i was told the machine was self bleeding but i believe the machine has air in it.the boom was raised with the manual lower valve open.i do not have any controls aux or engine pump. also was wondering how much hydraulic fluid needs to be in the tank to prime the system.it was around the low mark and has been filled but i still have no controls.any help is much appreciated.thanks
If I recall, the 40F draws right out of the bottom of the tank about 4 to 6 inches above bottom. Suction line pretty much is level with pump inlet, it should be self bleeding to pump. It may be of the strangest coincidences that machine now doesn't operate after boom was manually lowered because I really don't think that would affect the suction side of pump. Did your aux pump operate machine prior to this incident?
hey willie59! yes sir..everything worked great.thats what has me stumped.the guy i bought it from turns wrenches for a living but were not having any luck
we can get fluid at the purge nipples when running the aux pump but not when just using the engine pump.also while running the aux pump sounds like there is air in there the way the tone changes when aux is being used
Well, I'm kinda stumped myself on this end as I'm not there seeing it, nor have I ever seen this happen. Those things are designed with those manual descent valves, should have no affect on system after resetting valves, that's what makes me think strange coincidence. One would simply have to go through system starting with pump to make sure it's delivering oil, then move on to the dump valves, etc
ok.i appreciate your time and will keep you updated
I just thought of this.when I brought the machine home is was super low on hydraulic fluid..as in probably a few inches from the bottom of the tank.we replaced the seal pack on the telecsoping ram and probly lost some more.machine still was working fine. After all that is when I realized there was not much fluid in the system and added some to reach the low mark.I then topped it off a couple days ago.I was wodering if you guys thought a dirty hydraulic filter could be causing this.I know what fluid was left before adding was dirty.just thought maybe I from adding that low to the tank it sloshed around some junk and possibly clogged the filter? Any thoughts?
Well, 40F, that's going back many years in my mind. The main filter is on the return circuit. I think the suction line does have a strainer on inlet inside the tank, but it would take a gawd awful pile of stuff to completely clog that strainer. If it were me, not having any idea what's going on, I would first disconnect line from pump to dump valve, drop hose from pump outlet into a bucket, and crank engine to see if it delivers oil, might even start it for a moment to make sure it has good flow. If it does, start going through the electrical and valving system.
Thanks willie! Yeah I did find when the hydraulic cap is removed there is a 1 inch tube about 4 to 6 inches down below the rim of the tank cap neck.if you remove one of the suction lines from the pump and pour fluid down the tube it will run out of the disconnected hose.the cap had a bad o ring Wich I will be replacing today and will go from there.thanks for your time and help
Yep, that's the suction strainer inside the tank, item #6. If that o-ring #8 doesn't make a good seal, it will draw air into the system and prevent pump from pulling oil through strainer. Could very well be your problem.
found the problem hopefully hey willie, thanks for the pic and your help.i found the problem.started by replacing the o ring on the cap and filled the tank full so it was above the suction tube.so we eliminated the air.cracked a couple lines on the pump and just wasnt pumping like it should. removed the pump and found the splines on the coupler were gone.i would have thought there would be a rubber or plastic coupler between the the pump and engine but i was wrong..its metal.so this machine has a metal splined coupler that connects to the flywheel witch bolts to the pump for those who want to know. can anyone take a wild guess at what the metal coupler will cost? just curios so i can sleep tonight..lol
I don't know what that would cost, been too many years since I've worked on those machines. Do you already have a JLG parts supplier you work with?
one other option is a replacement spline. Most bearing supply stores sell them. You buy a 3" or 4" peice of female spline your size, get your coupler on a lathe and cut out the old spline leaving a hole the right size to press in the new spline, weld and you're good to go.
Well we got the new coupler installed last night late and only had telescope,basket tilt and steer.no boom up down left or right.any suggestions what to check?
I take it drive doesn't operate either. Can you operate boom up/dwn or swing from lower controls?
hey willie, correct...no drive either.only have tilt basket,steer,in and out on both platform and ground
jay, I have to say, you have some of the strangest luck with this machine. LoL. My first guess would be a problem with the dump valve for proportional functions. Locate the hose that's connected to the inlet port of the proportional valve body and follow that hose back, should go to a solenoid valve body mounted behind the engine/pump, will possibly have two solenoid valves on it, one of those solenoid valves is the dump valve for proportional valves. When you operate boom up/dwn, swing, or drive, it should power up that dump valve coil.
ok..now that you say that we noticed while testing with the engine only running say...5 minutes that solenoid you just mentioned was warm almost hot.we were thinking of removing that valve tomorrow morning.also while the machine is running and you try to push the over ride pin in on that particular valve nothing happens.might just be the next problem solved hopefully edit: also confirmed good power at that solenoid.
Keep in mind there are several variations that JLG used in setting up the hyd systems on these machines. Assuming yours is as I described, and that you're certain you have identified the proportional dump valve, the only time that coil should have power is when you operate boom up/dwn, swing, or drive. If there is an additional solenoid valve on that solenoid valve assembly, I'm thinking that is for high drive. If you pushed the manual actuator pin in on dump valve coil while engine is running it wouldn't do anything, you would have to operate a function as well, either with a control or a manual actuator on that function. The proportional control valves (boom, swing, drive) and the bang valves (tele, platform rotate, steer) are both open center valves. I suppose, for the purpose of testing, you could re-plumb the hoses around the dump valve just to see if functions worked, but I'd be real careful doing that because I'm thinking the main relief valve is located in the dump valve assembly.
sounds good willie.i will discuss this with my help in the morning and will report back.thanks for your help and time!!
we cleaned the main racine porportional dump valve and still no drive,boom or swing.has anyone had to replace the seals inside the dump valve to get it to work? does anybody have any parts breakdown and fluid flow chart on this complete racine porportional valve assembly.also does anybody know what model/series of racine porportional valve that this machine has?we have determined we feel the pump is fine by switching pump outlets and the telescope,steer and basket still work the same on both outlets.thanks in advance!
a few pics
Jay, do you mind if I post your pics here at this thread? Makes it easier to reference them. Also, I'm considering changing the title of the thread to something like "need help with JLG 40FND problems". The thread has evolved beyond a bleeding issue, and since threads remain here indefinitely, the term "bleeding" implies to readers that there is such a method on these units. You ok with this?
Hey willie...you read my mind! I posted in a hurry.I was gonna suggest both fixin the pictures and renaming the thread.go for it boss!
Easy enough.
Oh man, so much stuff to cover. OFF is way more familiar with Racine proportional valves than I. The proportional dump valve doesn't really have seals on the control spool. There are o-rings that seal the mounting of the solenoid to the valve body, but no seal that would inhibit operation of dump valve. If you suspect the dump valve is your problem, do a temporary change in hose connections and take dump valve out of circuit, just to see if you get a reaction from operating proportional functions.
problem fixed hopefully A big thanks to Wille59 for all your help as well as everyone else who chimed in!! i got home today and said to myself i have to figure this thing out and i new it was something simple..and it was!! i removed the small high pressure filter and cleaned it just to see what would happen and everything took off.i don't know why i never checked this to start with but thats how you learn i guess. Pavel if you read this maybe check that.also i would start with the pump and move on to the next step such as dump valves etc... if you have a three stage pump try switching the two big outlet hoses and see if anything changes.that way you can rule the pump out wich is what we did.hope this helps thanks again Willie and all those who helped!
Good to hear you got it sorted out Jay. :drinkup