blew out 4020 hyd pump.

   / blew out 4020 hyd pump. #1  
C

captplaid

Bronze Member
Joined
Dec 12, 2010
Messages
60
Tractor
John DeereX748
Really ruined my day.
Plent of oil
No leaks
Not too many hrs on filter less than 50

Less than 500feet from home and it went out at the intersection. I had just stopped.

Tore out the coupler and put a hole in the radiator.

I always thought most pumps go out from poor maintenance but i didnt see this coming. No signs at all to directly link to the pump.

This tractor has had hyd issues for a while though but i thought we had them taken care of.

Our hyd pressure time with the clutch pushed in was excellent.
 
   / blew out 4020 hyd pump. #2  
Did pump come apart or drive coupler?
 
   / blew out 4020 hyd pump.
  • Thread Starter
#3  
pump seized. Couple came apart.

Yeah, it had oil in it. Fairly fresh and low hours. Changed the oil in the fall of '08 and probably didn't put 100 hours on it.
 
   / blew out 4020 hyd pump. #4  
Don't know if this was possible. We had a 2020 that used to eat hydraulic couplers. Found out the problem was that the entire front end was loose at the 6 bolts that attached the front cradle to the engine. Saw the movement in the radiator cap one day and solved the problem. Not sure, Maybe? These JD pumps are pretty much bullet proof, but how many hours on tractor? Possible maybe one of the pistons in the pump fell out and locked things up? Presure built tooooo high and locked up? There really is not a whole lot inside those pumps to go wrong. Pull it apart and see what you find, likely to be a simple solution, but expensive from the collateral damage.
 
   / blew out 4020 hyd pump. #5  
The hyd pump has 2 tapered roller brgs that one or both could have failed.
 
   / blew out 4020 hyd pump.
  • Thread Starter
#6  
Could the valve in the differential lock be bad and pump oil faster than it's returned to the front pump and starve the pump?
 
   / blew out 4020 hyd pump. #7  
captplaid said:
Could the valve in the differential lock be bad and pump oil faster than it's returned to the front pump and starve the pump?
Click to expand...


Not likely, you mentioned in your first post that the hydraulic pressure time with the clutch pushed in was excellent.

What kind of shape is the pump in, can you rebuild it? IIRC it has a Sundstrand 8 piston pump, I would tear it down and fix it and replace the coupler.
 
   / blew out 4020 hyd pump.
  • Thread Starter
#8  
Tx Jim said:
The hyd pump has 2 tapered roller brgs that one or both could have failed.
Click to expand...

My friend got bored or restless yrsterday while i was at work. He dropped the pump. Found a 3/8 long 1/8 diameter roller or needle valve.

He said the bearings were intact.

Once they got the pump out, it would turn. Perhaps that needle or roller floated up there and locked it up. Moving it around freed it up.

If thats the case, it got through the rear filter.
 
   / blew out 4020 hyd pump. #9  
captplaid said:
My friend got bored or restless yrsterday while i was at work. He dropped the pump. Found a 3/8 long 1/8 diameter roller or needle valve. If thats the case, it got through the rear filter.
Click to expand...

Can you post a photo of the piece found?
 
   / blew out 4020 hyd pump. #10  
There is also a filter screen about the size of a small shotgun shell on the pump's inlet line too.

Where was the needle lodged? Might have been an internal part of the pump.
 
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