Hydraulics whining

[76450c]

76 450c with 6 way blade, just had control valve completely rebuilt, problem im having is when cylinder is either fully all the way in or all the way out the valve block starts screaming until let off. Seems like relief valve should be dumping at that point. Any ideas?

[Jim B]

Do the pressure checks and see what the relief is set to. To high could damage or destroy the pump.

[76450c]

So the boss 90 where the test port coming off the pressure side is no longer on the new boss, looking in manual but don’t see another place you can test it.

[Jim B]

I can't see it. Any ideas from the person that rebuilt it and used a part without the port? If I couldn't find another port, I would look at getting a Tee into a cylinder connection using true hydraulic fittings, not hardware store pipe.

[76450c]

So it’s deadheading at 1750 psi, but just kills if you continue holding it

[Jim B]

Pressure is supposed to be about 2250 psi isn't it?

When you say deadheading is that when the cylinder stops traveling or does the gauge keep climbing if you hold it in?

Do you know if the relief valve was disassembled during the rebuild?

Did you rebuild it or did a shop? I it is a shop you should be talking with them.

[76450c]

Jim, it was two lines swapped, I had dozer down to transmission and going back together I guess I swapped them. Dozer is 1750 psi

[Jim B]

Crossed lines would do it, Glad you found it. Good luck with your machine.

[Stan Disbrow]

Hi,

Yep. That's a potential problem with hydraulic lines. They don't immediately tell you when you cross them up. Unlike electricity. That tells you Right Now!

Stan