hydraulic pump adjust

[jbernd56]

I have a 40C and have very little downpressure on the blade. Is there any adjustment on the pump or bypass. Can the pump be rebuilt?

[Jim B]

Assuming you are talking about the cam driven pump mounted on the front of the engine. There is no adjustment on the pump. The control valve likely has a relief valve. Your service manual should give you information on how to check hydraulic pressure. Do you have a pressure gauge to check it with? I believe the pressure on a 40 was less than 1000 PSI, so a 2000 PSI gauge will be plenty. Adjusting the relief above the specification can destroy the pump. As far as rebuilding the pump, check with Lavoy. From what I gather parts are few and far between.

It is possible yours has a non JD blade, valve and cylinder(s) mounted on it. Do you know what brand and model blade you have? If it uses the JD tie rod cylinder(s) of that vintage it may need the piston cups in it replaced. It is possible for one side to be bad and not the other. Lavoy generally has the parts to repair those cylinders.

[Lavoy]

Most likely the seals in the cylinders are bad.
Lavoy

[Buckhorn]

If you disconnect the hose on the rod end, and apply down pressure, there shouldn't be any fluid coming out of the cylinder.
Do one side at a time. Some cylinders are easier to rebuild than others. On my 420 the blade would drop after a few minutes, and the seals
were hard to find, so I bought new ones.
If you need new ones, I can PM you a link to where I got mine. Cheap price, and fast shipping.