Spectra Watermakers: Troubleshooting Guide - Hybridenergy.com.au

(14) PISTON ROD BINDINGClark Pumps have one or two piston rods which pass through a bore in the Center Block andextend into both cylinders. When the Clark Pump is operating the entering feed water pushesagainst one of the piston which presses on the piston rod. The piston rod in turn transfers thisforce to the opposing piston in the other cylinder, causing it to move. These three parts move asone to the end of the stroke, at which point the driven piston becomes the driving piston and thepistons reverse direction and move to the other ends of the cylinders.Both the bore in the center block through which the rod moves, and the rod itself, are machinedto close tolerances. On rare occasions the rod or center block may swell over time causing therod to bind in the bore. If the feed pressure is excessive and no other cause can be found, thismay be the problem.To determine if the rod is binding one of the cylinders must be removed by loosening the fourlarger Allen screws which hold the cylinder on to the Center block. The cylinder can then bepulled away for the Center Block. The rod should move easily back and forth through theCenter Block.If the rod is difficult to move pull it out of the center block, and then push it back in until it isnot quite touching the lip seal in the bore. The rod should be loose, and have some play. If therod is tight contact a Spectra Distributor or the factory to obtain replacement parts. If the rodmoves easily in the bore the problem may be that the lip seals in the bore are dragging.Replacement seals should be installed if this is the case. Also check to make sure the pistonmoves easily in the cylinder by pushing on it with a hammer handle or similar tool. Be careful,water will squirt out at you when the piston moves. If the piston is tight see 10 Tight PistonsTemporary repairs to oversize piston rods can be made by sanding the rod down with fine gritwet sand paper. Wrap the sand paper around the rod and slide the rod back and forth through itso that you are sanding with the long dimension. Be careful to remove any grit before puttingthe rod back into the bore. When the rod fits easily into the bore, clean it carefully, Grease therod and the inside of the bore with silicon grease if possible and slid it carefully in until it issticking out both sides.5 May 0818HOMEShurflo GuideVane Pump Guide Shurflo MPC Guide