This is hard to explain to I will do my best. When pilot controls in neutral boom and bucket will drift till resting on ground. Stick and Aux circuit do not drift. takes about 3 to 5 seconds from 6 feet of ground. doesn't matter if pilot shut off is on or off. If I stall out bucket curl, boom will start to rise very slowly. Checked filters and no contamination. My thinking is it may be in the pilot manifold or in the pilot controller. Any thoughts. I'm also going to try some pressure tests and see. This unit is old and has been neglected for a while. Unknown as to how long the problem has ben there.
Have you tried switching over pattern controller .does problem switch sides ?
doesn't have a pattern controller. if it does unknown to where it is, had a look and cant seem to find it.
Good one, this ought to take awhile.
Valve to spool clearance is too high. Theory proven when the boom raises when the bucket is stalled. Bucket is stalled, pump is at max pressure. That high pressure is leaking into the boom circuit and by default the piston area is greater producing more force extending the cylinder. Greater pressure -> more potential for leakage. Not sure what kind of load holding devices are in the valve block of this unit to explain why it would drift in neutral. Did you just purchase the machine? You may be able to send the valve block out and have it honed and the spools plated and ground
Well, that would definitely be easy to prove. Remove boom control pilot lines at the main spool, cap, and recheck. Boom moves, problem solved(well, sort of). Boom stays put, problem still out there.
thanks give those a try. And I'm going to check the spools and springs.
If you boom down with the bucket bottom at about 45 degrees, teeth in the ground and the stick pretty much straight down, does it hold the machine up, or does it drift in that direction also? I'm thinking the first thing you need to do is repack the cylinders, then check the main spools and port reliefs/checks, then maybe last the pilot controls, since it's drifting with the pilot shutoff engaged.
Found the problem, checked the control valve spools, boom cylinders. I capped of boom pilot hoses hose on the control valve and it stopped drifting. Then hooked back up and started again. remove the boom pilot hose before the pilot manifold and capped it of and it stopped. hooked back up and started drifting. The only other common valve between the boom and bucket was the pilot control valve in the cab. Replaced with a new one and it stopped drifting with everything hooked up. Must be a common problem considering that the dealer Wajax had then on the shelf. Thanks for all the ideas and help. It made it a lot quicker for troubleshooting.