4720 PTO issue??? Help!!!

[bill boyce]

I recently bought a 2008 4720 cab with 900 hours. I am having a recurring problem with the pto. It came with a mid mount mower. Every time I mow with either the mid mount 6' mower or my 7' brush hog, after about 20 mins of mowing and I disengage the mower (pushing the yellow switch), the pto will not turn on again. The lights on the dash will light up either with the 540 or 2000(mid mount) but neither pto will not engage. Once the hydraulic fluid cools down(usually overnight) the pto will work fine until I turn off pto then I have to let it sit for a long time then it works again. I replaced the pto switch even though it wasn't bad and I just replaced the pto solenoid and armature. I have looked all online and talked to the head shop manager at my local dealer and a couple of other dealer mechanics, they haven't heard of this happening and they don't know what it could be. I am so frustrated with this. I can't afford to take it to the dealer. Any help or ideas would be great, if anyone has heard of this on other tractors please let me know. :banghead:

 

[joecdeere]

I have a PDF of the technical manual you're welcome to. Shoot me your email if wanted

Joe

 

[Silvic]

Never heard of this.
Since you state that the failure condition changes as the fluid cools down, it sounds as if it might be hydraulic fluid related from your description.
When was the last time the fluid was replaced, the filters changed, etc?
There is if I remember correctly one inline filter (two if you have power beyond) and the one big main filter.
When it happens have you checked the hydraulic fluid level. If contaminated you could have foaming.
What is the condition of the fluid, hopeful not milky?
Have you ever had the pto shut off after an extended use like an hour or two of use or does this only happen after disengagement and the reengage attempt?
With it being a 4720 it is e-hydro. How is the steering and drive-ability after it happens any jerkiness or slipping in any high low medium position.

 

[bill boyce]

When I bought tractor I was told all filters had just been replaced. I may do that next and see (just taking the word of the owner). Yes manual calls for cleaning the suction tube, inline filter and replacing the large filter.
Fluid is clean, the first time the pto stopped working I checked fluid level and it was low, I added fluid but still didn't engage pto. Yes I have had pto shut off after about 1.5 hour of use that is the longest I have been able to mow at one time. Yes it is e-hydro, everything else on tractor works great and has plenty of power. It has a loader and it works great too.

 

[bill boyce]

I sent it in a PM.

 

[Silvic]

Just went to the manual and looked up some stuff.

Do you have a service manual?

Page 621 states under trouble shooting:
Problem
3. PTO does not operate ..................................... a. PTO valve faulty

Have you done a test on the valve? Page 624 PTO valve pressure test

If you don't have a manual PM me your email and I can send the applicable pages. The whole document is way to big but it will show you how to do the test.

Oh I see you have another offer for the manual It is large. 127 MB

 

[bill boyce]

I have not done a valve test. I'll pm you.

 

[bill boyce]

I just looked up pick of valve. I replaced the solenoid and armature on the valve. Yes please send me info on how to do valve test. I just mowed with tractor using the belly mower mowed great for about 30 min, turned it off to back up, would not work again. Guess I'll finish mowing in the morning.

 

[joecdeere]

Bill, manual download link should be in your email

 

[waycoolmarine]

the ptos engage with electric coils ,my guess would be theres metal floating around in oil and attaches to magnets , when you turn off the are still holding metal and will not grab pto try checking the screen in hydro oil , if you have a bunch of shavings don't freak out it will be ok , ive seen more than a couple tractors with lots of shavings , that's why theres a screen