PT-180 Clicking or thunking from wheels under stress

[James23]

So my PT-180 has been flawless..up until last weekend. I went to push some brush back up into a pile, and instead of powering up the hill, my PT-180 just started thunking or clicking once the wheels encountered any resistance. The thunking noise has been happening for a while now, but only decelrating while going down steep hills (or going full speed and letting up on the pedal quickly). I assumed it was a pressure bypass or something normal...guess not.

Bucket works fine, no power issues.

I shot a quick video to show the issue: iCloud

Tractor has about ~75 hours. Purchased in 2019. Maintained pretty well.

I called Terry up this morning here and he indicated that the "valve plate" on my tram pump was probably having issues. So it appears that I am now going to be pulling the tram pump.

Anyone else experience this issue?

Could I have done anything to cause this?

How hard is the tram pump to pull out? Any instructions / recommendations on how to pull it out?

I'm a reasonable shade-tree mechanic, but this PT is my first experience with hydraulic systems.

 

[m5040]

My PT180 does it going down steep hills, it has over 100 hours (maybe 150, can't remember).
When cutting grass and going down grade, it clunks and picks up some speed. Hasn't done it under any other conditions yet. If you talk to Terry again, feel free to mention it.

When you tackle the job, wash it to get all dust dirt out. Take pictures. Label the hoses (mine has number written on each fitting from factory). I don't think it would be too bad to get at it. You may be able to just unbolt the hydraulic pumps without removing hoses and swing back far enough to get tram pump out.

Please let us know how you are making out.

I don't think you could have caused it. They seem to be built very well. When I remove snow, it is always going back in forth rapidly with tires spinning and no issues that I notice. I thought it might be a defective wheel motor causing an "open circuit" in that hydraulic flow.

With that said, I would take Terry's advise over mine. But if it is easy to isolate the wheel motors one by one and see if the others get traction it may be worth the effort. Can you use a stethoscope (or a long screw driver held to your ear) and hear bypassing oil in one motor more then the others? If you can hear a difference you may want to take (one) of the large hoses off a wheel motor, plug (the hose and fitting on motor) and try to move machine. If that motor is defective and blocked off, the others will then get pressure and move.

I say that even know there are 2 wheel motor circuits. But in real life, when stuck all mine just spin one wheel until I give it a tremendous amount of tram then the others start to kick in and that one wheel that was initially driving spins at what looks like highway speed.

Look for metal in the oil (like metallic paint).

I am in CT if your close.

 

[MossRoad]

Only thunking I've ever heard on my 2001 PT425 is when the parking brake partially engages. I don't think that's your issue, though, as you said you can recreate it.

 

[oldnslo]

Is there a drive pump for different wheels or one common drive for all?Does the machine stop moving under load while clunking? Are all of the pumps on a common drive shaft or in other words piggy backed together? I.e. tram / travel drive and implements?

Not familiar with PT units so may be silly questions on my part.

Just wondering if something on drive coupling could be failing since should be nothing hydraulic to clunk on hydrostatic drive.

 

[James23]

Clunk is perhaps not the correct word. IF you watch the video I posted, it shows the problem. I would call it akin to a slipping transmission.

Yes the machine fully stops moving when it encounters driving resistance (going up a hill, pushing things, etc). It also lost a few mph on top speed. Happens in forward and reverse.

The thunking (or whatever weird noise) also will come from the rear wheels when i put stress on them and go in reverse (ie clomp bucket into ground, go in reverse). All wheels are acting the same ,which makes me think not a wheel motor.

I believe my pt-180 has 1 pump for drive, 1 pump for the rest. The drive pump (aka tram pump?) is connected directly to the engine.

Either way, the tram pump is coming out.

@m5040 Thank you for the information. I wish I was closer to CT, but unfortunately I am over in the midwest (Minnesota).

Anyone know a mechanic in MN who would want to Remove and Reinstall the pump for me? (I can do it myself...I think, but I would love to hand 'er off to a more professional person and just have 1 less thing to worry about).

 

[MossRoad]

Is there a drive pump for different wheels or one common drive for all?Does the machine stop moving under load while clunking? Are all of the pumps on a common drive shaft or in other words piggy backed together? I.e. tram / travel drive and implements?

Not familiar with PT units so may be silly questions on my part.

Just wondering if something on drive coupling could be failing since should be nothing hydraulic to clunk on hydrostatic drive.

There's one variable volume hydraulic pump that drives 4 hydraulic wheel motors in a series/parallel arrangement. No driveshafts.

 

[MossRoad]

Clunk is perhaps not the correct word. IF you watch the video I posted, it shows the problem. I would call it akin to a slipping transmission.

Yes the machine fully stops moving when it encounters driving resistance (going up a hill, pushing things, etc). It also lost a few mph on top speed. Happens in forward and reverse.

The thunking (or whatever weird noise) also will come from the rear wheels when i put stress on them and go in reverse (ie clomp bucket into ground, go in reverse). All wheels are acting the same ,which makes me think not a wheel motor.

I believe my pt-180 has 1 pump for drive, 1 pump for the rest. The drive pump (aka tram pump?) is connected directly to the engine.

Either way, the tram pump is coming out.

@m5040 Thank you for the information. I wish I was closer to CT, but unfortunately I am over in the midwest (Minnesota).

Anyone know a mechanic in MN who would want to Remove and Reinstall the pump for me? (I can do it myself...I think, but I would love to hand 'er off to a more professional person and just have 1 less thing to worry about).

Can't open the video.

 

[James23]

Lets try youtube, here is a quick video with the issue at the end:

 

[MossRoad]

Ooooo. That's not good.

Does it in forward and reverse?

I'd trust Terry's opinion over mine, however, with any luck, it might just be the lovejoy connector set screw(s) between the pump and the motor or rubber star between the lovejoy sections slipping when under pressure. You'll have to get to them when you pull the pump, so inspect as you proceed.

 

[James23]

Both forward and reverse. In reverse, the back wheels start doing it.

 

[oldnslo]

Ooooo. That's not good.

Does it in forward and reverse?

I'd trust Terry's opinion over mine, however, with any luck, it might just be the lovejoy connector set screw(s) between the pump and the motor or rubber star between the lovejoy sections slipping when under pressure. You'll have to get to them when you pull the pump, so inspect as you proceed.

If there is a lovejoy coupling between engine and pump that would be my first thought on point of failure.

Does that same lovejoy also run the implement pump?

 

[ponytug]

I'm with @MossRoad on both counts; I trust Terry over me any day of the week and twice on Sunday, but I will hope that the stuttering might be a bad LoveJoy connector.

FWIW: I had to replace a wheel motor at 5 hours, but the tractor has been a workhorse for the last fifteen years.

All the best,

Peter

 

[m5040]

Ooooo. That's not good.

Does it in forward and reverse?

I'd trust Terry's opinion over mine, however, with any luck, it might just be the lovejoy connector set screw(s) between the pump and the motor or rubber star between the lovejoy sections slipping when under pressure. You'll have to get to them when you pull the pump, so inspect as you proceed.

I would think if it was the Lovejoy slipping, it would also slip when he deadheads a hydraulic cylinder since all the pumps drive through each other.

But one way to test that theory would be to see if the loader will raise when the drive is ratcheting. If the coupler was slipping due to operator calling for drive torque then the hyd pump would also stop turning in unison.

 

[MossRoad]

I would think if it was the Lovejoy slipping, it would also slip when he deadheads a hydraulic cylinder since all the pumps drive through each other.

But one way to test that theory would be to see if the loader will raise when the drive is ratcheting. If the coupler was slipping due to operator calling for drive torque then the hyd pump would also stop turning in unison.

Yes, I forgot about that. My 2001 model PT425 is set up differently. The tram pump is ahead of the engine and the main PTO/steering-FEL-aux PTO pumps are behind the engine.

 

[cqaigy2]

Man that sounds and looks really unusual. Sounds like there isn't a smooth flow of oil when you are putting strain on the pump. i wonder too, if the tram pump is having issues.

I don't recall, isn't the filter in the tram pump circuit? Possibly the filter is partially plugged.

 

[ponytug]

Man that sounds and looks really unusual. Sounds like there isn't a smooth flow of oil when you are putting strain on the pump. i wonder too, if the tram pump is having issues.

I don't recall, isn't the filter in the tram pump circuit? Possibly the filter is partially plugged.

Yes, the suction filter provides the make up oil to the variable volume pump. So, yes, if there were a filter issue, it might cause bad cavitation, and the knocking like sounds.

It does sound mechanical to me though, which doesn't rule out the pump having issues, which is Terry's point.

All the best,

Peter

 

[MossRoad]

The filter supplies oil to the charge pump inside of the variable volume pump. Nothing is filtered going to the PTO/aux PTO pumps that I know of.

 

[MossRoad]

This is going to be one of those examples we're going to refer to in years to come. The video is excellent troubleshooting material that we can refer to in the future.

 

[James23]

Yes, the suction filter provides the make up oil to the variable volume pump. So, yes, if there were a filter issue, it might cause bad cavitation, and the knocking like sounds.

It does sound mechanical to me though, which doesn't rule out the pump having issues, which is Terry's point.

All the best,

Peter

So forgive my ignorance here, I'm not an expert in hydraulics. The other hydraulic systems all seem to work fine and have full power, so I don't think it could be a filter / cavitation issue?

Either way, I will be attempting to tear it apart this weekend, hopefully that goes well....

 

[airbiscuit]

I don't know anything about Power Tracs other than what MossRoad tells me, but I'm wondering if there is a pressure relief valve that is bypassing and resetting ...