Hi friends, You've helped me on several occasions with this back hoe. I again come with a dilemma; the 2 inch by 18 inch low pressure hose connecting the hydraulic tank suddenly seems under pressure. It purges the hydraulic fluid from the flanged fitting to the pick up pump. I had gotten a new hose and upgraded threaded clamps. I could not get it to stop leaking while it runs and it purges when I try to load it by just moving the cylinders. I wonder if it has some problem in the pump causing pressure to 'bleed' into the low pressure side. The hydraulic tank is vented.
Hey Bruce, Are you saying that item #2 is leaking at the hose clamps (#1), but only when you are using a function? Did you use suction hose to replace item #2? There is a slight amount of pressure in the tank. The vent in the cap will maintain that slight pressure.
Suppose to be some pressure at the tank, keeps the pump from cavitating. Try running it without the cap for a minute. Reminds me of a funny, not so funny moment when a kid at the shop tried to change a hyd filter on a Kubota excavator without relieving the pressure first. Bright side was he'd never do that again, downside was it took him half the day to clean up the mess.
Are you saying it leaks at the hose connection or the #4 flange in Swetz's illustration? If leaking at the flange it's probably just the #5 o-ring. Next time you have the tank empty make sure and pull the outer cover to remove the suction screen for inspection. I and others have found a rubber disc come loose inside the screen that can possibly cause a blockage on the suction tube. Here are rough measurements to make a wrench to remove the screen with.
Side note here, what is the common way to relieve pressure from a backhoe hydraulic system? I can't find a simple explanation in my manual.
Shut the engine off. Operate all the hydraulic controls. There may be some pressure in the tank that will release when you loosen the cap.
Yes sir, that is where it leaks from when the machine is running. And where it sprays from when trying to use cylinders
Is there any chance possible that there is a hose above the suction hose that is on the pressure side, that is leaking down on the suction hose. What you describe sounds exactly a blown function hose, in that it only leaks slightly when just running, but then leaks profusely when under pressure. The suction side should never see pressure like this, and if it were leaking it would most probably be when the machine is off as there is usually a very slight vacuum at the inlet of the pump. Sometimes a leak when the machine is off, goes away, or even causes cavitation in the pump when it is running.
I look at the pump. It has no new wet hydraulic fluid on anything above the hose
I was more thinking a hose than the pump. I have seen some leaks that sprayed a fine spray across, and you really couldn't see the leak. My thought is that may be happening. If possible, get an assistant to hit a control handle as you look under the tractor. Sometimes this is the only way to find it. Other than that, I am plumb out of ideas...
Suction hoses that slide over pipes will not spray oil out of the connections. They will drip or ooze, but not spray. Unless it is wrong ID size hose and or wrong style clamps that will not tighten properly. Another possibility, but not likely cause would be not enough hose overlapping the pipe. Lastly --- a damaged hose.
Ok fellows, once again I eat words (and plenty of hydraulic fluid). My friend came over to help, new pair of eyes, ok fine. I tell him you guys view; that it's the high pressure hose that may behave as mentioned. We looked at the high pressure connection, wasn't really tight. When we opened it, the o-ring was destroyed. You folks had diagnosed it once again. Back at the hydraulic tank, one of the threads describes the making of a wrench to remove the filter. That and a cheater pipe and done and done. Filter was a bit rusted and the last of the tanks hydraulic fluid was not chock full of debris as we wiped it dry prior to re-installing the 'cleaned up' filter. We replaced about 5 gallons of the lost fluid. I'll get another 3 five gallon jugs to have some spare. I think it was the high pressure line as you had tried to insist. So this, as usual, is by way of apology for being hard of listening. Thankfully you are kind, and repetitive. I will test with more fluid and report in a few days. Thanks.
You are right. And I am slow at listening. I apologize. When we pulled the tank 2 inch low pressure hose and put a wrench on the high pressure hose connection, which we could now get to, it was not tight. When we opened it, the o-ring was broken. You had diagnosed it correctly. We changed o-ring and snugged that big nut down. No leak! I only had about five gallons of fluid to replace the empty tank. Don't think I've fully drowned the filter in fluid. The hydraulics had purged quite a bit over time. So, it's very, very slow in articulating the hydraulics. I'll get a few jugs tomorrow, see if it starts to clear air from lines and breathe backhoe fire, once again. Will report in a few days. Thank you, Mr.Swetz
Glad to hear you sorted it all out!! Best part is it was an inexpensive fix...besides the oil, that is . Happy tractoring!
Got two five gallon jugs of hydraulic fluid. $ 200. Put them in the machine, and now the monster of the Midway is BACK!!! It works great, no leaks. Machine is hoisted up on outriggers and the the front loader plowed down. Boom at full extension. Set it like that about 6 hours ago. Has not lost any height or extension. It might be better than ever.
I got two jugs of hydraulic fluid (all they had at the store)The machine is leak free and has max power. No cavitating! Everything articulates magnificently. Thank you, dear man!