To be honest I am not a John Deere man, but replied based on my experience with both open and closed hydraulic systems I have dealt with over the years.
A 4020 may have more than one pressure regulator valve governing seperate parts of the hydraulic system.
It sounds like when you aren't diverting part of the pumps output by using the hydraulics that is when you hear the noise.
It might also stop the noise if you were to connect a remote cylinder to one one set of your remote ports and then move the cylinder which would also divert some of the flow momentarily stopping the noise.
I assume the noise is worse at only certain RPMs and is most likely the worst at near idle ??
I would think that somewhere the spool, the spool bore or both, might be slightly worn.
Hydraulic fluid, like water, is not really very compressible and when the gears in a hydraulic gear pump are pushing against high pressure it creates tiny pulses that resonate through the hydraulic system.
Every hydraulic system has a certain resonant "sympathetic" frequency at which the pump pulsations will create noise and vibration much worse than at a RPM that is slightly higher or lower than the resonant frequency.
Every hydraulic system is different and some don't seem to be noisy at all and others sound like they are about to shake themselves apart.
When you divert a portion of the flow causing a momentary slight drop in pressure the pressure regulating valve stops having to regulate and the noise stops.
Where the valve is I don't know, but that is where I would start.
We sell tractor parts! We have the parts you need to repair your tractor - the right parts. Our low prices and years of research make us your best choice when you need parts. Shop Online Today. [ About Us ]
Today's Featured Article - The Fordson F Ignition System - by Anthony West. A fellow restorer contacted me earlier this year asking for some help and advice on a model F that he was restoring. He had over a period of months spent a fair amount of his hard earned cash on replacement parts for the old "trembler" ignition. Sadly though all his efforts seemed to be a waste of time and money as he still couldn''t get the temperamental old thing to run correctly!! If i said that this was a little frustrating for him that would be "conservative" in fact the problem had reduce
... [Read Article]
Latest Ad:
1964 I-H 140 tractor with cultivators and sidedresser. Starts and runs good. Asking 2650. CALL RON AT 502-319-1952
[More Ads]
All Rights Reserved. Reproduction of any part of this website, including design and content, without written permission is strictly prohibited. Trade Marks and Trade Names contained and used in this Website are those of others, and are used in this Website in a descriptive sense to refer to the products of others. Use of this Web site constitutes acceptance of our User Agreement and Privacy Policy
TRADEMARK DISCLAIMER: Tradenames and Trademarks referred to within Yesterday's Tractor Co. products and within the Yesterday's Tractor Co. websites are the property of their respective trademark holders. None of these trademark holders are affiliated with Yesterday's Tractor Co., our products, or our website nor are we sponsored by them. John Deere and its logos are the registered trademarks of the John Deere Corporation. Agco, Agco Allis, White, Massey Ferguson and their logos are the registered trademarks of AGCO Corporation. Case, Case-IH, Farmall, International Harvester, New Holland and their logos are registered trademarks of CNH Global N.V.
