What is this and why is it leaking?

[bdoyle]

I tapped into my tractors hydraulics to see if my backhoe works. Well all cylinders worked but I had a leak on the control valves. It looks like a large screwhead captured in a thinwall tube and is on the lower left of the valve block. Fluid seeps into the screw head slot. So what is this guy called? Should be able to drop a deep socket over it tomorrow but looking for a little info first. This is a used LW-6 backhoe that I just picked up. It was made in 2004.
Thanks,
Brian

 

[Leejohn]

Looks like to me to be the relief valve adjustment screw.

 

[bdoyle]

I was wondering that also. The screw head seems to be split and does not want to turn. Just using a regular screwdriver though. More investigation necessary... There looks to be a dent in the outer tube, staking? Guess I'll take it out this afternoon.
Just had another thought. Could it be a flow control valve? There are two on the vavle body assembly.

 

[Gary Fowler]

I agree that it is a pressure relief setting. Remove it and likely there will be an O-ring gasket that is screwed up.

 

[bdoyle]

Here is the culprit. Took it apart and the orings seem a bit small. See if I can fit some new ones tomorrow.