7020 Hydraulics

Bill in IL

Well-known Member
I have been having some troubles with the 7020 hydraulics lately. It has been on the batwing and has trouble lifting the mower. It struggles to lift the mower I think due to air in the system cause some times it will go down before it goes up other times it is just slow till it can work through the air and finally lift. The hydraulic fluid in the rear end has small air bubbles in it as well. System is over full at this time cause I added fluid thinking it was low due to the air bubble in the sight glass. Yesterday I topped off fluid and headed out to mow. Hydraulics acted normal at first then it was gradually back to the normal air in system indications I had before. Are there common hydraulic problems with these that can cause it to suck air? Is there a suction filter on this tractor?
 
Overfull can cause whipping of the oil. This puts air in the oil giving the symptoms you describe. Overnight the air will leave the oil and as you run it it will be whipped back in. Let it set overnight, then drain to the proper level. Probably will fix it.
AaronSEIA
 
Since you're asking about filters, I must assume they haven't been changed recently. There are two, one in each side of the differential housing. The suction being the one on the left side.
 
I recently had an air in the oil, problem, and after extensive work, and not finding it, I noticed where the Previous owner, had added a female quick disconnect, to the suction hose, just before it got to the pump. I replaced the quick disconnect, with a 3/4" pipe plug, bled the system, and all was good. The pump suction, was slightly opening the valve on the quick disconnect, and introducing air to the system!
 
i had trouble with my 7020 lifting, at one time. they told me to check the pressure. when i did it was 2200lbs. usually want it at 2500. my dealer sold me some parts to get it to 2500. has worked great ever since.
 
That particular generation of hydraulic system has a setting called "stand-by" pressure. From the symptoms described, it sounds like that number is lower than spec. It is checked at the "tee" fitting on the side of the PTO valve. Stand-by pressure should be 350 psi MINIMUM and when I reset one, I shoot for 600 psi. You add small shims to the small spool compensator on the main hydraulic pump to raise the pressure. While you have the 3,000 psi gauge connected to the tee, pull on one of the hydraulic levers and make the pump groan. You should have 24-2500 psi full pressure setting. Make sure your hydraulic levers aren't loose, as the linkage under the seat wears and won't fully stroke the spool to the lift position and can cause issues like this too. The entire hydraulic system depends on clean and correct spec'd filters underneath the rear end housing. Those air bubbles you see are nothing to worry about. Real air in the hydraulic system causes the steering to act jerky, which you say nothing about, so I assume there isn't a problem with that.
 

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