3520 rockshaft problem

   / 3520 rockshaft problem #1  
debushau

debushau

Bronze Member
Joined
May 31, 2007
Messages
89
Location
PA/NJ
Tractor
JD4720, ASV Scout, XUV 550
I have a 3520 and just installed the power beyond kit this weekend. I installed it by the book and it was a fairly straightforward install. The kit was missing the spring for holding the toplink and seemed to have an extra bulkhead reducer fitting that did not go anywhere.

Anyway, the issue that cropped up after the install is with the rockshaft. The 3 point hitch goes up and down fine but when I set it to a specific height it will pulse up and down slightly. By that, I mean the arms go down slightly (1/8 of an inch) and back up again. This happens every 3 to 4 seconds and I can feel the a pulse move through the piping at the back. When it's fully down, the pulsing stops.

I checked the fluid level and topped it up. I doubt it's air as the system bleeds air very quickly. My only idea is maybe the (new) filter is blocked (I was careful to install it the right way round as the manual warns). Any ideas on what could be wrong?

thanks
 
   / 3520 rockshaft problem
  • Thread Starter
#2  
Reading through some old postings, it looks like the issue might be dirt in the bypass valve.

Is the bypass valve the valve on ball bearings which is on the end of a large hex/acorn nut that screws into the housing under the seat - just above where the rockshaft pipe goes into the block/rear end housing on the starboard side. Sounds like it's time to buy a workshop manual.
 
   / 3520 rockshaft problem #3  
debushau said:
Reading through some old postings, it looks like the issue might be dirt in the bypass valve.

Is the bypass valve the valve on ball bearings which is on the end of a large hex/acorn nut that screws into the housing under the seat - just above where the rockshaft pipe goes into the block/rear end housing on the starboard side. Sounds like it's time to buy a workshop manual.
Click to expand...

Yep, sure sounds like something is wrong with the valve. they are replacing mine this week and it came from the factory like that.
 
   / 3520 rockshaft problem #4  
Nuru said:
Yep, sure sounds like something is wrong with the valve. they are replacing mine this week and it came from the factory like that.
Click to expand...

Ditto. My 5425 came from the factory with approximately the same rockshaft issue. Dealer replaced the valve, now all is good.
 
   / 3520 rockshaft problem #5  
tjkadar said:
Ditto. My 5425 came from the factory with approximately the same rockshaft issue. Dealer replaced the valve, now all is good.
Click to expand...
Sounds like either defective parts, defective assembly or just a bad day for inspections got us!:eek:
 
Last edited:
   / 3520 rockshaft problem
  • Thread Starter
#6  
I will check and clean the pressure relief valve first. Since it was working fine before I put in the power beyond, I am hoping that some dirt got in the system during assembly.

The PB kit is just a bunch of tubes that only go together one way so I figure if it's not leaking, it's assembled okay. The tractor is still under warranty so I guess I could get the dealer to do it if it's not dirt.
 
   / 3520 rockshaft problem
  • Thread Starter
#7  
I pulled out the pressure relief valve and found the remnants of an o-ring in there. Once removed, the rockshaft is back to normal. It's an entirely separate question as to where the piece of the o-ring came from.
 
   / 3520 rockshaft problem #8  
Wow, glad you got the issue solved.
 
   / 3520 rockshaft problem #9  
I added PB when I got my 448. The dealer installed while they added the hoe. The next time put on the 3pt hitch same issue your having. The dealer ended up replaceing the valve. I've heard of this alot so it seems a common issue.

Matt T.:D
 
   / 3520 rockshaft problem #10  
Apparently this issue has occurs through various models and once fixed, then the issue does not return.
 
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