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 wha