Spool valve stuck, flush hyd lines or not?

[MG84]

Tried the return line filter plumbed in the circuit today, was basically a failure. First filter exploded, fluid was too cold and I tried to pump it though too fast. Warmed the fluid up and ran it slower, second filter ran for an hour and seemed to do nothing.

Tomorrow I'm going to start the arduous process of disassembling everything and try the foam projectiles. I'm going to see what I can find at Lowes/Home Depot/HF that I could make some out of, don't have the time to wait to buy them and have them shipped, not to mention the 'kits' are ridiculously expensive for what I need. I think the foam is about the density of a pool noodle, or foam pipe insulation, I'll see what I can find. I'll have to make a plug cutter, I think a sharpened piece of pipe/tube would work. Dimensions I see online say plug needs to be about 20% larger than the diameter of the pipe.

 

[terex herder]

I don't know how much it matters, but I think the hose cleaners are a much finer porosity foam than the cheap foam like pool noodles.

 

[Welder Dave]

See if you can rent a proper filter cart from a hyd. shop. Taking all the hoses off and reconnecting them is just as likely to introduce contamination and leaks as it is to fix your problem.

 

[HarleyHappy]

Use foam ear plugs, seems to be the same density.

 

[MG84]

It's fixed, sort of, for now anyways lol.

Found some 1/2" Foam Backer Rod at Lowe's that made excellent plugs, just cut off a piece 3/4-1" long and its ready to go. They were a good snug fit in the 1/2 metal lines, hoses and fittings, and actually made it around 90* fittings. Blew the hyd oil out with air first, then blew 5 plugs through each hose. Disassembled the spool valve as far as I could without removing it from the machine, took out the spool, load checks and fittings, which basically gave me access to every passage in that valve block. Cleaned everything well with brake clean, compressed air and some little brass bore brushes. I'm confident that the hyd circuit is completely clean of debris now.

Put everything back together, and the valve stuck the first time I tilted the blade to the right. I've determined the problem now isn't debris but something wrong with the spool or valve block itself. There was a little nick in the spool previously that I filed smooth and the valve works fine before you pressurize it (moves easy by hand), but once you apply fluid pressure in that one direction it locks up. In disgust I took a large drift punch and hammer and beat the spool down, then cycled it dozens of times, I think it self clearanced because it works now. I know the valve section is damaged now but I'm going to just run it and see what happens, so far it seems to be working. In the meanwhile I'll see if I can track down a complete valve assembly, to replace the bad section and also give me another to add rear remotes.

 

[Mechanicsville804]

It's fixed, sort of, for now anyways lol.

Found some 1/2" Foam Backer Rod at Lowe's that made excellent plugs, just cut off a piece 3/4-1" long and its ready to go. They were a good snug fit in the 1/2 metal lines, hoses and fittings, and actually made it around 90* fittings. Blew the hyd oil out with air first, then blew 5 plugs through each hose. Disassembled the spool valve as far as I could without removing it from the machine, took out the spool, load checks and fittings, which basically gave me access to every passage in that valve block. Cleaned everything well with brake clean, compressed air and some little brass bore brushes. I'm confident that the hyd circuit is completely clean of debris now.

Put everything back together, and the valve stuck the first time I tilted the blade to the right. I've determined the problem now isn't debris but something wrong with the spool or valve block itself. There was a little nick in the spool previously that I filed smooth and the valve works fine before you pressurize it (moves easy by hand), but once you apply fluid pressure in that one direction it locks up. In disgust I took a large drift punch and hammer and beat the spool down, then cycled it dozens of times, I think it self clearanced because it works now. I know the valve section is damaged now but I'm going to just run it and see what happens, so far it seems to be working. In the meanwhile I'll see if I can track down a complete valve assembly, to replace the bad section and also give me another to add rear remotes.

Recently I experienced the same situation on our Backhoe, I removed the spool and I ran a sandpaper flapper disk (like you would see on a drimall tool) up an down the valve body till I felt the nic in the valve body was gone. The same nic in the spool with be in the valvebody. I finished off with heavy brake clean to remove all of the debris I made and reassembled, Praise God, everything went well. Hope this will help you.

 

[Welder Dave]

I wonder if a small brake cylinder hone would work on a hyd. valve? They aren't expensive and go down to 3/4" I think.

 

[Roadoil]

Depending on the direction valve there may be O rings used on the spool. They can cause issues.

Other than that the piston maybe be fine but you may have a bad bore time to replace direction valve.