Blew up hydraulic pump on Yanmar 4220 D.

[Gary Fowler]

The hydraulic pump casing cracked due to pressure too high. Tech at Hoye tractor said it was because a blockage somewhere. Anyone know what would cause a blockage and where it might be. The tractor is a Vietnam rebuild with FEL and therefore is not a detachable FEL so no couplings to be loose. Is there something in the FEL joystick valve that could get blocked. It was working perfectly till it blew oring which was replaced then seal started leaking so bolts were tightened a bit and then the case cracked. Brother in law welded the case up and put it back on and it worked the 3 ph but when he hit the FEL joystick to raise the bucket the pump exploded again. It must be something in the FEL control valve but I dont know much about how they work other than which way to move the joystick to make it work. Any one with advice on this or that has had this problem and fixed it please chime in. The pump is $549 so dont want to blow another one.

 

[wdchyd]

Best thing to do in your situation....

-install new pump

-add a tee between the pump and the next component

-install a "direct-acting" relief valve preset just above the tractors max pressure ( Prince Adjustable Relief Valve — 1/2in., Model# RD-1850-H | Relief Valves| Northern Tool + Equipment )......the valve pictured can be used as a tee cuz it has 2 pressure ports and 1 return to tank port.........you will need a hyd guage to set and another hyd source to help adjust is helpfull

-the valve can either be inline with a hose hanging off or the tee inline with the valve hanging off a short hose

-put the hanging hose (or valve) in a five gallon bucket

This will allow you to troubleshoot tractor and giving you a visual if the hyd pressure spikes above recommended settings without replacing another pump if you cannot find the problem right off

ie: main tractor relief valve setting at 2200psi.........set the extra relief valve 2400psi

I have done this many times in problem cases, it beats replacing the pump prematurely.......the only oil ending up in the bucket would have been too much for the new pump.......I use a flow/test meter after a new install from catastrophic failure

Sorry, this setup will not cure your pressure spike but will save the new pump from doom.....

I never seen a rewelded gear pump housing hold up.....:confused2:

Hope this helps......:2cents:

Bill

 

[wdchyd]

BTW, your pump may have been coming apart internally or maybe there is no suction screen in the reservoir tank and something got trapped in the FEL relief valve.....I'd open it up to inspect

 

[winston1]

If the 3 point worked with no problem after your temporary pump repair and it whamoed when using the loader it sounds to me like it can't be anything but the joystick. I would follow the experts (wdchyd) advice and open it up. Got to be something amiss in there.

 

[deepNdirt]

Been there done that, cracked the pump wide open on my YM,:ashamed: but was a mistake when I allowed a friend to reverse the lines connection to the control valve in attempt to find out why it was only lifting and not going down,
it turned out I should not have plugged off the dump line,

As mentioned having no relief valve in the circuit is why it happened, check the PB adapter and the inlet port of the valve for a blockage, though you did state the 3-pt was working .. meaning the circuit of fluid must be cycling through and reaching the 3-pt, the dump line should not have any high amount of pressure from it, although I would imagine if this line were to be clogged it could cause some pressure buildup in the valve as I stated with my previous experience, I wouldn't chance using it again without first installing a relief valve,

 

[Gary Fowler]

What about the tractors relief valve? Where is it located?

 

[wdchyd]

Most are in the FEL control valve next to the inlet from the pump

 

[winston1]

What about the tractors relief valve? Where is it located?

The tractor relief valve is located in the 3 point control head. Your over pressuring is happening before it gets to that point therefore that relief valve is not going to help you. There should be a relief valve in the joystick control valve. My Bulldog loader has one in it. Still going to have to get into that control valve.

 

[deepNdirt]

Is the 4220 equipped with an accessory block? or was the lines cut in order to tap into the hydraulics?
I'm not that familiar with the larger tractors,

 

[Gary Fowler]

I just talked to my BIL and he has the control valve off and a mechanic is going thru it to either rebuilt it or turn it into a trotline weight and put on a new one. Hopefully that will correct the problem. I cant see it being anything else as it was all working fine then the seals started leaking and when the leaks were fixed and everything tightened up then the case cracked. I dont know why the relief valve would suddenly stop up or quit working though. Maybe it would be a good idea to have an inline one on a tee permanently installed for safety.