Also needing help with a 973 cat G86 serial. The lift and bucket hydraulics are making chattering noises along with jerking operation. Hydro fluid level is good. Over the phone a friend said it was possibly the pump. However noise appears to be coming from something further forward of the pump up by the Hydro reservoir. Any Ideas appreciated.
from the way u describe it, sounds like pressure relief valve dumping pressure, how many hours on machine. have u had any hoses replaced lately. i would remove filters and cut appart to inspect for contamination,then jack up cab and remove pressure relief and inspect.the control valve is mounted above fuel tank.
The main hydraulic cooling hose going to the radiator blew and was replaced. operatated the machine for about 2 hours since then. Machine has 6825 hours on it. Just replaced all filters about 50 hours ago.
I have replaced the main mast pump and pilot pump about 50 hours ago due to blown seal allowing hydraulic fluid into the crankcase. Since then there has been intermittent jitters in the utility hydraulics but very sporadic. Once or twice in an 8 hour period. Now it does it continually with noticeable lost in hydraulic power. Drive hydrostat working fine.
sounds like pressure relief valve, pull hyd filters out and look at them, ( ones in tank ). you will probly find pieses of something in there. usually u will find parts of rag or dirt, when u change hyd pump lots of oil comes out suchtion hose so everone stuffs lots of rags into it and then u forget to take them all out, pieces will clog pressure relief pilot holes. most likely find evidence in filters. been here, done this myself sad but true. sometimes u can flush relief by opening it a couple times.
main hyd pump should not put hyd into crankcase unless hole plugged in pump housing, it to let hyd oil leak out of pump. i have seen peaple try to plug thinking they have a leak.
Thank you for the info, do you know anyone that would have a diagram of the hydraulic hoses showing exactly where the pressure relief valve is and how to check it out. I am not experienced with hydraulic systems. I will check the filters and reservoir first.
i'll try to print u out from the manual, its above fuel tank in main control valve, you have to jack cab up to get in there.