4720 PTO issue??? Help!!!

[bill boyce]

I'll check it tomorrow and keep you posted. Thanks for the help.

 

[bill boyce]

I did all checks and it is the PTO valve that is not working properly. Has anyone tackled one before? Any hints or suggestions?

 

[Silvic]

So I understand that you did the test that Spanner recommended and it was fine.

I presume since you stated that the PTO valve was not working properly that you did the test I recommended back in an earlier post.

Specifically the test that is on page 624 of the manual and that both of those tests or at least one of them failed.

Which one failed: Test port plug (A) or Test port plug (B). What were the readings on the gauge on both of the two tests?

 

[bill boyce]

I tested the solenoid and wiring. It gets power when PTO won't engage. When I take off solenoid and put it back on the pto will engage for about ten mins. I did this about 4 times with same results. PTO will engage after taking off solenoid and replacing it. I have not done the valve test. Guess I'll look that up next.

 

[Silvic]

Update: I talked with previous owner and he suggested that I replace hydraulic fluid and filter. I thought he did this before I bought it in Dec. So I just replaced fluid and filter. I cleaned both transmission screens neither were dirty. Fluid was dark almost black in color. Put new filter and fluid in.

Fluid that is almost black in color tells you a lot. None of it good.
When I have swapped my 4720 fluid at the JD recommended intervals I have trouble seeing much of any color differences between the new and the old fluid.
I would say your fluid was "burnt" not just dirty.

JD Hygard as was recommended, is not the JD recommended fluid for your model/year.

It is JD Low Viscosity Hygard. One is JDM-20C the other is JDM-20D.
Why JD felt it necessary to use a different fluid I don't know but I match specs on my equipment unless there is a VERY good reason not to do so.

 

[bill boyce]

I agree with the burnt fluid. I used the J20C.

 

[bill boyce]

I wish I had a good update. I decided to tackle the PTO valve. I replaced all components, orings, springs, shims, etc. When taking it apart all the hyd. fluid just in the pto valve was very grey, like it was full of metal, makes since because the PTO solenoid draws metal particles towards it. But why is there metal in fluid? Other than the grey tint of the fluid everything was in good shape, no dirt or grim. I put it back together and it still does the same **** thing. I mowed a little longer than normal but when I stopped PTO and then re-engage it, it won't turn on. I let it sit for about 20 mins and it worked again, this was the fastest its ever worked after letting it sit. Usually a couple of hours before pto will engage.
The only two things I can think of is: 1. maybe the fluid was run too low for a long time and parts weren't lubed thus metal components wearing. 2. something is going out, bearings or maybe hydraulic pump. When I check the fluid level it is still very clean.
Any more thoughts?

 

[texasranger556]

Did you end up doing the pressure test that was suggested? It would really help you narrow down where the problem is.

 

[Silvic]

Have not seen any update recently. How are you doing with your issue with the PTO?