PTO problems...

[STx]

This morning I was on a mowing job and my PTO started slowing down. The engine was not bogging down and the slip clutch wasn't slipping, the PTO drive was actually losing power. I could just stop where I was and it would pick back up. At the same time this was going on, I was having something come out of the hydraulic fluid reservoir that looked like steam. I don't think it was smoke because it didn't linger like smoke does, it dissipated like steam would. It happened a couple of times and then everything worked fine for 2.5 hours of mowing.

What could cause this? I've never seen anything like it.

 

[davesl708]

The steam could be from water condensation in the fluid. This would also contribute to the fluid getting to hot.
When was the last time the fluid was changed? Does the transmission and hydraulics share the same fluid?

 

[STx]

I had some hydraulic issues not long ago due to damaging some stuff. I replaced it all but still have aeration in the lines somewhere, I think it's from turbulence though, I don't have any leaks. Fluid was changed about 200 hours ago fully but with the issues I had, I've added 5 gallons to replace what I lost to leaks.

Transmission and hydraulics do share fluid, transmission is running fine.

I dropped it off at the shop this afternoon but I'm just curious as to what might cause it before I hear from them to see if it matches up.

 

[davesl708]

What was damaged? Did it involve the PTO?

 

[STx]

No, it was just a hydraulic line running from the reservoir to the pump and a T fitting.

 

[Mace Canute]

Maybe something here could be of some help.

http://www.tractorbynet.com/forums/new-holland-owning-operating/38974-pto-tc40.html

 

[STx]

Thanks, looks like I have a hydraulic clutch for the PTO so odds are that all these problems are related to the hydraulics issues I've been having.

 

[MrGiggles]

What machine?

If the PTO clutch is actuated by hydraulic pressure, the piston seal could be leaking down and allowing them to slip. Wet clutches that are slipping generate a lot of heat and will burn up the fluid, and release clutch particles. Could also be a valve or pump issue.

 

[STx]

New Holland TC40 DA. I'm pretty sure it's a hydraulic clutch.

 

[MrGiggles]

Does it have a button for the pto or do you have to put it in gear and release the clutch?

Air in the fluid could cause slipping too, how do the rest of the hydraulics behave?

 

[STx]

There's a lever but no clutch, it's a hydro transmission. You drop the engine down to idle, engage PTO and then throttle back up.

Transmission is fine, FEL and 3 point lift have issues because of the aeration, they're dead after it's been sitting for a while, have no movement at idle and very jerky for a while. If you runt he tractor for a few hours, they smooth out but once it sits the problems return.

 

[MrGiggles]

There's a lever but no clutch, it's a hydro transmission. You drop the engine down to idle, engage PTO and then throttle back up.

Transmission is fine, FEL and 3 point lift have issues because of the aeration, they're dead after it's been sitting for a while, have no movement at idle and very jerky for a while. If you runt he tractor for a few hours, they smooth out but once it sits the problems return.

I think you've already found the problem, you need to find out where the pump is sucking air.

 

[STx]

The service guys called today, they think the pump is bad and it's causing capitation. They said that it's running much hotter than it should be. I had noticed it seemed to be pretty warm but hadn't ever checked the temp before the problems so wasn't sure if it was hotter than normal.

If I get a seal kit and rebuild the pump, should that be enough to fix it if the pump is the problem? Or will a new/reman pump be required?

When I messed up the fittings, they were on the supply side line for the pump so it's possible that it could have run completely dry, or close to it, at some point.

 

[MrGiggles]

Cavitation is normally caused by a restriction in the suction line, I'd think that a worn pump would be less likely to cavitate, but I'm not a hydraulics expert.

Are you 100% sure you're not sucking air at one of the suction lines?

Running a pump dry does shorten its lifespan, but I've not seen one die from running dry one time.

 

[STx]

Yeah, I kind of thought cavitation in the pump sounded unlikely. The only other place there could be a restriction is in the supply line from the T that was damaged to the pump. The T that was damaged is where it splits off to the hydro trans pump and the other hydraulics pump. The trans is working fine so I think I need to pull that line off and check it for problems. It's possible that a stick or something got jammed in there or that the O-Ring where it connects to the pump is damaged. I think I'm going to start there before replacing anything more expensive and if I don't find an issue there I guess I'll see how hard it is to break the pump down and see if anything in it looks broken or clogged.

 

[ak9]

sounds to me like there is air somehow entering in b4 the "other" hyd. pump . Does The hydraulic fluid show any signs of emulsifing/ clouding etc.?