Backhoe problem

[runningbird]

My boom will not stay up. Tried switchin hoses around to see if it might be the control valve, but no change. Would this indicate that the cylinder has a problem? Thanks for any help.

 

[ray66v]

If the piston in the cylinder is extending when it comes down, it could be the cylinder.

How long does it take to come down?

 

[runningbird]

No more than 3 sec

 

[runningbird]

The cylinder is contracted when the boom is up. It extends when dropping down.

 

[ray66v]

Here is how I was taught to check the cylinder:

If it's not too difficult to do, I would remove the cylinder. Push the piston in all the way, and fill it with oil. Then, cap the threads where the hoses go. They are generally NPT threads. So, you can use pipe plugs.

Put the fixed end in a vice, or secure it in some way, and put a long screw driver, or rod through the other end of the piston, and see if you can pull the piston out.

If it only moves a little bit, and resists pulling all the way out, the seal is okay.

If it's leaking that bad, it should pull all they way out pretty easily.

If that's the case, you could start by inspecting the piston for defects, and replace the seals in the cylinder.

 

[Leejohn]

If you can safely remove one end of the cyl, then lets say the piston end. Put pressure on it and run the rod all the way out. Remove the rod end hose then put pressure to the base end, if oil comes out the rod end port you have bad piston seals.

 

[runningbird]

Thanks for the help, I'll check it out today.

 

[runningbird]

had a bad seal on the piston. waiting for parts now.

 

[ray66v]

Good luck with your repair.