Hydaulic oil pressure

[agroman]

Before taking the top off hydraulic chest I checked oil pressure with a gauge attached to trailer tip fitting. Pressure relief valve blew at 600psi. I see from info it should be 2500 ish. This reading was taken at 1600rpm with hot oil as per instructions. Interestingly at idle 650rpm the valve keeps pressure at 2000psi if deadheading it.

Does anyone have ideas of diagnosis of low pressure? Will shims in pressure relief valve correct this? or is there something else wrong that I need to look for?

[Brian]

Are you saying that the pressure reading is 2000 psi at 650 rpm yet drops to 600 psi when reved to 1600? If so that sounds like a blocked intake filter.

Did you take the control lever beyond the top stop on the quadrant to ensure the "knock off pin" is not in play and has moved the control valve into neutral?

[agroman]

Yes pressure is higher at idle. could be just blocked filter, I will find out when I get the top off, someone had taken the top off in recent history as it looks as if they have used some instant gasket to reseal rather than a new paper gasket. To get a pressure reading I raised quadrant lever to the top of normal travel. I am not sure of the linkage set up / ware as someone has unbolted the two halves of the quadrant so that the lever will move to a higher position that it should to achieve full lift.

At idle and under load the pump makes a clattering sound, which stops if you increase revs.

[Brian]

The filter is to the left of the drive tube and you will need the pump out to get it out. Pump should not be making a noise other than the relief valve blowing, could be a drive key sheared and the gear is spinning on the drive shaft at higher revs.

[agroman]

Thanks again Brian for info!

The learning curve is starting!
I will pull the pump out and check out the drive. The pump is working consistently, no problem with loader work other than 'break-out' ability when the bucket is driven hard into a pile of poo! its ok but will blow relief valve if it is particularly heavy.

Anyway got the loader off this evening and gave her a good degreasing and pressure washing. Now ready to get her in the workshop and pull her to off! One bit of good news got the rev counter working for the first time in about 25 years thanks to a new cable from Agriline.

Whilst she is of the road I am planning to take off the fuel pump and injectors and send them off to Peter Strong for a bit of TLC! Have also go new fuel primer and pipe work to fit.

Just need some excuses ready for Mrs. S as to why I am constantly hiding in my workshop!