Do you need to purge air out of the hydraulics?

[Dedaisy]

I've just repaired a piston on my tractor's loader wondered if I needed to purge the air out before reinstalling? and just how do you do it?

 

[J_J]

Just cycle the cylinders through several times. The air will be forced out.

 

[oldnslo]

I've just repaired a piston on my tractor's loader wondered if I needed to purge the air out before reinstalling? and just how do you do it?

On a loader you typically do not have to purge the air from a cylinder. Normal procedure by most people is to install the cylinder and then cycle it through its full range of motion several times. Be sure to check your oil level after doing this. Depending on the cylinder size it could take 1/2 gallon or more to fill it.

If you want to try and bleed the air out before connecting the lines you should have a helper that you trust.

What I do is have the cylinder fully retracted.
Connect the hose to the cap end of the cylinder.
Plug the hose that goes to the rod end to prevent oil from coming out.
Using the tractor hydraulics slowly extend the cylinder fully while watching so that it doesn't catch or bind on anything.

With the cylinder fully extended shut the tractor off and release any pressure in the lines.
Connect the rod end hose and not the cylinder should be very close to full of oil.

Now you have to use the tractor hydraulics to very carefully line up the pins.

 

[Dedaisy]

Thanks... It is one of the two main lifting cylinders on the 7074 Montana. Bad weld on the end bushing broke. It has a ~ two inch shaft and the guy who had this tractor before did not grease it very often.. Got to replace the pin also. I had already replaced most of the pins on the loader...

 

[stormpetrel]

Just cycle the cylinders through several times. The air will be forced out.

Will it be the same for me with 8' of hoses, a new cylinder, and valve?

 

[Chilly807]

I've had one of the loader cylinders off and repaired, all I did was cycle the cylinder to the end of it's travel, then let the pressure go over the relief valve for about 15 seconds. After a couple times doing this each way there was no air remaining in the cylinder. Just where the air gets to baffles me though, it would have to go past the seals and into the reservoir...

Sean

 

[jonyyuma]

I had a few bad pins in mine when i bought it. You can buy the nice ones at TSC, with an oval handle.I could not find pins with zerts, so I bought cold-roll 1018 steel and drilled my own grease passages into them. just a thought. Jy.