I have a 6430 and it is running a little warmer than normal water temp and then the hydraulic temp gets real hot and won't cool back down with a bush hog behind it. I took it to the John Deere dealer and the guy there said he thinks its the air pump in the transmission. And then said would be about 5K to fix it. Does this sound right? Would just like a second opinion. I know you would need to check it out to be sure but I was just wanting to know if this sounds logical. Thanks,,, Mark
 
the 6430 uses coolant to cool hyd oil. it sounds more like a problem with the cooling system [antifreeze low fan clutch] and it depends on the trans type on the cooling system it has.
 
I would check the fan clutch,,you can get a lock up kit (2 little brackets to tie the fan to the clutch) for 60 series,,not sure on that unit,,and I think there is an air pump in the transmission that "could" cause this too...It is part of Deere's Build to fail line of thought..
 
I'd be curious to see if the main hydraulic pump is staying at stall pressure, thinking it has to supply a function
 
There is an air pump to help move oil through the cooler and if it failed that will cause the oil to over heat. Also there are two separated cooling systems one for the engine and one for the trans oil . Some tractors have a valve at the front bottom of radiator you have to open to fill the trans cooler and some just have to keep radiator topped off. I would think the dealer would have checked that , you might ask , one of my guys can take the front cover off the trans. without splitting it to get to the air pump , still a pretty tough job
 
(quoted from post at 07:49:04 08/29/18) I'd be curious to see if the main hydraulic pump is staying at stall pressure, thinking it has to supply a function

It also sounds like the hydraulics are engaged just sitting and not moving or hooked up to anything. Noise kinda like when you turn the steering wheel.
 
(quoted from post at 07:49:09 08/30/18)
(quoted from post at 07:49:04 08/29/18) I'd be curious to see if the main hydraulic pump is staying at stall pressure, thinking it has to supply a function

It also sounds like the hydraulics are engaged just sitting and not moving or hooked up to anything. Noise kinda like when you turn the steering wheel.

Check "standby pressure", pump should kick down to 450? psi when there's no hydraulic demand.

I repaired a 6420 a couple of years ago that had scoring and damage to the stroke control hydraulic cylinder (inside the piston-type hydraulic pump) causing an internal leak, and dumping stroke control oil so the pressure compensator couldn't control pressure, and it would run all day long at 2750 psi, causing noise and oil heating.

Replacing the pump solved the problem.

Dealership threw $5000 at it, and never figured out the problem.

That being said, apparently some 6430's must have had open-center hydraulics, the Parts Catalog shows a couple of fear pumps, as well as the piston pumps???
 

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