"Screeching" sound

JMER817 · Apr 7, 2015

2013 John Deere 4120 I'm getting a "screeching" sound in the front when under heavy load such as coming in to a pile of dirt with the loader. Sounds possibly like the hydro relief valve? I can get it to do it as well when I do a hard acceleration in high gear such as the example in the video

https://youtu.be/ofClk2D1iMI

Sysop · Apr 7, 2015

Hydro-fluid levels right in the axle? Fluid been changed according to recommendations?

Ken · Apr 7, 2015

Could be the Hydraulic filter needing replaced Have a 4520 and when under load gets whinny and change filter quiets it down.
ken

JMER817 · Apr 7, 2015

All fluids and filters have been recently changed

Code54 · Apr 7, 2015

Sounds like you are kicking the relief valve in

Billrog · Apr 7, 2015

Doesn't sound like a relief valve to me ( I could be wrong) but more like it's torching something in such a way it rubbing when you go into the pile.

JMER817 · Apr 7, 2015

Code54 said:
Sounds like you are kicking the relief valve in

Any way to adjust the valve?

Code54 · Apr 8, 2015

Sorry my bad - I played the video on my Macbook and can hear it 100x better and have to agree - not the relief valve. Sounds more like metal on metal. Check your pins, loader bolts, really every major component to make sure no bolts are backing out on the machine and causing movement and then the noise.

skyhook · Apr 9, 2015

The revs of the engine seem to lower indicating the relief is kicking in but i don't believe it has anything to do with the relief, could be something with your fan belt or tensioner for it if you have one.
Maybe needs grease somewhere along the loader area also.

Gator6x4 · Apr 10, 2015

JMER817 said:
Any way to adjust the valve?

Look over the front end and see if you can see something that is loose. Open the hood and look at the radiator fan and housing. Check and insure everything is tight. Check and see if you can determine what could be shifting when the loader is down and being forced backwards by driving into the dirt pile.

arlen4720 · Apr 10, 2015

It is absolutely the relief valve. That's the way they sound. I was surprised too when mine first did it. They crack open at almost 5500 psi so it has a different sound than a typical 2500psi hydro relief. I don't believe that they are adjustable...At least there is no mention in the service manual about it. There are test ports to check the pressure with a 10,000 PSI gauge.
The procedure to check it is to put it in C range, then set the parking brake, rev to full throttle, then push the pedal. It should screech, and you take your reading. Repeat for reverse (2 separate relief valves, 2 test ports)

Are you in C range when you are doing this? I have a real hard time making mine relieve in B range, and darn near impossible in A range, but it will relieve at the drop of a hat in C range.

Sysop · Apr 10, 2015

He said the video example was in high gear, you may be onto something. :thumbsup:

JMER817 · Apr 10, 2015

Yes C Range. Do you have a 4000 series John Deere? I had an older 4310 (same as 3320 now) and also rented a 3320. Neither of them did this.

andy1981 · Apr 10, 2015

I have 2 4720's they both do this and have since they were new, it's usually in high gear with a heavy load going up a hill, or starting out when I should be in mid range

arlen4720 · Apr 11, 2015

JMER817 said:
Yes C Range. Do you have a 4000 series John Deere? I had an older 4310 (same as 3320 now) and also rented a 3320. Neither of them did this.

Yes , I have a 4720, which probably would do it worse than yours because it has more power to overwhelm the relief valve.
In my opinion, C range is not for doing any useful work, just transporting.

You could check the pressures if you think they may be weak. I did have the dealer check mine, and they were fine.

JMER817 · Nov 6, 2015

Update,

Dealer found hydro pressure to be at 3200psi from the factory. Spec is 2500psi. Checked and adjusted under warranty. No more screeching.

arlen4720 · Nov 7, 2015

JMER817 said:
Update,

Dealer found hydro pressure to be at 3200psi from the factory. Spec is 2500psi. Checked and adjusted under warranty. No more screeching.

Which pressure? The implement circuit is supposed to be 2500, but that doesn't have anything to do with the hydro tranny. The tranny circuit itself is set north of 5000psi.