JD2040

[turftech1]

Hello, I have a 2040 JD that started to make a chattering noise in the hydraulic when you lift the 3 point and also the steering and 3 point do not work properly. First off I drained the hydraulic oil, pulled out the suction screen and cleaned (wasn't dirty at all), replaced the filter and refilled the system with new hyd oil. I noticed that the oil was foamy like air in it from cavitation. I checked the lines and fittings and pulled all the relief valves out and inspected, cleaned and re-installed them(all good). I pulled the hyd pump off front of tactor. I dissassembled pump and inspected (looked good). I replaced shaft seal while out. Put pump back on tractor but still has problem. I still think there is an issue/leak on the suction side of the pump since the problem is both the 3 point lift and the steering and since both systems are seperate on the pressure side but share the suction side. Anyone have or seen this issue and have any ideas or answers to what the problem might be??
Thanks, Karl

 

[J_J]

turftech1,

The chattering you hear sounds like pump cavitation, which means the pump is under a strain, and will erode the pump. The foamy oil is caused by air , probably from the suction side of the pump. Do the bubbles go away with time? If the fluid stays foamy, and looks like milk, it may have water in your system. If so, I would drain and replace. and find the source of water input.

What is cavitation?
Cavitation occurs when the volume of fluid demanded by any part of a hydraulic circuit exceeds the volume of fluid being supplied.

This causes the absolute pressure in that part of the circuit to fall below the vapor pressure of the hydraulic fluid. This results in the formation of vapor bubbles within the fluid, which implode when compressed.

Cavitation causes metal erosion, which damages hydraulic components and contaminates the hydraulic fluid. In extreme cases, cavitation can result in major mechanical failure of pumps and motors.

While cavitation commonly occurs at the pump, it can occur just about anywhere within a hydraulic circuit.

In the directional valve described above, the metal erosion in the body of the valve was so severe that the valve was no longer serviceable. The valve had literally been eaten away from the inside, as a result of chronic cavitation - a kind of 'cancer' of the hydraulic system.

In this particular case the cause of the cavitation was faulty anti-cavitation valves, which are designed to prevent this type of damage from occuring.

 

[turftech1]

I guess another helpful thing would be if anyone knows of a way to test or check the transmission pump without having to make the bypass valve tool like JD says you have to? I can't believe you would have to buy or get a by-pass valve cartridge and drill it just to test the flow one time! JD tech manual and diagnostic tests leaves a lot to be desired and doesn't tell you anything about how to check or even find the transmission pump to see if it is bad....

 

[kenstrac]

I would try a gauge to the input of the front pump to see if the feed is fluctuating if not then it might be the pistons or waffle plate in the front pump.the input pump has O rings on the suction side in the castings that the tube fits into did you take the priority valve apart and clean it and check the springs?

 

[turftech1]

This is the open center sysytem and it has a double gear pump driven off the front of the engine so no pistons or waffle plate. I am not sure how I could test the suction side of the pump since all I have are pressure guages for oil and none go negative. I am not sure about how I would connect my flowmeter up since the suction tube from the trans to the pump doesn't have any threaded fittings in series???

 

[kenstrac]

are they using flange fittings at pump and tractor body are the gaskets OK?
can you blow air backwards very low pressure through the high side of the pump and see if you have any leaks at the flange or pump.

 

[turftech1]

They use blocks with o-rings at the pump and just an o-ring on the tubethat goes into the transmission. I replaced both o-rings at the pump but haven't removed the tube going from the trans to the pump to check the trans end. I am trying to see what I can do to figure out where the air is coming from to cause the cavitation. The steering control return is plumbed into the suction going to the pump as well as the relief valve fro the steering so I am thinking maybe about isolating that to see if it may be in the steering section.

 

[Wayne County Hose]

Take the suction strainer out and try it. I have seen problems where the suction strainer appeared to be fine, but when removed from the circuit, all problems went away. It's worth a shot and costs nothing.

 

[turftech1]

UPDATE: I found the problem! Turns out that the high range shift lever broke off and the broken piece and the spring on the lever fell into the transmission and then a piece of metal got sucked up in the transmission pump and disintegrated the large gear! This tractor gets used to blow fairway mowing clippings off 2 days a week for about 7 hrs straight so it is constantly shifting from forward to reverse and the fact that it has over 10,000 hours on it probably contributed to this issue. Yes I said over 10,000 hours! This has been a good tractor but it may be time to put out to pasture Thanks for all the replies and ideas.