L2502 hydraulic noise

[Russell King]

For a position. I can go fall down, but I don’t know how to lock it or or if there is one.

On some tractors there is a bolt and a wingnut that can be used to set where the three point lever goes down to. It was used to set the depth of a plow, set a mower to the same height…

It can be moved above the three point control lever to lock it in the down position or limit the up travel.

 

[TheOldHokie]

how is this any different with a 3 point implement on and in the full raised position? Thanks

You will have the same deadheading problem.

But when the hoe is attached you are also back pressuring the BH control valve which can and does damage seals = big $$$$. I thought the backhoes all came with a lockdown latch for the position contrkl lever. Apparently not.

 

[TheOldHokie]

even with the backhoe fully removed and using a 3 point implement it still makes the noise

Yes - the feedback linkage is out of adnustment You need to fix it.

You are stressing the backhoe vslve and the tractor hydraulic system big time with this behavior.

 

[Russell King]

deleted same information as above (typed too slow)

 

[Lrex]

I hear what you are saying. i am failing to see the difference between the backhoe on or off and the relation to the position control lever. I understand if the position control lever is in the raise position it is apply pressure to that system regardless if an implement is attached to it. If the backhoe is on and not in use it is bypassing full flow back to tank Not via a pressure relief. if the backhoe is off, the supply/pressure line is connected back to the return to tank line.

currently ALL implement, backhoe, third function, loader and 3 point operate completely normally.

I’ll see if I can dig up a hydraulic diagram

 

[Russell King]

Read post #22 again.

But in more detail…

Backhoe off there is no backhoe valve to damage. So if the three point lever goes to full up and the feedback linkage is maladjusted then the hydraulic pressure builds up between the tractor hydraulic pump and the relief valve until it reaches the relief valve set point. Then the pressure is basically static at that high pressure until something is changed. This pressure is in the hoses that would be connected to the backhoe if it were attached. The other valves are protected by their Power Beyond sleeve installed in each valve.

Now same situation but the backhoe is installed. The backhoe valve does NOT have a PB sleeve installed. So all the pressure that is built up between the relief valve and the pump is being applied to seals in the backhoe that are not rated for that pressure. That will damage the backhoe valve.

The three point hitch is not supposed to be utilized when the backhoe is installed. The backhoe installation basically renders the three point system inoperable so the lever should be in the down position at all times so that it does not go into relief and damage the backhoe valve.

 

[TheOldHokie]

I hear what you are saying. i am failing to see the difference between the backhoe on or off and the relation to the position control lever. I understand if the position control lever is in the raise position it is apply pressure to that system regardless if an implement is attached to it. If the backhoe is on and not in use it is bypassing full flow back to tank Not via a pressure relief. if the backhoe is off, the supply/pressure line is connected back to the return to tank line.

currently ALL implement, backhoe, third function, loader and 3 point operate completely normally.

I’ll see if I can dig up a hydraulic diagram

I dont need a diagram - i know it inside out.

The position control feedback linkage is out of adjustment. When the lever is full up the feedback system continully cycles the position control valve open and closed trying to raise the lift past its mechanical limit. When the valve opens it deadheads the pump which unloads via the relief. When the lever is at a lower position there is no problem. Pure and simple.

When the backhoe is connected that deadhead condition is back pressuring the BH control valve. Its not designed to handle that sort of pressure and the seals in the valve can be damaged. Replacing those seals can be a big $$$ repair bill.

Bottom line - you need to correct the feedback lingage adjustment AND make sure the 3pt kever is kept FULL DOWN when the hoe is connected.

 

[Lrex]

I dont need a diagram - i know it inside out.

The position control feedback linkage is out of adjustment. When the lever is full up the feedback system continully cycles the position control valve open and closed trying to raise the lift past its mechanical limit. When the valve opens it deadheads the pump which unloads via the relief. When the lever is at a lower position there is no problem. Pure and simple.

When the backhoe is connected that deadhead condition is back pressuring the BH control valve. Its not designed to handle that sort of pressure and the seals in the valve can be damaged. Replacing those seals can be a big $$$ repair bill.

Bottom line - you need to correct the feedback lingage adjustment AND make sure the 3pt kever is kept FULL DOWN when the hoe is connected.

I appreciate all the responses. I’ll insure the lever is down when not in use. i don’t doubt repairs are costly.

What is leading you to believe that the feedback linkage is out of adjustment? With the 3 PT lever in the fully down or any position, it still makes the noise. Also, the BH77 rated pressure is 2477psi and the pressure relief for the pump is set to 2200-2390psi. even if it was reliving pressure it is still under the max for the BH. The main pump relief valve opening and relieving pressure is not the same sound in the video.

 

[TheOldHokie]

I appreciate all the responses. I’ll insure the lever is down when not in use. i don’t doubt repairs are costly.

What is leading you to believe that the feedback linkage is out of adjustment? With the 3 PT lever in the fully down or any position, it still makes the noise. Also, the BH77 rated pressure is 2477psi and the pressure relief for the pump is set to 2200-2390psi. even if it was reliving pressure it is still under the max for the BH. The main pump relief valve opening and relieving pressure is not the same sound in the video.

The backhoe valve is rated for "2477" INLET pressure. The tank OUTLET port is rated for a fraction of that - probably closer to 500 PSI max. Damaged tank seals caused by deadheading the backhoe valve into the 3pt valve or a bad return line coupler is a well known and documented failure. That is not debatable.

The repeated surging with the 3pt lever full up and no operator action is consistent with a feedback linkage problem.

Now you are telling me the problem exits even when the 3pt lever is full down. That is new informatjon. Are you 100% sure of that?

Dan

 

[Lrex]

The backhoe valve is rated for "2477" INLET pressure. The tank OUTLET port is rated for a fraction of that - probably closer to 500 PSI max. Damaged tank seals caused by deadheading the backhoe valve into the 3pt valve or a bad return line coupler is a well known and documented failure. That is not debatable.

The repeated surging with the 3pt lever full up and no operator action is consistent with a feedback linkage problem.

Now you are telling me the problem exits even when the 3pt lever is full down. That is new informatjon. Are you 100% sure of that?

Dan

Yes I am sure.

if you can’t tell in the video the noise goes away the moment the rpm’s come off idle.

Also, when the noise is happening I can let’s say raise the loader to max height so the relief kicks in and you clearly hear the relief and the noise separately As two completely different noises. just trying to add more to the picture…….

 

[TheOldHokie]

Yes I am sure.

if you can’t tell in the video the noise goes away the moment the rpm’s come off idle.

Also, when the noise is happening I can let’s say raise the loader to max height so the relief kicks in and you clearly hear the relief and the noise separately As two completely different noises. just trying to add more to the picture…….

This certainly casts dkubt on the 3pt theory.

Lets revisit the video. It appears to me the engine loads up when the noise is heard. Is that your observation?

 

[Lrex]

This certainly casts dkubt on the 3pt theory.

Lets revisit the video. It appears to me the engine loads up when the noise is heard. Is that your observation?

I don’t hear loading or see and change in RPM.

 

[TheOldHokie]

I don’t hear loading or see and change in RPM.

OK - apparently thats you goosing the throttle.

Looks like I also jumped the gun on the knowing the hydraulic circuit. The L2502 has a hydraulic PTO and a "regulator valve" which is different than the L2501. I dont know what that regulator valve does but it could easily be the source of the noise. I am going to see if I can find a L2502 WSM.

My apologies - it looks like my initial diagnosis is way off base

Dan