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Message: <blockquote data-quote="mllud" data-source="post: 20381" data-attributes="member: 1012">This is a recent post of Kens on tilt cylinders. I think this is what Tazza is talking about.Cylinder bypassing the piston internally? The test, unhook the hoses, push the rod in and out to remove most of the oil. Plug the port on the barrel end of the cylinder, and take the pin out of the rod end, hook your air compressor to the port on the rod end and pressurize it. If the packings are good the rod will retract into the cylinder and STAY there. If the cylinder is bypassing, the rod will retract then begin to extend itself. As the air bypasses the piston it moves from the rod side that has a smaller piston area to the backside, since the piston has more area on the back side (becasue the chrome rod is eating up the usuaable area) and the back port is plugged the pressure equalizes on both sides of the piston but the back has more area so the rod extends out of the barrelIf the cylinder passes this test then its your load check (unless you have a external leak)Ken<table style='width: 100%'><tr><td> <table style='width: 100%'><tr><td>Re: 763 lift arms won't stay up Posted: 12/11/2008 02:58 PM</td></tr><tr><td>The piston seals on one or both of your lift cylinders is leaking past, or it can be the control valve the foot pedal attaches too. You can pressure test the seals on the cylinder piston with compressed air and see if they are sealed or bypassing the piston and escaping out the opposite port on the barrel. If the pistons are sealing. then hook a 3000 psi pressure guage to the hose that goes to the back end of the cylinder and plug the hose going to the opposite side of the machine on the back end of that cylinder. Start the machine and push the pedal to lift the boom. The guage pressure should rise (the boom should not lift if you hooked into the right hose and plugged the other one) to about 2250 to 2500 psi and stay near there when you release the pedal. If the pressure drops back down to 0  you have a problemwith a internal leak in the control valve or a bad hose. (the hose is unlikely because you would notice the oil leaking out everywhere) Ken</td></tr></table></td></tr></table></blockquote>

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