Update on JD310A backhoe

[onalaskahoe]

Hello all

My John Deere 310A backhoe has slow and weak hydraulics, the machine moves fine in both forward and reverse, and the steering is pulsy. Even with the RPM up over 2100 I still have slow and weak hydraulics. I have done the following and I will list the results.

1) Replaced the Hydraulic filter.
2) Replaced the Trans filter.
3) Removed and cleaned and replaced the Hydraulic intake screen. (There was very little dirt on the screen).
4) Removed the Hydraulic filter mount and checked the relief valve, it looked good.
5) Checked radial pump and pistons look great and o-rings look good and closed back up.
6) Replaced STROKE control valve.
7) Replaced system fluid with new fluid.

Now!!
The machine still has slow and weak hydraulics and with high RPM, but I did see today that after rising the loader I find that as I let it down I can hear the pump load the engine a little and if I stop and quickly use any operation of the hoe it has strong and fast action. This only last for a moment but if I use the stabilizers they will lift the machine right up off the ground and if I have the hoe straight out and on the ground, I can lift it right up fast and strong. And the loader is still slow and weak but if I let it down and the motor loads I can then at bottom use the down force and lift the front of the machine right off the ground.

So now my question is? Is there a bypass or something that I have mist that can cause this?

I have not checked the bypass for the Trans filter, and I have not yet checked the charge pressure to the hydraulic pump but with the trans forward and reverse working I thought that would show a good charge pump.

And when I check the trans pump pressure should I check on the hydraulic pump at top or bottom of the pump head ports. And for the reverser do I check at the plug on the back that is facing down?

 

[Hillbilly-tn]

your pump housing is worn and bypassing oil destorking
the pump. get new pump.

 

[onalaskahoe]

what pump? main or charge?
And how can you tell?

 

[Jonathan in MA]

Put a pressure gauge in the top port on the stroke control valve. I'm assuming by what you said that it has two ports on the right side, one above the other? The top port is the high pressure output pressure.The lower port is the charge pressure. The standby pressure at the top port should be around 2300 +/- .. If its not, get a JIC cap and plug that fits the output fitting on the pump. I believe its #12 (3/4") but don't hold me to it. Block the tube either at the pump or at the first tee fitting where the steering line tees off of it. You can dead-end the line without hurting anything.(closed center system). Then see if the pressure comes up to spec. This will tell you if the pump is capable of building pressure or if its feeding a big leak downstream and cant keep up with it..If the pressure is good with the line capped, then reconnect it and start eliminating things downstream one at a time. Start by blocking the steering pressure line. Then block the backhoe line where it exits out the back of the pressure control valve. (priority valve) . Thats pipe thread on that hose , so it may be easier to get a cap that fits on the end of the hose where it enters the backhoe valve. Blocking off the loader valve may be tough as I believe its all steel tubing that feeds that. Could be dumping through the pressure control valve also I believe.. Do you have a book so you can follow the route the pressure oil takes??

 

[T. G. [GA]]

Check the relief valve next to the backhoe filter. this filter is up-right and to the right rear of the tractor. The relief valve is the hex plug next to the filter housing. remove plug and relief valve should be there. I had a JD 310a that was slow and that valve was missing. Installed a valve and it worked okay. i think someone was changing the oil and thought that was a drain plug.

 

[Hillbilly-tn]

main pump. you will find one piston lose. the bottom of
the pistons where they ride on cam will be wore and
cam bearing will be locking up with steel in it. you can
play with the hydraulics and when you get hoe moving
keep lever wide open it will work ok till you slow
down or stop than it will quit. my 410c did that and it
took me twe days to find it.

 

[onalaskahoe]

Yes I do have a book, and I forgot to say that the charge pump was replaced about 30 hours ago as well as the primery hydraulic pump, by the last owner.

Tomorrow I will check the trans bypass valve, someone told me that this valve could cause this issue. I will also see if the charge tube to the pump has a bad hose where it joins under the engine, this may be restricting flow and causing the slow and weak issue.

Please continue to talk with me about any thing that i should still check.

I will try to get the pressure of the charge port on the pump tomorrow.

 

[onalaskahoe]

Yes I do have a book, and I forgot to say that the charge pump was replaced about 30 hours ago as well as the primery hydraulic pump, by the last owner.

Tomorrow I will check the trans bypass valve, someone told me that this valve could cause this issue. I will also see if the charge tube to the pump has a bad hose where it joins under the engine, this may be restricting flow and causing the slow and weak issue.

Please continue to talk with me about any thing that i should still check.

I will try to get the pressure of the charge port on the pump tomorrow.

 

[Mike M]

That must be a kinda common problem ? As I went to look at a 410 ? for sale once and the hoe worked,but the loader was really slow and jumpy. upon questioning the owner then showed me a plunger and a spring and asked if this may have anything to do with it ? It came out when they were guessing where stuff was. I said it has to of been in there for a reason. I said the heck with this one for this and other reasons.

 

[John Heine]

DOES TRACTOR HAVE ELECTRIC DESTOKE VALVE? HAVE SEEN THEM STUCK PART WY OPEN.CHECK FLOW TO MAIN PUMP FROM TRANS. PUMP.

 

[onalaskahoe]

Yes it does have an electric de-stroke valve, I have looked at it and it looks to be closed.

If this is leaking under pressure would it cause these symptoms?

 

[Anonymous-0]

I had the same symptoms on my 300 backhoe, including the jerky steering. You should follow the excellent advise of Jonathan in MA. I believe you should put a gauge on the reverser (look for 140 psi in forward and reverse) and the top port of the main pump.

In my case, I had two problems:
1. the clutch pedal cross shaft to the reverser has a roll pin that connects it to the reverser valve. It had worked itself loose and was preventing the reverser clutch valve from closing thereby starving the main pump.

2. My steering valve was shot, and all the oil was bypassing back to the tranny. You can test for this. It is easy to cap off the line to the steering valve to eliminate this as a possibility.

Richard

 

[onalaskahoe]

Thank you to everyone, I will be ordering a test kit for the hydraulics to look for the 150psi at the charge side.

I will also be checking the isolation of the steering valve.

I will update when I do.

Chris

 

[Roy Suomi]

With the gauge on the charge oil port , run the engine up and down..Wide open to idle...Does it have a large variation in pressures ?? If so , It's probably the filter relief valve in the side of the trans case just above the vertical filter...It doesn't take much to make it not work..Just a teeny tiny particle will hold that valve slightly open..The valve should be moveable with a screwdriver..Pay particular attention where the poppet valve is before the screw driver actuation and after..

 

[buickanddeere]

Is there any flow from the loader"s control valves and/or power steering back to the "sump" when no hydraulic functions are being requested?

 

[onalaskahoe]

How would I check that without a flow meter?

 

[buickanddeere]

Don"t need a flow meter,there should be no flow.
Any flow through a closed center valve when a function isn"t being call for. Means the valve has failed.