We have 621 F that is just out of warranty, used on a dairy every day, so relatively easy use. However if it begins to get warm, it will make a noise similar to engaging park break on a skid steer. Then we lose lift and steering, machine will still drive, but sounds like it may be straining for oil. If we fiddle with joystick, and manage to get lift to come down, we regain hydraulics, otherwise we have to turn off machine, and let it sit for a while. We had the dealer come out, but all they wanted is to haul it to dealership. We believe as new as the machine is, it is a simple problem. The heat guage fluctuates a little also, and there is a low level buzz, but I don't think these problems are all related. If we take it easy, we can manage to run without losing hydraulics. It seems to be worse in warmer weather. We had a service agreement until recently, so maintenance should be up to par.
You may have a bad ground at cab to frame.
Serial number?
nff232843 is serial numer. Thanks for the thoughts, I am confident someone has dealt with this issue...
Sounds to me like a load sense issue. The pumps will not deliver oil until an ls signal is received. Ls from steering and loader system are connected at the steering priority valve. Id start there and check for LS once it acts up
That makes sense, because getting steering in a bit of a bind will cause the problem also. would it work to just change the sensor?
I have been dealing with a similar issue on a 621D. My problems were only occurring at temps below 10 deg F. I'm pretty sure the hydraulic pump was just starving for oil. We drained the hydraulic oil and replaced it with hytran. Also replaced the filter. I also opened the access cover on the tank to check the suction screen. The screen was not plugged but i removed it anyway and blew off a very small amount of debris. I delt with this problem for a long time because the dealer told me that there was no section screen. So in my mind I felt that since the pump is fed with a 2"? line it could not actually be starving for oil. Im pretty sure that in really cold temps the oil was just too thick to pass through the screen. I have only owned this machine for about a year so I have no idea what oil it had in it when I purchased it. It has been operating fine so far but we have not had any really cold temps since the fluid change to know for sure. Good Luck!
Ok, We have had mechanic out, and we have more info. The pilot pressure is 500. The loader lift on the valve bank is 900 to 1000. It trips at 900, sometimes lower. We are wondering if it is the check valves between the steering and the lift. But where are they located? It operates fine, until the oil warms up to 154 degrees, then it is hardly usable. Any input is appreciated! Thanks in advance...
We have 1000 psi at the compensator valve when it is acting up as well.
mechanic has narrowed it down to losing charge pressure to the variable piston hydraulic pump, and the main pump is good, we cannot get any help from CASE. dealer is too busy, and no help from corporate tech support
My experience is does not cover the F models. However, I looked up the pump and of course case does not show details of the pump. It does show the suction line going straight to the pump. I don't believe you have a charge pump. I only see the brake pump and the main pump. Loosing pressure as the oil heats is indicative of pump internal leakage. How do you know that the main pump is good?
I believe I have a fairly sharp mechanic working on it. I wouldn't mind if you gave him a call if you know something. But he has confirmed the main pump is good, I am not sure how, and he actually said the oil is not getting hot or excessively warm. It makes me think it may be a suction issue, which he has checked, or maybe some other issue such as pressure of some kind, or a sensor getting warm, etc. It does not slowly lose pressure, it clicks, and its gone, and by wiggling the bucket down, it will go again as it relieves the pressure or something. It may be something like a solenoid malfunctioning, but where to look, thats why I need help. It has been broke down for a year, and the payment continues to roll around every month. It does whine when it loses it, as the pump is starving for oil, and the quick attach on the loader still works, obviously a different circuit...
I was not questioning your mechanic necessarily. Typically only hydrostatic loops systems and radial piston pumps use a charge pump. You have neither. 900 psi is not nearly enough pressure to work the boom. Ask your mechanic if he could perform a case drain test on the pump when cold ,then when it is warm and acting up. Pictures of the pump might help.
I don't know if we have a charge pump, but we need pressure from somewhere to feed the variable piston pump. It has one of those right? A couple ppl have mentioned it could be a load sense issue... if the pump is not being told to pump, we will have no pressure... The lines over the front axle seemed to jump when it triggers, but it is hard to pinpoint exactly where the trigger is.
I tried to look it up on the case parts lookup but it does not show a breakdown if the pump so I am only assuming your machine has a variable piston pump which does not need a charge pump . The case drain test will tell you what the condition of your pump is. And you might just have a load sense issue, but with out hands on the machine I am just speculating and trying to help out.
Well I know its above my level of intelligence! But I think if someone was willing to walk through a few steps to narrow down the diagnosis we could get to the bottom of it... But if I understand correctly, we are losing charge pressure, so if there is no pump, then somewhere(load sense probably) is not telling something to pump. So here is a question. Does load sense tell the variable piston pump to pump? Or is it responsible for charge pressure? I appreciate the help! Thanks
If I'm not mistaken the hyd. pump is a vain style pump and not a piston pump. Of course that could be different sense I worked on the "D" and "E" series loaders. Check your main relief valve in loader control valve, and flow meter your pump to make sure it is working.
It acts like a relief valve, which we have checked and even swapped and bought a couple new. I think it was the main relief we swapped. The pump does starve for oil right after it pops, and I think we have checked the flow as well. Everything functions perfectly, until it suddenly triggers and its over. Its like something is diverting the oil away from the pump that supplies the functions. If I understand correctly, the main pump pumps all the time. So there are two pumps.
Mechanic has determined it is not mechanical. Something is causing it to dump the oil back to the tank when it is not supposed to, we think it is related to it running a while as in it may get warm as it runs, such as a sensor getting warm, because it runs longer when it's cold.
Beef farmer i was just wondering if you ever found out what was the cause of your hydraulic issues you experienced with your 621f loader as mine started doing the same thing today word for word as to what yours did. Thanks for any help on this.