New to me Hitachi EX270LC (i think the previous owner said 1989 model) and it is leaking hydraulic fluid at the dipstick on the back left engine bay area. History on this thing, i know the previous owner for many years, been using it from time to time before buying it and it's been doing this since they owned it. Not sure it was ever looked at as the owner just kept putting hydraulic fluid in it when it would go below the low line. It's not leaking bad, but a 2 gallon jog keeps it full till about a month of use. The previous owner thought maybe it needed to vent, so they kept the hydraulic fill plate kinda loose, but nothing changed. Ant thoughts what that could be? Thanks.
IIRC the dipstick is for the gearbox oil level and hydraulic oil doesn't belong in there at all. If fluid is coming out then one of the shaft seals on a pump is leaking .
You’re talking about the fill plate on the hydraulic tank ? When working the machine the hydraulic tank becomes slightly pressurized to help force the oil to the hydraulic pumps.
Ok, i'll make sure those are tight from now on.
The only issue i have with this is the main 4 inch tube coming from the hydraulic tank goes straight into the side of the engine where this dipstick is, and i would think after all these years of the other owner just adding hydraulic fluid to the tank (if that's something different) wouldn't it have ran out of fluid by now? plus, there's no other leaks anywhere else? so i don't know where the hydraulic fluids going?
Got a picture of where its leaking from?
The dipstick is for the gearbox oil level and the only reason for oil to come out there is because the gearbox is over full. There's 2 places were that can come from is the engine(rear main seal failure)or hydraulic pumps (input shaft seal failure). An oil sample will determine what the extra oil is That gearbox should have nothing but gearbox oil in it as per maintenance manual
I hate to disagree with you, but a rear main seal wont leak into and overfill the pump drive gearbox. It'll either be the input shaft seal on the pilot pump or input shaft seal on one of your two implement pumps. Id start with the pilot pump since its quick and easy to replace or reseal.
It's OK to disagree, if the bellhousing is full of oil were does the engine oil migrate to next? I'm only considering possibilities not probabilities and that's why I reckon a oil sample is a very easy way to find out.
Out the bottom of the flywheel housing. Theres a seal on the input of the pump drive that the engine oil would need to make it past as well for it to overfill from the rear main. i would suspect there would be a mess underneath the flywheel housing if the rear main was filling it with oil to the point it was pushing past the input seal on the pump drive. I guess you could be correct, but its pretty unlikely, and for what its worth(not much, this is the internet after all) not something ive ever seen or even heard of happening. Ive resealed lots of pilot pumps for leaking into the pump drive gearbox though, and done my fair share of rear main seals on excavators.
Unless someones sealed the pump drive to the flywheel housing, which would be pretty sweet!