Woods BH80X issues

[prollynotjeff]

My father recently purchased a DK40SE with a woods backhoe and I noticed a few things that I haven't noticed with other units

1. The main boom function seems very jerky even with the tractor idled all the way down its extremely touchy.

2. The main boom tends to drift towards the ground, I expect leakdown overnight but not while the tractors running. At the time this happened I was not running the unit but he was sure that the remotes were flowing.

Has anyone had these issues? The setup was at my house for a week and it has no leaks, its a low hour setup and in what appears to be really good condition.

Thanks for the help!

 

[RickB]

A leaking piston seal will leak whether oil is flowing through the valve or not. Repair the boom cylinder and you symptoms will probably disappear.

 

[prollynotjeff]

Rick anyway to confirm its this? thanks for the help!

 

[CADplans]

You need to isolate whether it is the valve or cylinder.
You need to diagnose the system by pushing the rod into the cylinder.

Lift the tractor with the backhoe boom cylinder,,, if the tractor settles back down, it is the valve.
If it does not go down, the issue is the cylinder piston.

 

[RickB]

You need to isolate whether it is the valve or cylinder.
You need to diagnose the system by pushing the rod into the cylinder.

Lift the tractor with the backhoe boom cylinder,,, if the tractor settles back down, it is the valve.
If it does not go down, the issue is the cylinder piston.

That makes absolutely no sense whatsoever, except the part about needing to determine whether it is the valve or cylinder.
The cylinder piston seal is about 90% likely to be the culprit, but not 100%.

 

[CADplans]

That makes absolutely no sense whatsoever, except the part about needing to determine whether it is the valve or cylinder.
The cylinder piston seal is about 90% likely to be the culprit, but not 100%.

This has been discussed many times before,,, maybe not at TBN.
I think it is like religion,,, I did not believe at first. :confused2:
To become a believer, you must be led to the answers,,,:laughing:

If the rod is going into the cylinder,,, the volume in the cylinder is increasing.
If the valve is holding, the cylinder will lock up, there is no where for the oil to go.
Fluid is non compressible.

lifting the backhoe boom, and waiting, if it is the cylinder piston, it can create a vacuum.
volume in the cylinder is decreasing, if the valve is holding.
To some extent, the cylinder can extend,, because a vacuum can form.

A few molecules of air, or other gas can fill a large space,, per the equasion

PV=NRT

I guess you can Google the subject, and find the same discussion other places.

 

[RickB]

Discussion and real world results can vary. The volumetric difference can be compensated for by several feet of hose expanding due to pressure gain, and normal, in specification valve spool leakage under pressure. Spool bores are, after all, metal to metal with clearance sufficient not to bind even under thermal expansion. Oil can also be exhausted via circuit relief valving.

Bottom line, more positive troubleshooting than you suggest is necessary to pinpoint cylinder piston seal failure. A simple, clean, foolproof method is to use a non contact infrared thermometer.

 

[prollynotjeff]

Discussion and real world results can vary. The volumetric difference can be compensated for by several feet of hose expanding due to pressure gain, and normal, in specification valve spool leakage under pressure. Spool bores are, after all, metal to metal with clearance sufficient not to bind even under thermal expansion. Oil can also be exhausted via circuit relief valving.

Bottom line, more positive troubleshooting than you suggest is necessary to pinpoint cylinder piston seal failure. A simple, clean, foolproof method is to use a non contact infrared thermometer.

I assume this cylinder would be warmer than the rest? I have an infrared thermometer I can use but I probably wont be able to try it till Friday.

Thanks for the help guys!:cool2:

 

[RickB]

I assume this cylinder would be warmer than the rest? I have an infrared thermometer I can use but I probably wont be able to try it till Friday.

Thanks for the help guys!:cool2:

Hold the boom in the full up position and cycle the lever between lift and neutral so as to build relief pressure (if it even will) but not for extended periods of time ( use on/off cycles for a few minutes). If the piston seal is leaking, the barrel will show a temp increase exactly where the piston sits, in this instance at the base end of the barrel. a temp increase of as little as 5 degrees proves a leaking piston seal. Best to start with a cold system.