JD 4320 Test drive issues (Brakes, Hyd pump)

[svdsinner]

Just drove a 4320 I really liked, but it had 2 issues I've got questions on:
1) The brakes gave a really weird kickback sensation when I pushed on them. Basically, when I pushed the brake pedal all the way down, the pedal would suddenly push itself back up about an inch. Any ideas what this could be? (Happened on both L & R)
2) The hydraulic pump was making a knocking sound, and the 3pt would move jerkily to the rhythm of the knocking when being raised/lowered. I've seen this before on a 4020, and I can't remember the exact cause, but I think it was a cheap repair to the bottom of the hydraulic pump. Anyone know the specifics on this and what it takes to repair?

 

[jenkinsph]

Two things I would check on the hydraulics, the inline filter on the pump lower side in the suction line and the transfer charge pump in the rear base. From your description it sounds like a restriction or low flow issue on the inlet side of the hydraulic pump.

Before buying I would also perform a pressure test of the hydraulic system IIRC should be about 2200 psi.

About the kickback on the brakes, I had a 3020 diesel that did this but the brakes worked for years without issue.

 

[Uncle Wayne]

I've noticed the brakes on my 4320 do the same thing but work as expected and hasn't been a problem for over 2 years now.

All I can say about the Hydraulic problem is mine doesn't do that. Good luck.

 

[captplaid]

I thought JD brakes were supposed to do that

 

[turbo466]

maybe check the linkage between the engine and pump. I have already seen them come loose and rattle around

 

[3Bladz]

I have had the brake pads desinigrate and plug the suction filter on the internal pump. It was really expensive to part the tractor to repair the pump. That pump provides fluid for the steering and power brakes and to the main pump up front I think. The 3 point lift will chatter like that after sitting until fluid gets pressure thru the system. Make sure you don't start it with the clutch depressed as that pump is after the clutch on this model and it won't get oil to the front pump. That was one of the major changes going to 44 series.

 

[radman1]

Are you talking about this 4320? http://www.kellnet.com/tractor/images/Picture030.jpg

Or the CUT 4320?
http://imagenes.solostocks.com/z1_4109781/2007-john-deere-4320-tractor.jpg

 

[3Bladz]

Are you talking about this 4320? http://www.kellnet.com/tractor/images/Picture030.jpg

Or the CUT 4320?
http://imagenes.solostocks.com/z1_4109781/2007-john-deere-4320-tractor.jpg

good point, I assumed a real 4320 since this is in the ag section.

 

[radman1]

good point, I assumed a real 4320 since this is in the ag section.

I assumed the bigger tractor as well. JD does have a couple of models of tractors with the same number although 30+ years apart. Same with some sprayer models and CUTs.

 

[jenkinsph]

I assumed the older 4320 since he asked about the brakes surging, the older model had hydraulic brakes the new 4320 CUT had mechanically applied brakes.




Shhould point out that the OP has not replied since Nov 9 2010.