JD 400 Backhoe pulsating weak hydraulics

[JimmyBOD]

I have a JD 400 built in 1966 and it has run fine until lately. The JD dealer has cleaned the sludge screen filter and installed all new filters in the hydraulic lines. The dealer thought the machine was running correctly when I picked it up but when I tried the hoe and the bucket the pulsating hydraulics along with weak power was still prevalent. The transmission, power reverse, power steering and brakes all work fine. The JD dealer wants me to take apart the Pressure Control Valve and look for problems. I see the trans, a box next to it that is probably the reverse box and next to that a housing for the brakes. Can't find the pressure control valve on this unit that matches the pictures from the manual.
When the tractor is running, the tank above the pump, AR101807, has fluid in it. The dealer did not take any pressure or flow measurements in the pump when it was in the shop. It has been 10 years since the pump was rebuilt. Any clues of what to do next to remedy the pulsation and get the power back?

 

[olde man]

there could still be some sludge lurking around in your pressure controls,pending on how bad things were you may have picked up more in your screen. on your pump you have a destroking valve in the end cap of the pump that can get clogged causing chatter. you should have a relief valve in your control valve near the inlet. these parts are sensitive and close attention needs to be paid when inspecting them. I don't know for sure if your model has one but jd used to use an auxillary pump also it may be cavitating as well.

 

[JimmyBOD]

Thanks for the tips. When the tractor was at its worst, the JD tractor mechanics worked at cleaning filters and the sludge screen. They filtered the old oil and put it back the tractor. I removed all the oil and rescreened it. I did find some dirt/sludge in the oil they put back in. (?) I still can't find relief valves. The tractor mechanic asked me if the loader had a single joystick. it does. I dont know why he needed to know that.

 

[J_J]

Your joystick valve probably has a relief valve close to the IN port.

Can you show a picture of the joystick valve especially the top of the valve.

 

[JimmyBOD]

J_J:

I have attached a jpeg of the view I think you asked for. If not, I have more of the hydraulic lines and parts. The hoses on the left are the in and out (?) and the other goe to the cylynders. I guess. JimmyBOD

 

[Taylortractornut]

Sounds like the pump. If its what I think it is its an Oil Gear pump. THey are a radial piston pump and has pugs and pistons around the outside of the pump. We had this happen at work on one of the JD scrapers. One pump had a worn piston and had good presure till that cylinder and one had an egg shaped bore. Kintec remans these pumps.

 

[JimmyBOD]

Thanks Taylortractonut:

It does have a spline pump, AR101807. I have talked to Jerry at Kintech about his pumps. What worries me about him is I googled his address and it showed up as a road in a forest in Missouri with no building in sight. A&I sells the same reman about $300 more.

I have about half of the tractor mechanics focusing on control valves and dirty fluid and filters, and a few focusing in the main pump. Some maintain it is the pump in the trans but the tractor moves, steers and reverses and has brakes.

 

[J_J]

Here is an example of a relief valve.

http://www.surpluscenter.com/MorePhotos.asp?ITEM=9-7862-F

 

[JimmyBOD]

J.J:

Thanks for the picture of a relief valve. Tommorow I'll get out and under looking for a valve and taking pictures. My manual is for a 2040. The pressure control valve in the 2040 manual does not exist on my tractor.

If I find something that might be a relief valve, should I open it up to check for worn parts, bushings and dirt?

The hydraulics failed slowly and over a week or so there wasn't much left that didn't shake. I am assuming that comes from the main pump. It is not working correctly (worn) or is cavitating because it isn't getting enough oil. Is that it?

JimmyBOD

 

[olde man]

look at a 2020 they're closely related