No hydraulics on a Case 621

[willie59]

ATCO - you deserve some kind of prize for that novel ! :notworthy

Just wanted to clarify - pressure at the line to pilot valves has to be there as long as the engine is running, as it should get pressure from loader section of pump - if no pressure, problem exists in pressure reducing valve or shuttle valves.
It has got me stumped why it loader doesn't react when pressure is delivered from steering relief....... I feel your pain tightgtp :Banghead

LoL...aww, somtimes I get a wild hair and type all manner of BS.


That's correct about the work equipment pump delivering pressure to the pilot circuit during normal operation. I just suggested blocking that supply earlier to simplify things, as we are certain we can apply pressure to the regulating valve by dead heading steering and popping steer relief, that means we know pressure is againt regulating valve at that point, and shuttle check valves are now out of the troubleshooting process.

 

[maytag]

maybe some help

I feel the your pain also-first I'm not a heavy equipment mechanic-I'm an industrial mechanic and a hydraulic tech. Mobile circuits are somewhat different but the physics is the same regardless of the prime mover.
Looking at the flow chart some one posted-if your accumulator has a drain or a relief in parallel(most all industrial accumulators are set up this way) and the drain or relief has opened you could lose your pilot pressure via this path back to tank. If it was possible I'd take a direct operated valve(log splitter type) and connect to a function and see if either the lift or tilt would work correctly.
This would tell you whether the main pump was good. a schematic would be most helpful.

Hope some of this helps,
Tom

 

[tightgtp]

ok so i was finally successful yesterday. after i changed the bad check valves, which were completely disintegrated, i still could not get the hydraulics to work. so at that point i swapped the main relief in the control valve with a known good one. still i could not get the unit to work, so i put the old one back in. at that point i replaced the hydraulic pump. then the headaches began. after all the troubleshooting i came back to the relief valve, come to find out the plunger inside had gotten chewed up and there wasn't much left. so the combination of the check valves and the hyd pump going bad took out the relief valve. so after flushing as much of the system as i could and replacing the relief valve and all is well again.

 

[maytag]

Glad you got your problem resolved-where in Illinois are you located?

Tom

 

[tightgtp]

near rockford

 

[maytag]

Not that it makes any difference I thought you might be from southern IL,
I'm from far western KY but have been gone for several years. Glad you got your problem taken care of, don't envy the mobile hydraulic tech's job-much easier to diagnose and repair industrial hydraulics.

Tom