I have 2 46z serial number machines that once loaded wont lift their bowls. We have replaced cables to the bowl control levers, new hydrualic pumps, and rebuilt the valve spools. Cables are within adjustment and we are getting full throw on the valves. At a loss so any ideas would be great. Thanks in advance!
Have you checked the bowl lift cylinders? Those packings are usually the culprit, either one cylinder or both.
We did replace one lift cylinder too, and the other is weeping. Actually both machines have a cylinder weeping, so Ill dive into it this morning. Appreciate it.
Had it happen to me on a 627 . A piece of o ring was stuck it pressure relief..
Off of the lift cylinder your saying?
Try raising the scraper bowl for an extended period of time when the machine fluids are cold - say a couple of minutes. Carefully touch the bowl cylinder barrels. Is one of them warm around the location where the piston ought to be, or maybe both.? If that's the case you've found your culprit - leaking cylinder piston seals.
Got it nipped, the new pump on one of them wasnt working. Took care of one and pressure relief on the other. Thanks guys.
How would the leaking oil heat the cylinder where the piston is?
Thanks for letting us know what the culprit was. It cleans the post up nicely and may help someone in the future. Well done.
The high pressure oil leaking past the piston very quickly heats that spot. To find which cylinder is leaking past the piston om a dual cylinder system we have restrained the lift cylinders at midpoint and the leaker is soon found. Often saves pulling the wrong side down.
Pressure 1 on one side of cylinder is high. P2 is at tank pressure. When the oils leaks by, it is losing all that energy. It will heat the pistons and cylinder. I can 100% confirm this in a few documented cases. One of which is a ag implement. Has to work way harder than it should to lift. After 15min of work, one cylinder certainly stands out in temperature. That is all I need for confirmation!
Not unlike when oil flows over the relief setting. It’s bypassing just the same.
Because of oil passing over the piston/seals
Because if the piston seals are leaking oil will be forced at high pressure through a very small space between the seals and the cylinder barrel. That will create heat - loads of it. Thermal imaging cameras are wonderful for picking up leaking cylinder piston seals.