Hydraulic Issues on 4520

[TrustyRustyTractor]

We have a 4520 with syncro-range transmission.

The hydraulics started to chatter. I've been reading through some old posts here and it seems to be a common affliction that could have multiple causes.

I'm hoping to post the exact symptoms and everything we have done so far and maybe someone on here can help narrow the focus.

First, the hydraulics work beautifully upon initial start-up. But after the bucket loader gets raised up and down about a half a dozen times the arms start to slow down and things start to shake and chatter. The 3pt. arms will shutter too when you try lift them. Of course, push in the clutch, and as soon as the tranny pump stops pumping, everything comes to a dead stop - instantly, and nothing will even try to move at all until the clutch is let back out again.

Now, we've been on the phone with our local JD dealer mechanic/technician. We have cleaned and inspected all screens and the filter. As instructed, we removed the housing by the filter with the 4 valves in it and made sure they were free of debris and working properly.

Next, They made us do a simple transmission pump test by breaking the line leading to the front pump and turning the engine over. As soon as we releases the clutch, oil came flying out of the line and quickly and easily filled a 5 gallon pail in the time suggested.

So then, they told us, well your front pump must be shot, so we laid down 1200 bucks for a rebuilt one and spent a whole day installing it, but it still didn't solve the problem.

What else could it be? I've read in other posts of there being other "check valves" Where exactly are they?

I also should mention, that the remote the loader is plugged into was recently rebuilt, but the other remote is wore. It can leak badly (on and off) and there seems like there is always a lot of power/pressure going to it even though the console lever is in neutral. Could this alone cause the whole hydraulic system to fail?

Thanks for any insights.

 

[tim s]

I'm wondering if you have leakage in your loader valve,, remove the return line and head it into a bucket,, with the valves in nutrel there should be no oil going out the return line..

 

[Cliff Nelson]

Does the loader have it's own valve or are you using the tractor remotes to run the loader. It sounds like you are losing charge pressure to the front pump causing the pump to cavitate(chattering). This can be caused by a bad trans pump or plugged filters but more likely caused by an internal leak in the high pressure or return circuits. Best to put gauges on and test inlet pressure to determine for sure what is going on. If it will run for a while without cavitating, you can let it run and see if any valves get hot. A valve that gets hot fast is an indication of an internal leak.

 

[Tx Jim]

I agree with the others> What type valve controls the FEL?

 

[TrustyRustyTractor]

The loader is powered by one of the tractor's remotes, the one I mentioned has been recently rebuilt. We know the other remote is worn and has issues; It leaks out the backside of one of its outlets pretty good now and then but its been this way for at least 5 years.....Just for the heck of it, we switched the loader hoses over to the worn remote and it made absolutely no difference, one way or the other, in how the hydraulics preformed.

I am not sure where exactly the return lines are for these remotes, they don't seem to have any external lines going directly into them like our early 4020 does. I'm not entirely for sure they are going to prove to be the main culprit in the end anyway considering they've been the way they are for years.....

 

[Tx Jim]

I presume bucket is hyd so you must have an ind hyd valve. As Tim suggested remove tip from valve return hose and aim in hyd filler hole or bucket. With scv lever activated & both FEL valves in neutral no oil should flow out of return hose.

 

[D-]

PTO brake leaking?
Try with pto engaged.

 

[88 Diesel]

Just because your transmission pump filled a bucket with no load against it doesn't mean it can produce the correct flow when pressure is applied against it. I have also seen the square cover under the rockshaft cause an internal leak which will starve the system.

 

[DONMYEIL]

Cliff is on the money , you have a high pressure leak and when the oil cooler and reserve tank empty then the chatter begins . Check remote valves for getting hot and the steering valve as well .The rockshaft has a cover plate on the bottom that can leak . Look the plug hole , top right of the rear trany. case. see if there is oil flying around in there, should be none . If you have to remove the rockshaft hsng. I would replace the trans. pump. There is a larger pump available , get it .

 

[buickanddeere]

Problem always been there, gradual onset or sudden appearance?
This is a 1970's vintage 4520?
"Loader plugged into the remotes"? Is there two scv's in use, one lever for the boom and the other lever for the bucket?
Or is there a joystick/two valve control dedicated to the loader and mounted on the loader mast or something? With this dual loader valve supplied from one scv ?
Odds are the open center conversion valve in the loader joystick is blown. Or there is a relief valve in the loader control valve bypassing.

 

[TrustyRustyTractor]

Thanks for the insights so far.....The loader is a 720, and yes, it has it's own joystick. The two loader hoses are plugged into one of the tractor's remotes and we pull back on it's lever on the side console and hold it in place with a bungee cord.

We did just place this loader on the tractor this Spring but we don't feel the loader is the problem...We started to notice chattering in the 3pt arms last year. All we did with this tractor prior to the loader is plant corn and run a disc-bine mostly. When the hydraulic fluid would get down to the add line, we noticed a slight chatter in the hydraulics then too....So, thinking about it, I feel the problem was already there before the loader, its just that it's so much more pronounced now because a loader is more demanding on the system then say, raising a mower one time when you come to the end of a field. I suppose we could unplug the loader and plug in a implement and raise it up and down repeatedly and see what happens just to double check.

We tried working the loader up and down while the pto is engaged to test the pto valve theory, but that didn't help.

We've been looking thru the deere parts books online and are going to remove the pressure control valve tomorrow, thats under the dash behind the shift lever, and make sure thats working as it should. If that doesn't help, at this point, we are either going to get our own pressure gauge or just have a deere technician come down and test it.

If it does prove to be the transmission pump, we likely won't dig into the tractor that deep and may consider trading it off, which will bring me to my next post and question.....

In your guys opinion/experience, whats the best 4000 series JD to do loader work with? What transmission do you prefer and why?

 

[buickanddeere]

The 5045E can be had for less $$$ than a 4000 series. The 5000 series is a larger, more powerful tractor but alas lacks the hydrostatic transmission.

 

[TrustyRustyTractor]

Um Thanks, but I guess I should clarify our 4520 is the 1970 , 125hp version, and it's main loader task will be to push up and pack down our feed stack

 

[buickanddeere]

In your guys opinion/experience, whats the best 4000 series JD to do loader work with?

4 or 4000 series is the hydrostatic utility tractor. What model are you thinking of ?

 

[Tx Jim]

(quoted from post at 22:57:31 05/04/14)

In your guys opinion/experience, whats the best 4000 series JD to do loader work with? What transmission do you prefer and why?

I think a 30 or 40 series such as a 4230/4240 with a quad range or powershift trans would be a good replacement for a 4520 to install the 720 loader plus you'd get a 540/1000 rpm pto shaft. On the 30 & 40 series the trans pump turns all the while engine is running.