Common Hydraulic Issues in Excavators (and what to do first)

If you park your machine with the boom up and it slowly sinks to the ground, you have drift. This isn’t just a nuisance; it’s a safety hazard. While many assume it’s a cylinder seal issue, it can also be a leak in the main control valve or a failing load-check valve.

A mobile tech can perform a drift test and a cylinder isolation test to determine exactly where the oil is bypassing, preventing unnecessary cylinder repacking.

The swing system is the most used—and often most neglected—part of an excavator. Weak rotation or a “grinding” sound usually means the swing motor or swing gearbox is failing. In Utah’s abrasive dust, the swing bearing seal can also fail, leading to internal contamination.

Early intervention with a gear oil sample and pressure check can prevent a catastrophic failure that requires removing the entire cab and upper structure.

Does your machine veer to one side when tracking straight? This usually points to a mismatch in flow between the two track motors. The culprit could be a failing final drive, a worn center swivel (rotary manifold), or a weak pump section.

Before you condemn a final drive, have a technician check the case drain flow. This simple test tells us how much oil is "escaping" internally. High case drain flow is the smoking gun for a motor that's ready to quit.

The best way to "fix" hydraulic issues is to prevent them. Operators who "slam" the controls and bottom out cylinders under full pressure are the ones who keep mobile mechanics in business. Smooth operation reduces pressure spikes that blow seals and fatigue hoses.

If your operators are noticing changes in machine behavior in Ogden or Provo, listen to them. They spend 10 hours a day in that seat; they know when the machine is "lying" to them. Early reporting saves thousands in repair costs.