Clark 664b bade problems

Treeharvester · November 13, 2020, 06:31:44 AM

So here's what I know, blade slowly drops down when lifted and machine is cold. When the machine is warm it gets to the point you have to drive around pulling on the lift lever the whole time just too keep the blade up. This ends up over heating the hydraulics and making the machine unusable. I rebuilt both the blade hyd cylinders with no change in behaviour. Just wondering if it might be the spool valve or something. I've run out of ideas?!??

grabber green · November 13, 2020, 07:01:40 AM

sounds like your control valve needs repaired or replaced if you have no leaks in your hoses or cylinders. Will your blade hold the machine up when pushed down or will it not load check that way either?

mike_belben · November 13, 2020, 07:17:49 AM

Look at the backcap of the blade spool to be sure that the centering mechanism hasnt broken or come apart. If not it may just be that worn. Either rebuild or replace the valve, or install a pilot operated load check in the blade up workport.

The check will block the fluid that holds the blade up from venting out of the cylinder until it senses pressure from you moving the spool to the blade down position, like a forklift. That unseats the check and opens the path.

Treeharvester · November 13, 2020, 07:42:41 AM

Quote from: grabber green on November 13, 2020, 07:01:40 AM
sounds like your control valve needs repaired or replaced if you have no leaks in your hoses or cylinders. Will your blade hold the machine up when pushed down or will it not load check that way either?

The blade will not lift up the machine at all, the moment it hit the ground that is it. Cold or warm. No external leaks anywhere.

mike_belben · November 13, 2020, 08:33:26 AM

Youve got a low pressure issue too. If the relieve valve isnt bypassing then the valve is either cracked internally, has bad o-rings between sections or is totally spanked. Because the blade drifts down so fast i think its isolated to the valve and not implicating the pump, so far. A bad pump wont cause drift.

kiko · November 13, 2020, 05:43:07 PM

Does the steering work ok? If so I would concentrate on the port reliefs in the blade function. If steering is weak check the main inlet relief. Sometimes the rings are just damaged or blown

Treeharvester · November 13, 2020, 06:46:49 PM

Steering seems fine, or as fine as I'd expect for a machine of its age :D Blade operation is rather slow also. I'm going to remove the valve and bench test it. Seems hard to find parts for it!?
Been calling around with no luck so far.

kiko · November 13, 2020, 07:12:57 PM

IFRC the port reliefs are easily removed with the valve in place. Also I don't believe the valve is machine specific. Probably a Green or commercial valve . Pics may help identify. Still could be obsolete.

Treeharvester · November 13, 2020, 09:08:28 PM

kiko · November 14, 2020, 04:15:24 PM

So that valve is not one I am familiar, different from the d and D series. Still concentrate on the port reliefs for the blade spool.

Treeharvester · November 14, 2020, 10:38:34 PM

Quote from: kiko on November 14, 2020, 04:15:24 PM
So that valve is not one I am familiar, different from the d and D series. Still concentrate on the port reliefs for the blade spool.

Thank you kiko, I will continue working on it and keep you guys updated. Definitely starting with removing the port reliefs. ???

Treeharvester · November 20, 2020, 11:35:25 PM

Took out the control valve and removed all spools and port reliefs. Had some bad orings on the port reliefs. I got all new ones and installed them. Put the valve all back together and installed it. The blade definitely drops a lot slower now but still does drop after awhile. I'm thinking that the port reliefs should be replaced with new ones because the old ones must not be working probably. Think that would be a good next step?!?

mike_belben · November 21, 2020, 07:48:44 AM

Take the cartridge valves apart and look inside at the seats and the pintles that mate into them. Look for signs of erosion, pitting, rust or anything else allowing a bypass. If youve got full strength in the blade circuit, the remaining leakage is probably not the relief.

Lapping compound and a drill works good for freshening up relief seats if you are able to chuck and spin the pintles. Bobcat used some mushroom looking buttons ive had to tap the back side of to do it, but lapping worked fine. The machine sat with no fluid for years and when i got it running it had no travel pressure at all from bypassing around a slightly pitted seat. Runs daily now. Lapping those reliefs will save you probably $400.

Before pulling the cartridge out again.. Raise and lower your blade a few times, then lash it all the way up with a comealong or your winch over the cab or a floor jack and dunnage, hi lift whatever.

Now unhook both blade hoses at the valve and insert jic plugs or caps. Now let the blade down and lets see how much it drifts. Any leakage out of the cylinders is a contributor. This takes the valve out of the equation so you can see how much it is or isnt at fault.

My next suspicion is the valve spool and bore itself being oversized and bypassing. A good shop may still be able to get a OS spool and ream them up.