Clark C500 SERIES:
C500 S30 Intermittent Mast Lift Problem Diagnosis

235-27-2202 This is my first forklift, prior owner used it in this condition for a few years. It has a three stage mast. Issue is this: Tilt works properly, feels strong. Side shift has be disabled because of leaking/removed cylinder but I am not sure how. Aux valve and lever remain. Lift cylinder barely creeps up a few inches with lift lever only. If I hold side-shift lever either way, I can feel pressure build and then using mast lever, the mast lifts properly and has good "speed" and "hold", lowers smoothly. I can do the same using the tilt, get it to its stop, feel pressure build, hold it there, then mast works using mast lift lever. This has been the technique used for few years without further problems. Is there a specific hold or check valve I should be zeroing in on? Could it be related to the decommissioned side-shift? Thanks in advance.
  • Posted 5 Jul 2018 01:09
  • Discussion started by Gordon
  • Illinois, United States
Showing items 1 - 4 of 4 results.
Problem solved! This is an older model with a combined tilt/lift lever on the steering column. That means there is a lot of linkage and a bellcrank. One bracket had move creating excessive slop in the lift portion of the mecanism. My previous efforts were not fully moving the spool. I guess the increased line pressure cause the spool to fully engage. I adjusted the linkage and it works great. This remote mounting of the valve with extensive linkage was abandoned several years ago for good reason.
  • Posted 7 Jul 2018 21:39
  • Reply by Gordon
  • Illinois, United States
I think under the fitting on the main valve where the hose is attached that goes to to aux valve. Take the fitting out and look in there. I will try to look at one tomorrow, it's been a long time since I did a aux valve addition on one of those.
  • Posted 6 Jul 2018 05:33
  • Reply by mrfixit
  • New York, United States
I am not a the location of the forklift now, but do have the parts manual that has line routing graphics. The main valve return line has a tee in it. The return line from the Aux Valve connects to this tee. There is a pressure line from the main valve to the Aux valve. I am uncertain what you mean by "plug under the fitting, where the hose is". Which hose am I looking under? Thanks
  • Posted 5 Jul 2018 21:03
  • Reply by Gordon
  • Illinois, United States
I think maybe I can help. First, how is that plumbed, is there a hose from where the return line on the lift/tilt valve was to the separate aux valve? I recall there is a plug under the fitting, where the hose is, on the lift/tilt valve that was either installed or removed when you set one of them up for a separate aux valve.
  • Posted 5 Jul 2018 09:38
  • Reply by mrfixit
  • New York, United States

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