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Working With Excavator Hydraulic Pump Issues? Do These Quick Tests & Checks First Before Replacement,
- Grayson Fleming
- 23 hours ago
- 2 min read
The main hydraulic pump is one of the most commonly mis-diagnosed components on John Deere & Hitachi Excavators. All hydraulic functionality depends on the integrity of the pump device, making it logical to tie issues back to the main hydraulic pump. However, not all excavator hydraulic pump issues here, and some basic testing can be worthwhile to determine if replacement is actually required
First, lets talk about the tell-tale signs that lead us to question the pump and what could cause them. These include abnormal noise, chattering, cavitation or slow or weak functions. When dealing with abnormal noise, and hydraulic oil level is confirmed to be correct, these are a few quick items to over:
Check hydraulic filters for any abnormality or restriction - look for any foreign material such as brass, steel, or packings, or even collapsed elements.
Verify the hydraulic tank breather check valve is operating correctly. A faulty check valve can cause abnormal pump noise under load.
Remove bleed plugs to check for air in the pump housing. Locations for these bleed plugs can vary, but they will always be found at the top of the pump or regulator housings, usually marked in a distinct color. (Red, green, etc.) If air becomes trapped in the pump housing, it will rarely work itself out and can cause cavitation and less than desirable noises. Running on steep side slopes, low hydraulic oil levels, or even hydraulic oil replacement without following the correct bleed procedure can all allow air to enter the pump. All air must be removed for proper operation and to ensure good health of the hydraulic system.
You've completed the basic checks, but the issue remains. These are a few common issues pointing towards a weak pump device. As a pump wears, it is common for perfomance & noise issues to become more noticeable, especially when the machine / hydraulic temperature is warm, or functions are under load. Mis-tracking, or slow & weak functions are also common and most noticeable. At this point, a proper flow test and quick check on pressure readings will shed more light onto the pumps health.
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