hi all hoping to get some advice from anyone here. i have a hitachi ex600H-5 exacavator ive been working on. all of the controls are sluggish/slow. they respond quickly to contol lever but in general all movements are slow (bucket,stick,boom, swing,track drives, etcc...) ive replaced all hydraulic filters (main, suction and pilot) found sluggy/slimey stuff stuck to suction and pilot filter, the pilot filter actually had a hole blown out the side of it. ive tested primary pilot pressures off the outlet side of pilot filter. pressure spec is 568.9 psi (high and low idle) but i am only getting 420 psi at low idle and 440 psi at high idle all through different modes (econmy ,super power, auto idle, or work modes) also to note that it is not throwing any type of codes or lights on dash. recent repairs that have been done on machine is specifically the oil cooler. we had the core of oil cooler repaired as it got damaged and leaked fluid everywhere. during that repair we drained all the hydraulic fluid out of the tank. the hydraulic fluid was also water contaminated, so i wiped the tank dry, cylinders still had orignal fluid. after repairs were made and oil cooler was reinstalled and fresh fluid was put back in (was a cheaper oil ridgeline brand hydraulic oil) we ran and tested machine functions were good controls moved correctly and smoothly. then the machine sat for 6-8 months before being used again and we noticed now we have sluggish/slow controls. another symptom found was our aftermarket bucket wedge does not work when button is pressed, i have to bottom out a cylinder and hold it to make the cylinder push the wedge out. any advice helps
Welcome to HEF popkum . Check the pilot pressure relief valve for debris. Did you jump the diagnostic connector to check for any service codes ? Procedure below. .
You have multiple interconnected issues stemming from that water contamination and long sit period - this isn't a single-fix problem. Primary culprit: Contamination + cheap oil + sitting = varnish/sludge buildup The sludge on filters and blown pilot filter tell the story: Water contamination mixed with lower-quality oil created varnish deposits throughout the system 6-8 months sitting allowed it to gel/solidify on valve spools, compensators, and orifices Your low pilot pressure (420-440 vs 568 psi spec) confirms pilot relief valve is stuck or pilot pump is worn from contamination Why everything is slow: Varnished valve spools: Sticking, not stroking fully = restricted flow Pump compensators gummed up: Can't respond to load sensing properly LS system clogged: Orifices and shuttle valves partially blocked = poor flow distribution Pilot pressure low: Insufficient signal to fully command main spools Aftermarket wedge issue: Confirms low system pressure/flow - needs full pressure to overcome spring/load. fix: Drain and flush system properly with flushing fluid or quality hydraulic oil—that Ridgeline oil may be part of the problem Replace with OEM-spec hydraulic fluid (ISO 46 or as specified) - don't cheap out Clean/replace pilot relief valve - your 420psi reading screams stuck relief or worn pilot pump Disassemble and clean main control valve - varnish on spools is killing response Check main pump compensators - may need teardown/cleaning This is beyond filters. Half-measures will leave you chasing symptoms.
thanks for the reply unfortunatly we do not have a HD scanner for our equiptment. but on that note if there was a code a light would be flashing on the monitor correct? will definetly be checking pilot relief valve for debris
thank you for the detailed reply will defenitly take all information into consideration. really appreciate the response!
On the EX600H-5 ,there is no service code light installed on the monitor to indicate any code or issues. In post # 2 , I gave the procedure in the (2) screenshots on how to access service codes without a computer/ scanner.
ah misread your post. thought with the scanner this is WITHOUT scanner as its underlined haha will defenitly be trying this thank you for the post!