Bobcat 743B Hydraulics

[Marc Martello]

My name is Marc and from country NSW in Australia, thanks for allowing me to join. Diesel mechanic by trade and enjoy anything mechanical.
I have an old Bobcat 743B and today developed a very unusual problem with the hydraulics, for some reason all the lift arm and bucket hydraulics do some crazy stuff, like 4 in 1 hydraulics do opposite to what the control is meant to do also on lift arms go opposite way for a small amount only, after working the levers for a short time it comes good again, never seen this before, has this happened to anyone else machine ?

 

[Chris 8603]

We had a jd machine do something similar to that. Turns out the valve body was leaking by on the spools and the pressure relief valve was weak. It would drop as soon as you tried to raise the arms and then go up. If you had anything in the bucket, then it would drop and try to raise but couldn't because of the valve. It did all this just all of a sudden.