Hi, im new to the forums...I have a 1990 PC300 that had been left unused for about a year, it was working perfectly fine when it was last on... the engine started up fine the other day, but the hydraulic pump is making an erratic whining sort of scraping sound...its unable to move the arm or tracks, they only slightly jerk a little when trying to move my first thought was it had some how become low on fluid, so i added 10 gallons of 10 weight oil...the sound was mildly altered, and it still cant move what do you guys think it could be? needs more fluid? or do i maybe need to somehow bleed air out of the system? or something more serious?
What position are the arms in?(tucked right in, or fully extended etc) On the side of the hydraulic tank there should be a sight glass, is anything showing in that? It is possible that air needs to be bled from the system but answer the above questions first. Shane
yea do not run it long until you are sure it has plenty of hyd oil. if it was low enough yes the pumps could need blead. how low on hyd fluid is it
Is there a shut off valve going to the pump? I think its the -3s that have a ball valve around the pump area, and if its closed the tracks will work slightly but nothing else will. Check that and if not be sure it has oil.
If the ball valve is turned the hydraulics won't do anything. The valve sends the pilot pump oil back to the suction side of the pump. Since pilot oil runs the main pump as well as the pilot controls nothing will work. We used to see the issue all the time on logging machines. The chaser would throw a rain coat under the pump and the warm air off the engine would dry it out. He would pull the rain coat and catch the valve shutting down the machine. People would scratch their heads for awhile until someone called the dealer or just remembered about the valve. As for this problem it would be hard to say. The machine is real old for a Komatsu. All those little spools in the pump controls get full of crap and then stick in place if the machine has been sitting for some time. I've also seen people dump crap in the hydraulic tank plugging up the suction strainer. That could be the noise. If you pull the cover that the fill cap is on you will see what looks like a pipe with a spring in the center. Hopefully there is a spring anyway. Take the spring out and set it aside. Pull up on the pipe and the suction strainer will be on the other end. If you see any brass you got some problems. If you see a lot of brass, get one of those great big beach towels to cry in. If the pump is shot you just as well cut the machine up. The last Dash 3 or 5 pump I rebuilt ran $7,500 and I charged a whole lot less than the dealer does. I doubt there is an exchange from Komatsu anymore. Good Luck!
the arm was extended outward with the bucket curled, i left it like that so try and keep the visibility of the machine from the street to a minimum, to avoid thieves and vandalists i dont recall seeing the sight glass anywhere, im going to search around for that today if the system needs to be bled, how do i go about doing it? not sure if theres a valve, ill check today....if there was i dont understand how it would be in the off position as im the only one with the key that ever works on the machine
i pulled out the screen in the tank today...it wasnt brass that i found stuck in it, but rather thin film of gunk wrapped around it...after cleaning it off, i stuck it back in and started it up...the hydraulics work perfectly now...im amazed what a big different wiping it clean did thanks for the help everyone
If your oil is so bad that all you did is clean the strainer, you better think of draining that tank and change some filters. Glad your back running.
definitely something id like to do...i just need to find a local place i can get 50 gallon drums of 10 weight oil...using 5 gallon pales is expensive and troublesome as the stores mostly only stock like 2 of them a week
The extra cost of that oil is nothing compared to the cost of that pump. I would recommend not running it till you got is changed. Good Luck!