Independent PTO problems

[dtj1]

Hi. I am new to this forum and I need help. I have a 2008 Massey Ferguson 2625 four wheel drive tractor with independent PTO. When I turn the PTO on, the 3-point lift arms stops working. It has a new Hydraulic filter, and new oil. I am getting 2350 lbs. of pressure at 3-point lift arms test port. As soon as I turn the PTO on, the pressure falls to zero. I pulled the hydraulic lift cover off and I put the cap and stand pipe back on, I started the tractor to check to see if I had any leaks around the o rings, on the pipe but did not see any leaks, I had a good flow of oil came out of the stand pipe that feeds the 3-point lift arms and soon as I turned the PTO on, the oil from the stand pipe stopped and when I turned the PTO off the oil comes back through the stand pipe. Also the priority valve(part #2749A00401) has a open hole with a t stamped on it. I am wondering if a plug or something goes in that open hole. I nor anyone else cannot find any pictures of the priority valve to see if anything is missing. I've talked to several Massey dealerships and a service rep and they all told me they have never heard of this before. Does anyone have any ideas?

 

[Dave M7040]

Does your tractor have a loader, a loader with third function valve, or other hydraulic features like top and tilt.
Have you modified it or added to it or is is as stock as when it left the factory?
Dave M7040

 

[dtj1]

Yes it has a loader, It is stock as when it left the factory, and I have not added anything. Priority valve 2 with green sharpie is pointing to hole, that I am wondering if something is supposed to be in.

Thanks

 

[TractorTech]

Welcome to TBN!
Was it working, then stopped? Does oil come out of that hole in the priority valve?

 

[dtj1]

Welcome to TBN!
Was it working, then stopped? Does oil come out of that hole in the priority valve?

It had been working but I haven't used bush hog for about a month and when I went to use the bushhog this time that is when I had the problem. I do have a very small amount of oil come out of the hole from the priority valve when the PTO is engaged.

 

[rScotty]

Do you have the shop manual? It should show the hydraulic diagram for te 3pt and PTO.
With that, you should be able to identify which components might be diverting the flow. It will certainly show that diverter valve and that will tell you if the plug is missing. Some manuals list typical pressures at test points. If it isn't in the shop manual, ask the dealer.

So far it sounds like a stock system that worked fine for years and suddenly stopped working. Is that true?
If so, then something must have happened to divert the flow. The first thing any mechanci would want to know is what the possibilities are. The possibly missing plug is one; another might be a leaky PTO motor, or a 3pt relief valve that is stuck open.
The hydraulic diagram in the shop manual will show both of those possibilities and more. Most manuals also list the pressures at a test point or two to help diagnosis.

Here is the type of hydraulic diagram I'm talking about. Most dealer shops have these flow diagrams. They save a lot of time. These are from Yanmar showing a PTO with a manually-driven PT, but most of the 3pts are similar even if the PTO drive is not.
luck,
rScotty

 

[dtj1]

Yes it was working and then the next time I went to use it, the problem started and it is a stock system. I do have a shop manual from a Massey Dealer that went out of business, it's not very good on the PTO diagram and trouble shooting, but I drew in the missing parts (See Attachment). The pressures are good but I don't have a flow meter to check the flow. I was told to pull the lift cover off and start the tractor, if I am losing that much pressure, then I should see it, but nothing stood out to me and that's when I seen the hole in the priority valve and was asking about it. I have now drained the hydraulic oil and pulled the filter, to look for a plug or anything in the sump. I haven't found anything yet. I have a camera scope ordered. What the Massey Dealer told me the problem I am having does not make sense, because these are separate systems. The lift arm has its on pump, so does the PTO and the front end loader. The only thing they share is the suction filter. One should not affect the other, so the PTO is robbing all the fluid. So I am thinking I may have to invest in a flow meter. The bad thing is the priority valve and solenoid/flow control valve is non-serviceable and are not cheap, so I am trying to make a calculated guess.

 

[rScotty]

Yes it was working and then the next time I went to use it, the problem started and it is a stock system. I do have a shop manual from a Massey Dealer that went out of business, it's not very good on the PTO diagram and trouble shooting, but I drew in the missing parts (See Attachment). The pressures are good but I don't have a flow meter to check the flow. I was told to pull the lift cover off and start the tractor, if I am losing that much pressure, then I should see it, but nothing stood out to me and that's when I seen the hole in the priority valve and was asking about it. I have now drained the hydraulic oil and pulled the filter, to look for a plug or anything in the sump. I haven't found anything yet. I have a camera scope ordered. What the Massey Dealer told me the problem I am having does not make sense, because these are separate systems. The lift arm has its on pump, so does the PTO and the front end loader. The only thing they share is the suction filter. One should not affect the other, so the PTO is robbing all the fluid. So I am thinking I may have to invest in a flow meter. The bad thing is the priority valve and solenoid/flow control valve is non-serviceable and are not cheap, so I am trying to make a calculated guess.

Well, at least you do have a hydraulic diagram. That system is just enough different from a standard one to make a diagram a real help. Your hand drawn in PTO part make perfect sense, but the fact that they were not there originally makes me wonder if the (Independent)PTO was an option or afterthought. Do you know?

As you have drawn it, what you are calling the "priority valve" - not shown originally - has an input from the IPTO pump and an output to the solenoid flow switch. But I am puzzled why you are calling it a priority valve? A priority valve divides an input flow into two outputs. So if that is a priority valve, it should have an input and at least two outputs. Where is the other output?
Is the other output the missing plug?? And if so, is the missing plug in fact a relief valve? Or the outlet from one? If so is there a relief valve inside that aluminum valve block? In that case, the priority would be IPTO vs RELIEF and that would make sense. One would expect a relief valve somewhere in the IPTO system in case the PTO is stalled. Otherwise a stalled PTO would blow up the pump and maybe break the shaft.

Then we go over to the soleoid flow control (on/off) and I see that you have drawn in two return lines. Why are there two? Any idea?

Flow meters are very expensive but wonderful tools to have. I don't know of a small one for measuring flow in home shops for compact tractors. Even large dealers there days are unlikely to have a flow meter, although diagnosing hydraulics without one is a lot like doing electricals without a VOM.

Don't let me talk you out of a flow meter, but also consider buying or making a hydraulic pressure test kit (Amazon has them), and using that meter to plug the hole in the "priority valve". If so you might want to incorporate a relief valve in that test line just in case. It might show no pressure unless the IPTO is turned on and then stalled, and I would not recommend stalling the IPTO as a test even if you could....because it might cause major damage... Probably would.

rScotty

 

[Dman1981]

Did you clean sump screen just because they look clean is not always true

 

[dtj1]

Did you clean sump screen just because they look clean is not always true

This one does not have a screen, it has a filter and it is a new filter.