656 hydraulic issues

[AJTEETER]

I put a new hydraulic pump in my farmalll 656 and now it makes a loud buzzing sound whenever I change the lever for the fast hitch or whenever the weight changes on the hitch it will stop when I charge the position but I have to constantly change it or the loud buzzing comes back it did it a little with the bad pump but really bad now

 

[Janicholson]

Pilot valve in the Safety/regulator valve block has a screen, and a drilled hole in it. If the screen is plugged, or the hole too small from a check ball beating it closed, it will do that. Jim

 

[pete 23]

Did you replace the suction tube with seal from pump to recess in the housing or did you measure to make sure the new pump would seat that tube seal same as old one. Sounds like you are sucking air and possibly through that seal. Filter of course has to be clean to prevent cavitation. There is a hose that you can view from the rear 3rd arm cover to make sure it is not off, kinked or leaking that will also suck air.

A 656 does not have that valve with orfice that plugs. Different system. Other possibilities also of course.

 

[Janicholson]

Just trying. Jim

 

[pete 23]

I know, can't be familiar with all models.

 

[AJTEETER]

I did have a issue with the tube when I installed the pump I don?t think it was all the way in the pump and there was a lot of cavitation so took it back apart and solved that and cavitation went away now it?s more of a buzzing sound in the fast hitch and also when using the remotes if you open them just a little also there is a block below the seat with two lines going into and three bolts I think is that the relief valve or the block Jim was talking about thanks

 

[pete 23]

That block with the two lines is just a junction to connect flow for hitch with one line and lube to parts in transmission with other line. It does have a plastic check valve under the plug and it would be easy to pull that and see if check valve is damaged which I seriously doubt.

I would be interested to know if you have excessive back pressure in hitch flow. I would install a gauge in the plug near pump that feeds hitch. Should be very little pressure, like less than l00 psi with hitch in neutral, not lifting anything.

There are ways to test for this without a gauge but difficult to explain on here. I take it that the buzzing stops while you are raising the hitch. This would indicate your hitch circuit is staying on pressure due to unloading valve not dumping due to a leak behind unloading valve. Of course all those parts are inside under the seat, under that flat cover.

 

[AJTEETER]

Pete thanks for your help I think you are correct about staying on pressure the buzzing stops when I raise the hitch unfortunately I don?t have a gauge to measure pressure but it acts like the whole system is under pressure I drove it some yesterday and the buzzing happens also when you turn the steering a little or you open the remotes a little bit but stops when you open them all the way or turn the steering quickly also all the pesky drips in the system have gotten much worse as well as it blowing a couple of low pressure lines when I first changed the pump I believe I had the problem before I changed the pump but with the bad pump it was much less severe is there a main relief valve that may not be opening or should I be looking at the unloading valve under the seat thanks

 

[pete 23]

Try putting position control lever fully down into the action control offset (slow fast) spot. If that relieves the strain your problem is in just the hitch section . Hith has own pump which I am sure you know. When hitch is not being raised the flow

from hitch pump joins with flow from main pump at aux valves. If the unloading valve is not opening to allow hitch pump flow to join main pump , the relief valve for hitch (which is seperate from main pump relief valve ) has to open. By putting lever fully forward you dump hitch pump flow .

Would be best to have a gauge so you can determine if both pumps are under pressure or just hitch pump. I doubt that they both are.

 

[AJTEETER]

I think I may have been over thinking the problem. I ran the tractor yesterday and the noises were worse including cavitition so I think the problems may still be in the suction line to the pump. All the hydraulics make noise including the power steering which I believe is a separate system at least it has it's own pump so it makes sense that both pumps are introducing air into the system. I will pull the pump and replace the seal on the tube and o ring in the pump and see if that cures the problem. Thanks