07-27-2025, 11:15 AM
The Terex 842SS skid steer loader is known for its versatility on jobsites—from grading and material handling to snow removal and light demolition. However, like many compact machines, its performance is only as good as its hydraulic system. When hydraulic issues arise, diagnosing and resolving them requires a blend of mechanical know-how, a methodical approach, and a bit of grit.
Understanding the Hydraulic System in the 842SS
The Terex 842SS relies on a hydrostatic drive and hydraulic circuit to power not only the loader arms and bucket but also the propulsion system. These systems work through a series of hydraulic pumps, valves, cylinders, and motors. Any interruption in pressure or flow can bring the entire machine to a standstill—or worse, cause erratic and unsafe behavior.
The loader features a tandem pump system—typically a charge pump and a high-pressure piston pump. The charge pump feeds oil into the main pump and keeps the system pressurized, while control valves direct the fluid to specific functions.
Common Symptoms of Hydraulic Trouble
Operators experiencing hydraulic problems on the 842SS might encounter:
One equipment technician in Iowa shared a frustrating situation with an 842SS where the loader arms would barely lift under load, but the machine drove fine. After replacing filters and checking fluid levels with no result, they discovered the culprit: a worn-out hydraulic relief valve that was leaking internally. A simple $75 valve fixed what was nearly diagnosed as a full pump failure—a reminder that proper testing saves money.
Step-by-Step Troubleshooting Process
Hydraulic failures are not just inconvenient—they can be dangerous. Unexpected boom drops or uncontrolled movement risk injury or damage. In one 2020 incident in Alberta, a skid steer with a sticking valve dropped its boom onto a trailer ramp while being loaded, damaging both the machine and the ramp. Fortunately, no one was injured, but the cause was traced to debris in a control valve.
Always depressurize the system before working on it, and ensure lockout procedures are followed.
When to Rebuild or Replace Components
Hydraulic components have lifespans, especially pumps and cylinders. If a pump is weak, rebuilding may be cost-effective if the housing and gears are intact. However, in machines used heavily in dust or extreme cold, replacement is sometimes the better choice due to wear on internal tolerances.
One mechanic noted that many skid steers, including the 842SS, suffer from premature valve body wear due to infrequent hydraulic fluid changes—highlighting the need for preventive maintenance.
Final Thoughts: Respect the Flow
Hydraulic issues can be a major headache, especially on machines like the Terex 842SS where space is tight and components are packed in. But with the right approach—start simple, measure pressures, follow fluid paths—many problems can be resolved without major expense.
In the words of one seasoned operator: “When the machine talks to you, listen. That whine or that hesitation isn’t just annoying—it’s telling you something.”
Hydraulics may be a hidden force beneath the steel and horsepower of heavy equipment, but they’re also the lifeblood of performance. And knowing how to keep that lifeblood flowing is what separates good mechanics from great ones.
Understanding the Hydraulic System in the 842SS
The Terex 842SS relies on a hydrostatic drive and hydraulic circuit to power not only the loader arms and bucket but also the propulsion system. These systems work through a series of hydraulic pumps, valves, cylinders, and motors. Any interruption in pressure or flow can bring the entire machine to a standstill—or worse, cause erratic and unsafe behavior.
The loader features a tandem pump system—typically a charge pump and a high-pressure piston pump. The charge pump feeds oil into the main pump and keeps the system pressurized, while control valves direct the fluid to specific functions.
Common Symptoms of Hydraulic Trouble
Operators experiencing hydraulic problems on the 842SS might encounter:
- Slow or Jerky Loader Arm Movement: Suggests low flow or pressure loss.
- No Movement in One or More Functions: Could point to a stuck valve, clogged filter, or pump failure.
- Overheating Hydraulic Fluid: Indicates fluid is bypassing internally or a cooling failure.
- High-pitched Whining Sounds: Often a sign of cavitation or air in the lines.
- Unresponsive Controls: Could mean electrical failure in solenoids or low voltage to valves.
One equipment technician in Iowa shared a frustrating situation with an 842SS where the loader arms would barely lift under load, but the machine drove fine. After replacing filters and checking fluid levels with no result, they discovered the culprit: a worn-out hydraulic relief valve that was leaking internally. A simple $75 valve fixed what was nearly diagnosed as a full pump failure—a reminder that proper testing saves money.
Step-by-Step Troubleshooting Process
- Check Hydraulic Fluid Level and Condition: Low or contaminated fluid is a leading cause of system failure. Look for milky appearance (water) or burnt smell (overheating).
- Inspect Filters and Screens: Clogged filters restrict flow and cause pressure spikes or starvation.
- Test Pressure at Key Points: Use gauges to check pressure at loader valve, motor, and pump output. Compare against factory specs.
- Examine Hoses and Fittings for Leaks or Damage: A cracked hose may not visibly leak under low pressure but fail under load.
- Evaluate the Charge Pump: A weak or failed charge pump means the main pump can’t build pressure. Many overlook this small but vital component.
- Inspect Control Valves and Linkages: Mechanical linkages can wear or break, especially on older machines or those stored outside.
- Electrical Components: Solenoids or pressure switches may fail silently, especially if exposed to moisture or vibration over time.
Hydraulic failures are not just inconvenient—they can be dangerous. Unexpected boom drops or uncontrolled movement risk injury or damage. In one 2020 incident in Alberta, a skid steer with a sticking valve dropped its boom onto a trailer ramp while being loaded, damaging both the machine and the ramp. Fortunately, no one was injured, but the cause was traced to debris in a control valve.
Always depressurize the system before working on it, and ensure lockout procedures are followed.
When to Rebuild or Replace Components
Hydraulic components have lifespans, especially pumps and cylinders. If a pump is weak, rebuilding may be cost-effective if the housing and gears are intact. However, in machines used heavily in dust or extreme cold, replacement is sometimes the better choice due to wear on internal tolerances.
One mechanic noted that many skid steers, including the 842SS, suffer from premature valve body wear due to infrequent hydraulic fluid changes—highlighting the need for preventive maintenance.
Final Thoughts: Respect the Flow
Hydraulic issues can be a major headache, especially on machines like the Terex 842SS where space is tight and components are packed in. But with the right approach—start simple, measure pressures, follow fluid paths—many problems can be resolved without major expense.
In the words of one seasoned operator: “When the machine talks to you, listen. That whine or that hesitation isn’t just annoying—it’s telling you something.”
Hydraulics may be a hidden force beneath the steel and horsepower of heavy equipment, but they’re also the lifeblood of performance. And knowing how to keep that lifeblood flowing is what separates good mechanics from great ones.
