Hydraulic Questions - Cylinder rebuild on a 2006 553

[gable74]

Cylinder seal kit #7135536. Anyone know what size nut is in this kit? I want to be sure I have the right impact socket before tearing down my cylinder.

When bucket is curled all the way up, it will drop completely down in roughly 30 - 40 seconds without any weight. Hoping its just the cylinder seals. Also, would a leaking cylinder affect the auxiliary hydraulics? Seems like I am not getting full flow on attachments.

 

[gable74]

Will be re-sealing the tilt cylinder this weekend, so will let you know if this repair has any effect on the auxiliary hydraulics.

 

[gable74]

The nut was 1-1/2".

Found the issue with it drifting down. The piston was scored pretty badly and the inside of the cylinder was scored some as well. I re-sealed everything since I had it open. It stopped the drifting down issue for now. I can only assume given the damage, its not going to last long. Pretty sure I have a cylinder replacement in my near future. what causes that to happen? I will post some pics a little later.

 

[brdgbldr]

The nut was 1-1/2".

Found the issue with it drifting down. The piston was scored pretty badly and the inside of the cylinder was scored some as well. I re-sealed everything since I had it open. It stopped the drifting down issue for now. I can only assume given the damage, its not going to last long. Pretty sure I have a cylinder replacement in my near future. what causes that to happen? I will post some pics a little later.

Any debris that makes it into the cylinder can cause scoring. Also, if the seal is severely worn out the piston can rub on the cylinder walls.

A lot of time people will replace the seals and not be careful about keeping everything clean. It only takes a grain of sand to destroy hydraulic systems. If you go into a good hydraulic shop it will be spotless. If it isn't, find another shop.

 

[gable74]

It looked like someone took 80 grit to this piston. It's been scraping badly for a while. You could hear it grinding as I pulled it out of the cylinder.

 

[Tazza]

WOW, that sure is some nasty scratches on that piston, i don't know what particles you got in there to do that damage, but i hope the filter caught them all.

 

[gable74]

It's a new machine to me. I will have to thank the previous owner.

 

[gable74]

Got the new tilt cylinder installed, all went well. Unfortunately, it did not make a difference with the auxiliary flow. Brush cutter boggs down fast and barely stays spinning under load. It's a low flow brush cutter, 10gpm - 16gpm.

 

[foton]

I know you do not want to hear this but the bobcat dealer has the equipment to test the pumps pressure and flow rate. after seeing that piston I think it is your next step. It would be interesting to check all the filters in the hyrdo system to see how much they caught.

 

[gable74]

Yeah, I was hoping to not have to do that. They let them sit outside until they work on them and I don't have an enclosed cab. I replaced the hydro filter and as much fluid as I could. I was hoping the brush cutter had a governor/safety on it or something since it was new. My grapple works fine buts its obviously not as demanding for pressure/flow as the brush cutter.

 

[Stumper1624]

Seeing the condition of that piston I would lift the cab and check all the inline filters. especially the one just under the tank.

 

[gable74]

I didn't see any other filters other than the large screw on filter in the engine compartment. There are more inline filters? I don't remember seeing them in the service manual either. 2006 Bobcat 553.

 

[Dave1234]

Got the new tilt cylinder installed, all went well. Unfortunately, it did not make a difference with the auxiliary flow. Brush cutter boggs down fast and barely stays spinning under load. It's a low flow brush cutter, 10gpm - 16gpm.

Can you tell me the brand of your brush cutter, and if you had been happy with its performance prior to this problem? Can you describe what it would readily cut? Thank you very much.I have a 11 gpm 742B and am wanting a brush cutter, but the ones I see take higher flow.

 

[Dave1234]

It looked like someone took 80 grit to this piston. It's been scraping badly for a while. You could hear it grinding as I pulled it out of the cylinder.View attachment 5977

Your description "scraping badly when being pulled out of the cylinder" suggests to me grit entering from through a failed wiper seal on the rod, more than from within the hyd system, but the scratches on the piston say a lot of grit got past the piston and thence secondarily throughout the hyd system from both sides. I wouldn't be surprised if the previous owner also rebuilt the cylinder to sell it, after ignoring needed maintenance for a long time. It got it out the door, but not very far after that.

 

[gable74]

It's a blue diamond heavy duty brush cutter. Rated for 10 - 16gpm flow. It was brand new and never operated correctly with my machine. I hoped it was due to the lift cylinder issue, but after I replaced it, it didn't change the performance of the brush cutter. I have an 863 at work I plan to hook it to soon and see how it works paired to that.

I also suspect the machine was sold to me knowing there was an issue. The only other thing that would cause this issue would be the control valve or components within, I would assume. They are like $2k new.

 

[gable74]

Well, I threw in the towel on trying to figure out the aux issue. I assume its the main hydraulic module which I dont want to spend the money to replace. I bought an s150 and plan to maybe just keep the 553 as a backup for the small jobs. The s150 runs the brush cutter really well. It has 1300hrs on it and is a considerable upgrade in performance. Thanks for everyone's help!