Case 480F LL PTO weak when running for 30+ mins

We have a Case 480F LL (has a 3 point and a hydraulic driven PTO instead of a backhoe), we have a small farm and use it for moving dirt, stacking hay bales and running the round baler.

After running the round baler (a Ford 552 that we have run with a 38HP Kubota, the Kubota was marginal on HP, but it ran it) for 20-30 minutes, it starts slowing down when under load, the PTO tach says 300-400RPM rather than 540-600 with the engine running wide open and it will stall if you push too much hay through it and I can hear the pressure relief bypassing (but I have only noticed it bypassing loudly when its stalled, if its bypassing otherwise when hot, it doesn't make enough noise to hear it over everything else).

When this happens, the hard lines going to/from the valve block are hot enough that they are uncomfortable to touch, but not to the point where it hurts or burns you.

Not sure what pressures are, I haven't had a chance to tee in a pressure gauge yet.

Is this behavior to be expected from a hydraulic PTO, or is something likely wrong with it?

Other than this, its a great machine, always starts right up, plenty of power, pushes/pulls hard (even when its hot and the PTO is weak it loads down the engine if you accidentally put it into gear with the parking brake on ), stacks 4x5 round hay bales with a spear chained to the bucket like they aren't even there.

Thanks

Aaron Z

What is your PTO relief valve pressure with no load and at full load? You may need to have a flowmeter test done on supply pump and PTO motor.

I do not know what those pressures are, I don't see a good way to tee into the supply line feeding the PTO motor as it is hard line from the valve to the motor, is there a test port on the motor which I could use to check pressure when running?

I have also been looking for a shop manual but haven't found much other than the usual questionable scanned "reproductions" and haven't wanted to pony up what Case will probably wand for one directly from them.

Aaron Z

The pressure test port for the main hyd. is up at the loader control valve. There is a cap on a hard line going into valve you can tee in there. There's one thing you can check, the line going from the control valve to the PTO motor should be like for the backhoe and may have a power beyond valve, the o-ring could be bad not letting system pressure to rear PTO.
Someone else is probably smarter on these that I am maybe someone will chime in. These 480F LL's are kind of rare.

Coy Lancaster said:

The pressure test port for the main hyd. is up at the loader control valve. There is a cap on a hard line going into valve you can tee in there. There's one thing you can check, the line going from the control valve to the PTO motor should be like for the backhoe and may have a power beyond valve, the o-ring could be bad not letting system pressure to rear PTO.
Someone else is probably smarter on these that I am maybe someone will chime in. These 480F LL's are kind of rare.

Click to expand...

Thanks, I will crawl under there and take a look. I have a pressure gauge teed in on our Kubota and its nice to keep an eye on where pressures are at when using it.
Looks like it should be part #43, correct??

Should need a #12 JIC to my hose and gauge, correct?
https://www.mycnhistore.com/us/en/c...valve/cn/BBEE0978-8FBF-E111-9FCE-005056875BD6

Aaron Z

I was wrong about how PTO plumbs it all goes through the 3-point hitch valve, except for one sensing valve (item 33 attached to line 30) that connects to loader control valve. Here is a diagram for PTO plumbing.

Thanks, will have to look at it closer in person, print the pages out or find a flow diagram to see which lines are the gazinta and which ones are the gazouta.

Aaron Z

Took a look after work, looks like hose 25 is the high pressure inlet (that hose flexes and gets stiff when I deadhead a valve), I should be able to put a JIC run tee between hose 25 and elbow 23 (circled in red in the picture below of my machine) and mount a gauge on that with a JIC to NPT adapter or two.


The two valves with black hoses are the tilt cylinder for the 3 point and the aux valve.
I have them feeding 2 sets of quick connects so I can run the baler hydraulic cylinders off of them.
Will probbaly also see about putting one on the loader valve just to have it.

Aaron Z