

Contamination in the hydraulic system is a major cause of the malfunction of hydraulic components.
Contamination is any foreign material in the hydraulic oil. Contamination can enter the hydraulic system in several ways.
1. When you drain the oil or disconnect any line.
2. When you disassemble a component.
3. From normal wear of the hydraulic components.
4. From damaged or worn seals.
5. From a damaged component in the hydraulic system.

All hydraulic systems operate with some contamination. The design of the components in this hydraulic system permits efficient operation with a small amount of contamination. An increase in this amount of contamination can cause problems in the hydraulic system. The following list includes some of these problems.
1. Cylinder rod seals leak.
2. Control valve spools do not return to neutral.
3. Movement of control valve spools is difficult.
4. Hydraulic oil becomes too hot.
5. Pump gears, housing, and other parts wear rapidly.
6. Relief valves or check valves held open by dirt.
7. Quick failure of components that have been repaired.
8. Cycle times are slow; machine does not have enough power.

If your machine has any of these problems, check the hydraulic oil for contamination. See types of contamination below. If you find contamination, use the Portable Filter to clean the hydraulic system.