John deere 4010 hydraulic problem

My son has a 1961 4010 and the hydraulics seem really slow to me. Also the 3 point seems to jump up and down as it goes up. It seems to steer pretty good and the brakes work good. The hydraulic pump does seem to make some noise, almost a knocking sound. We put on a new rubber flex coupling that drives the front pump but this didn't help it.We capped off the line coming from the front pump and it does have good pressure but the needle fluctuates real fast. We plowed with it and planted soybeans but it seems to lift slow. Also the steering will stop working when you are lifting a plow or planter. We took what looks like the priority valve apart and there is absolutely nothing inside of there but oil. Its just an oil manifold basically. I have been told that the real early 4010s didn't have a priority valve. Is this true?

We want to fix the hydraulics this winter and I am wondering where to start. I think we need to rebuild the front pump. This pump is original as the destroking valve is on the bottom where the newer ones are on the top. Are parts available for this old pump? Also if the transmission pump is bad will it cause the pressure gauge hooked to the front pump to fluctuate real fast like this one does?

Jim, the first thing you need to do is get a genuine DEERE shop manual, and follow the troubleshooting flow charts.

Typically, the genuine manuals have color-coded hydraulic diagrams and the aftermarket copies reduce them to black and white, making understanding how the hydraulic system works a lot harder. (I can't remember for sure if the color charts go all the way back to the 4010, tho.)

You will need a "FlowRater" of some sort to do some of the tests.

NO reason to throw $$$$ at it without finding out what's actually wrong.

NOT sure what the very first tractors may have used, but www.jdparts.com shows 4 versions of the "pressure control valve" all with a spool and springs inside.

Plug your gauge into a rear coupler. By just cracking the control lever you can get a
pressure reading without the needle vibrating. The vibration is normal every piston stroke
of the pump make the needle vibrate.

I would make sure the stroke control is set for 2250 PSI and all filters are cleaned out first.

To my knowledge all JD 4010s had a priority valve. I would bet that yours has a hydraulic pressure or flow problem and someone just remove the internal parts of the priority valve. I have bought several JD tractors over the years that have had this done.

Also spend the money and get the JD service manual for your tractor. SM2039 is the one you need. They can be bought for around $100.

Also NEVER dead head the hydraulic system like you did. You can damage the hydraulic system that way. All you need to do is put a gauge in the rear SCV port. No bouncing and much easier to do.

I will bet that you have low pressure/flow when the lift or SCVs are used. This caused the priority valve to shift. Therefore shutting the external hydraulic off. So you need to figure out what is wrong before even trying to buy parts. It could be as simple as a three point valve leaking internal.

If the priority valve has been disabled than that is what I would fix first. This is a major safety issue. You can lose brakes and steering running it like it is.

(quoted from post at 22:36:51 10/28/17) To my knowledge all JD 4010s had a priority valve. I would bet that yours has a hydraulic pressure or flow problem and someone just remove the internal parts of the priority valve.



Also NEVER dead head the hydraulic system like you did. You can damage the hydraulic system that way.



If the priority valve has been disabled than that is what I would fix first. This is a major safety issue. You can lose brakes and steering running it like it is.

Click to expand...

I agree that someone must have removed the internal valve in the pressure control valve & it's very important to re-install the parts for ""safety reasons"".

I see no reason why a closed-center hyd system such as the 4010 shouldn't be "dead headed" because when one dead heads it then hyd pump is designed to go out of stroke therefore pressure can't rise any more. When one installs a gauge in breakaway coupler to check stand-by pressure or fully extend/retract a cylinder one is dead heading the hyd system for a short period of time.

We did check the pressure a while ago at the scv and it was at 2250 but it still had the pulses. That's when we capped the pressure line from the pump to check the pressure there to isolate any internal leaks in the rest of the system. Using the 3 point or the scv causes the pump to make more noise king of like a clattering noise. It almost sounds like the front pump is starving for oil. We did change the filter and check the screen in the transmission and it looks fine. I have heard of leaks on the suction side of the transmission pump that causes the transmission pump to suck air.

Here is a picture of the priority valve in this tractor. It just doesn't look like any of the ones on jdparts website. I don't know what the priority valve should look like inside but this one just has a hole drilled through long ways and another hole drilled crossways. there is no seat or spring or anything inside. I read where these early tractors had no priority valve and john deere updated them later but I am just wondering if this tractor was never updated. This tractor has the light axle housings like the very first 4010s had and this tractor has very low hours. It still has the original 24 volt system. If I were to guess, this tractor has less than 3000 hours.

What he needs to do is to call me after while and I will walk him through the test. There could be a combination
of issues here, if the priority valve sleeve has been removed it could leak out the small line on the back,,if the
trans pump is worn out the front pump will cavitation, if the front pump has a couple pistons stuck or broken
this will give that problem, if the stroke valve is stuck it will act this way too. Dead heading
get this pump will not hurt it, and if it is the original pump I would replace it with an after market new one,you
will have near as much Inn rebuilding an old pump as a new after market one cost.

When one installs a gauge in breakaway coupler to check stand-by pressure or fully extend/retract a cylinder one is dead heading the hyd system for a short period of time.[/quote]


The jd system being closed center- constant pressure; it is dead ended in rest mode.

Closed center = 0 flow full pressure at rest
Open center = full flow 0 pressure at rest
Pressure and flow compensated (allis 7000 series first) = 0 flow and reduced pressure like 250 PSI at rest.
If a tractor had 0 leaks anywhere and no hydraulics functions are used; the only flow out of the pump is for the priority valve bleed line, which is very small flow.