Hey guys, new to the forum here. Have found a lot of helpful tips throughout the years here so finally made an account. I just bought a 90's model 300D that has hydraulic issues, You have to idle the machine up for it to raise the loader or do any hydraulic functions other than steering and such. It's very sluggish and weak as it won't even pick up a half a bucket of dirt. I've checked the screen in the tank, Changed filters, topped off hydraulic fluid etc. I checked the pressure at the valve inside the right side step with the batteries. While warm and pulling the control to raise the backhoe boom as the manual states, The pressure is 1400-1500psi. Says it needs to be around 2850 psi if I'm not mistaking. Best I can tell I have the model with the non adjustable relief valve but not sure. Can't really figure out where its located other than the one in the front of the hydraulic pump. Was told there should be one on the priority valve. Any help would be greatly appreciated! Took the hydraulic pump off and apart looking for a blown seal but everything looks fine the best I can tell. Not sure how to test the relief valve in the front of it.
Welcome to HEF assfault . Whats the machine serial # ?
Serial number is T0300DA791572 thank you!!
The relief valve on the front pump (steering pump) is the steering relief valve. The main hydraulic system relief valve is located in the inlet section of the loader control valve. It is non adjustable. There is a seal kit (AT160684) available for the relief valve, I would suggest removing the relief valve and check for any blown o-rings. See screenshot below for relief valve location and part number. https://partscatalog.deere.com/jdrc/sidebyside/equipment/2658/referrer/navigation/pgId/2314749 . .
Thank you so much! I will check it out tomorrow and see what I can find out
I haven’t been able to locate the relief valve, I’m sure I’m looking right at it. Hard to tell anything in the pics but figured you may could tell me which one it is
The releif valve is located at the end of the inlet/ outlet section and the view is hidden by the pipe that I hilighted. .
I got it out. O rings seem to be fine. You can slightly see thru it which I’m assuming is normal?
This was what came out from the other end of the relief valve. Wasn’t sure if it was supposed to look like this or not. When I stuck the relief valve back in the other end it had a very slight spring feel to it. Wasn’t sure if it was supposed to be a stiff spring or very soft like mine. Thanks so much for the help! Sorry to make 2 posts I forgot to add this to the last one
Were you able to unscrew the top cap to take the relief valve apart ? is the poppet and spring in good condition ? I see the relief pressure setting is adjusted with shims. Maybe try a thick shim and see if the pressure reading increases at all. If pressure doesn’t increase I would flow test the main hydraulic pump OR disassemble the main hydraulic pump and check its condition.
I’m sorry to sound so dumb, but how does the relief valve come apart? I’m assuming the end screws off of it? Thank you so much for being so much help. You’re a lifesaver!
The top cap unscrews from the main body. See edited pic and screenshot below. . .
Spring looks fine. Everything looks fine in it as best as I can tell. I have the hydraulic pump off and apart. I don’t see any blown o rings or anything. Gears also look fine
Do you have the main hydraulic pump apart or just the steering pump? Maybe post some pics of the internals of the pump housing.
Post a pic of inside the housing that slides over the stud.
I’m sorry it’s taken me so long to get back on here. I ended up ordering a new pump for it and stuck it on and have plenty of pressure now. Checking it at the test port in the right side step it’s going over 3500psi when raising the boom past the relief valve. I took the 2 shims out of the relief valve and it’s still doing it. Any ideas? And the tilt on the loader bucket is stiff now.
As per the manual ,pressure test is to be done with hot oil. You are raising the backhoe boom only, correct ? I suspect at high idle you are flooding the main relief valve and getting a high pressure reading (spec is 2600-2850 psi.)To confirm flooding or not, try the same test but start at low idle and slowly increase the engine speed. The pressure should stay somewhat constant as the engine speed increases and then at some point the pressure will start rising due to flooding.
When you raise the boom all the way and pull the boom up lever by itself all the way back it’s just about maxing out my 4000psi gauge. Even at idle it’s going 3500+ I took the relief valve back apart and don’t see anything wrong with it. At low idle it kills the engine when you pull it back all the way. All the hydraulics get stiff/jerky feeling like it’s over pressurizing too. Hoping I didn’t mess something up by taking the valve looking thing directly across from the relief valve out. I thought it might’ve been another part of it but looked different so I put it back
Can you post a pic or hi-lite on an existing pic the “ valve looking thing directly across from the releif valve“ that you mentioned above.
This was it
Did you find this piece in the the same section that the main releif valve in was but at the opposite end ?
Yes sir that’s where it was
Is it the valve that I hi-lited in red in the pic below ? .
Yep, that’s it
That valve is not in the inlet / outlet section, it is in the valve section below, so has no bearing on the current over pressure issue.
Great. I just wanted to make sure, looked like it was the other end of the relief valve so I was afraid I messed something up
I suspect the previous owner jacked up the pressures (maybe on the priority valve) trying to cure the low pressure issue. Check the pressure when steering at full turn against the axle stop .should be 2450—2650 psi.
I will check that tomorrow and let you know! Thank you so much for the help! You’re awesome!
The new pump you put in came from Deere ? Is there a releif valve in the new pump similiar to the original pump ?
It actually came from a hydraulic parts/supplies company. It does have the same relief valve in the front of it just like the old one and is identical looking to the factory one