X728 hydraulic problem

[mikefamig]

I just removed the mowing deck on my X728 tractor to install the snowblower and there is no hydraulic power to the front hydraulics. I switched the stop valve over to supply fluid to the front implement and attached the front quick hitch and the hydraulics are dead. It does not lift and it does not angle.

The mid lift mower deck lifts just fine. The wheels drive with power and the power steering also works well. I also attached my Johnny bucket to the hydraulic attachments on the tractor with the same result, no movement in the bucket when I move the control levers.

Being that the mid deck lift works I assume that the scv spool is working to raise and lift it. The fluid is full and if the filter was blocked then there would be other problems. I'm thinking that there is some problem in the selective control valve. Has anyone had this problem?

Any help would be appreciated.

TIA, Mike.

 

[beenthere]

The valve needs to be closed... to switch supply from the deck lift to the snowblower

 

[mikefamig]

The valve needs to be closed... to switch supply from the deck lift to the snowblower

Thanks for the reply but that's not the problem. the valve is closed to divert pressure to the front attachments. I have forgotten to close the valve in the past and the front attachments still worked but with less power and unevenly. This is different. When I move a control lever the engine strains for a moment and then runs freely and the front tool does not move.

Mike.

 

[beenthere]

Re-connect the quick-connects to see if one is not seated properly..

 

[mikefamig]

Re-connect the quick-connects to see if one is not seated properly..

I did that and I also disconnected the hitch, connected my Johnny bucket and got the same result.

 

[mikefamig]

I suspect that there is a pressure relief valve inside of the scv that has failed but I am not familiar with the unit. The scv works to raise and lower the mowing deck so that lever/spool is working. If one of the spools failed I would loose either the lift or the angle but not both (I think?). The scv is a black box to me.

The dealer service tech told me that there is a pressure relief valve under the seat but if that had failed the wheels would not work. I have read that the system delivers fluid from the reservoir to the steering valve and then to the scv and then back to the reservoir via filter and cooler. the steering is working fine so I strongly suspect trouble with the scv.

Mike

 

[beenthere]

Correct hose connections? Not crossed?
Suspect something simple.. The SCV is pretty simple.. two spools, one with the detent to put in float position.

If the deck spool worked, then one of the two functions to the snowblower should also work. But if angle or lift do not, leads to crossed line connections.

Maybe not.. just a thought.

 

[mikefamig]

Correct hose connections? Not crossed?
Suspect something simple.. The SCV is pretty simple.. two spools, one with the detent to put in float position.

If the deck spool worked, then one of the two functions to the snowblower should also work. But if angle or lift do not, leads to crossed line connections.

Maybe not.. just a thought.

I hear ya that it does appear simple and I have done dumber things in my life but I have looked at it over and over again and it's hooked up correctly.

The fact that I lost both lift and angle eliminates many things. A bad coupler would fail only one function. The same is true of a bad spool.

Swapping the hoses would make the lift work backwards. I still have the color coded caps so it's hard to hook up the hoses wrong.

All of the evidence suggests that the scv is just passing all fluid back to the reservoir. When I push the control lever the engine strains for a moment and the hitch twitches and then the engine goes to running freely. It is as if a pressure relief of some sort is breaking open at low pressure.

I have been doing this hook up for seven years now. I use the bucket in the spring, the mowing deck with bagger in the fall for leaf collection and the snow blower in the winter so Im very familiar with the hookup.

 

[mikefamig]

Correct hose connections? Not crossed?
Suspect something simple.. The SCV is pretty simple.. two spools, one with the detent to put in float position.

If the deck spool worked, then one of the two functions to the snowblower should also work.
.

Agreed unless the pressure was being lost after the mowing deck lift and before the scv spools.

Mike.

 

[mikefamig]

Beenthere

Thank you very much for your help and you called it right. I had the hoses hooked up to the right color connector but they were the wrong two hoses.

I only use the lift on the quick hitch when using the snowblower. I connected the green and gray hoses when I should have connected the green and black. I was connecting the hoses in pairs instead of all four at the same time and I was using the wrong pairs.

DOH! It sucks getting old.