John Deere 2720 No PT0 No Power Steering....No Clue

[smashedtoe]

Hello once again friends.

Okay I am faced with another issue with my JD 2720 and I am looking for some advice.....and no, not the advice which suggests a different colour tractor, etc.

This past winter during an extreme cold snap (-42C) my son wanted to be helpful and clear some snow. He started the 2720 but only let it warm up for about five minutes.

After placing the tractor in reverse and attempting to back out of the shelter, the tractor quit moving and steering wouldn’t turn.

Is it possible for a seal in the power steering ram to blow and the hydraulic oil is essentially working against itself in the system? The tractor moves slowly but you can hear the pump strain but the hydrostatic pedal needs to be pressed fully downward. Power steering doesn’t work, however, if you continue to turn the steering wheel the pressure seems to build and the wheels actually turn - one way more than the other.

Absolutely zero PTO when it is engaged and the oil on the rear sight glass does not seem to lower when tractor is running.

I am not sure if the main hydraulic pump is burned out or what to test for. Any suggestions?

My loader hydraulics work just fine as this is controlled by a separate pump.

Thanks in advance

Jeff

 

[Will S]

What's the fluid level and color look like in the PS pump?

 

[smashedtoe]

There is no power steering pump on this tractor. I believe the main hydraulic pump supplies the oil to the hydraulic cylinder for steering.

I struggle to believe it’s the main pump, but am unsure how to validate.

 

[LouNY]

Quite often there are two sections in the hydraulic pumps with one section for the loader, remote hydraulic and 3 point;
the other section is for power steering and pto clutch operation and as a charge pump for the hydrostactic pump.

 

[smashedtoe]

Is there any way to test the system to confirm where the problem is?

 

[smashedtoe]

I finally committed myself to tearing this down and discovered the inner and outer rotors in the charge pump, along with a sheared key way were the source of the problem.

I am hoping to find a hydraulic pump manufacturer will have the replacement rotors as opposed to buying a new pump for $1,000+ CAD. If anyone here has a suggestion on who I may contact please let me know!

 

[Dwellonroof]

I finally committed myself to tearing this down and discovered the inner and outer rotors in the charge pump, along with a sheared key way were the source of the problem.

I am hoping to find a hydraulic pump manufacturer will have the replacement rotors as opposed to buying a new pump for $1,000+ CAD. If anyone here has a suggestion on who I may contact please let me know!

You might reach out to Hydrosplus he might be able to help you.

 

[smashedtoe]

Quite often there are two sections in the hydraulic pumps with one section for the loader, remote hydraulic and 3 point;
the other section is for power steering and pto clutch operation and as a charge pump for the hydrostactic pump.

Hey LouNy. So it ended up being the charge pump which we replaced. PTO works great, however, the power steering really seems spongy and almost non-responsive.....unless I engage the PTO. With the PTO engaged the steering improves slightly but the hydrostatic drive whines a little more. Suspecting a faulty relief valve? Any suggestions as you seem to know what you are talking about!

Thank you.

 

[LouNY]

Not familiar enough with your Deere's hydraulic plumbing to say for sure on many tractors the charge or low pressure system does many of the functions of the tractor operation. Including the make up oil for the hydrostatic pump, the PTO opertion and the cooling loop and transmission lube function. I believe that your system is an open center one and I thought it had a dedicated pump for steering, that loop could have had something happen to stick a relief valve open. A service manual should have a flow diagram for the different hydraulic circuits.

 

[oldnslo]

A typical circuit would have the PTO being fed via an orifice and either pressure reducing or relief valve to limit PTO circuit pressure. Next would be steering with a system relief for steering. Steering flow then may go through cooler or may feed charge circuit for HST. If you have shuttle shift it would most likely also be supplied by this curcuit.

Since pump was trashed possibly contaminates were forced through that circuit causing valves to stick.