Bought this komatsu pc150-3 and it runs good. BUT....now it has started leaking hydraulic fluid at the overflow just below the pressure fill cap. When you take the cap off it doesn't have pressure behind it like it once did and the machine starts to lose power if used for an hour or so. My simple small brain tells me it is the cap gone bad and letting the pressure force fluid out the overfill tube....making it lose fluid and eventually power from fluid loss. However some posts I have seen on here say things like...pump going bad/ main seal problem/engine problem/bad filter (changed the filter already though) can cause this type of leak and power loss. My shop book with this machine is kind of vague on this problem....figured I'd go straight to the pros and ask. So what do you think?
I think you need to post a photo of the cap you are talking about. There is no overflow on that hydraulic tank. By chance is the fuel tank and hydraulic tank next to each other?
Yes fuel and Hydraulic are side by side. Right beneath the pressure cap there is a line leading out (like on a radiator) half inch down from cap. Ill try to get a picture and post it. Thanks for the reply
Yes fuel and Hydraulic are side by side. Right beneath the pressure cap there is a line leading out (like on a radiator) half inch down from cap. Ill try to get a picture and post it. Thanks for the reply
Over look the grime. Happened right in the middle of clearing and burning some land. LOL. But that is the line that is leaking the fluid
I don't think the oil level should be that high. does it have a sight gauge on it .if it's not holding pressure you most likely need a new cap but it still shouldn't be that much oil in it most of the time the oil level is about a 1/4 of the way down in the tank so you have room for expansion and air pressure to force oil to hyd pump so it doesn't cavitate.
No it doesn't have a sight gauge...wish it did. I'll pump some of it out and try a new cap. I appreciate the help and will let you know how it turns out
does the pump sound like it's cavitating when it loses power.
don't really know what that would sound like. It does make a groan on heavy lifts when putting piles on the fire. It just gets sluggish and doesn't pull/dig as strong as I know it can. I would say it loses over half power
It should, unless someone removed it and plugged the holes. Also, all excavators need to be in a position noted by the manufacturer to fill to proper level in the tank.
I've seen the fuel tank / hydraulic tank combo crack in between them and transfer fluid both ways. By chance do the two tanks come to the same level after running for a bit? You check the hydraulic oil level with the stick extended, bucket all the way open and the boom down so everything sits on the ground. Over filling will also cause the problems you are talking about.
Nope... no sight gauge. But the tank is different than the one in your diagram so mine could be an older model or something. The fuel level is good and doesn't show any transfer of fluids to either tank. Had My father watch while in use and all the fluid came from the hose I described. Im going to pick up another pressure cap and pump out some fluid and give that a try tomorrow. I really appreciate the help and advice. As a new guy on this site.... I think its great to see people help each other out on here. Ill give and update. Thanks again
Then I have no idea what machine you have. That's a pic from the PC150-3, I also checked the -1, it has a different fill cap, and the -5 which is a more square tank, and all those models show a sight glass on the tank. Furthermore, and I wager pretty much everyone here will agree with me, I've never seen an excavator hydraulic tank that doesn't have either a sight glass or a dipstick to check the level, and by far most excavators used a sight glass because they use a pressurized system which would blow out a dipstick. If it didn't have a sight glass from the factory that would be a first for me.
where/who did you get the machine from was it a local there wasn't a lot of the 150-3's around here that i can remember mostly was the 200's
Maybe there is some sort of baffle in the tank broken loose that's allowing a great amount of turbulence in the return flow? Causing the oil to fly all over and get foamed up? Really no reason oil should push out through that cap unless tank is way overfilled?
Sorry for the delay in replying. Turns out the cap was fine and it was overfilled with fluid. The tank cover had been reworked due to damage and when you dug in to it there was a fill marker tube and not viewable. Its so dirty it cant be read though. It still gets slower and weaker after about 3 hours use but that could be from getting too hot maybe? The temp on the inside gauge reads above normal when it does this but if I shut the machine down for a while and it cools down it works like normal again. I got this machine from a farmer in the area that had it for 11 years or so. A lot of the cab and surrounding metal and covers has damage ...even the door and roof, but it works pretty good and shows only a little over 3000 hours. Had to have the main boom cylinders and the top cylinder rebuilt, replaced the fluids/filter on hydraulics also. Should have changed the screen to guess i'll do that now since I have dug into uncovering the tank cover repairs. The leaks have stopped though thanks to the advice of you pros. Thanks again.