751 Bobcat malfunction

[WVRoger]

Today I had my backhoe attachment on my 751 skid steer and it worked exceptionally well but I needed to remove it and use my bucket to move some dirt and rocks. Well after detaching the backhoe hoses I could not lower the boom or tilt the attachment point downward! I suspicion one of the attachment point check values are sticking or failed! Has anyone experienced this and if so how do I fix it?
On another note I hooked the hoses back up, started the machine and the boom smoothly lifted and lowered and tilted as designed!

 

[spitzair]

Sounds like your auxiliary hydraulics got stuck on. Try reversing the auxiliary hydraulic flow momentarily to hopefully unstick the valve and then disconnect your hoses and see if the problem is still there. If it is, start by checking to make sure there’s no power going to the auxiliary solenoids on your control valve. If there isn’t any, try giving it a GENTLE tap on the end of the stem to knock the valve loose. If there is power to one of the solenoids you’ll have to figure out why… I’m not familiar with the 751 but if it’s anything like the 873 I have you have a PWM (pulse width modulator) that allows you to feather the auxiliaries but I have no idea how exactly it works or where it’s located in the machine. For continuous flow such as when running the backhoe I think it just gets full system voltage to one of the coils but I could be wrong. Hope this helps at least a little…

 

[WVRoger]

Thanks, it gives me a place to start. It concerns me that it works when something is connected to the check valve adapters and does not when nothing is hooked. You are right something is sending fluid in the wrong direction and not controlling the boom or tilt function!

 

[reaperman]

Oops.