2640 brake help needed

cowman79

Member
I just replaced a right brake line on my 2640. At this time I also replaced the o-rings in the brake valve. I am having trouble building pressure when pushing the pedal down. I have read a couple of different things about the brakes on these tractors. I am unsure if they are power hydraulic brakes or not. With this I am unsure how to bleed the brakes. Any help would be greatly appreciated.
 
JD utility tractors similar to your 2640 have hyd brakes with the brake valve reservoir filled by a passageway in trans housing being supplied by trans pump pressure of around 160 psi. One should bleed each side similar to auto or pickup.
 
(quoted from post at 15:12:26 02/22/15)
JD utility tractors similar to your 2640 have hyd brakes with the brake valve reservoir filled by a passageway in trans housing being supplied by trans pump pressure of around 160 psi.

So what's the best method for bleeding the brakes.
 

Put a clear hose on bleeder,with engine running step on one pedal,open corresponding bleeder,when pedal bottoms out then close bleeder,repeat procedure until no air bubbles are seen in clear hose
 
(quoted from post at 15:23:37 02/22/15)
Put a clear hose on bleeder,with engine running step on one pedal,open corresponding bleeder,when pedal bottoms out then close bleeder,repeat procedure until no air bubbles are seen in clear hose


it appears I can only pump air and not fluid. I have pumped the pedal and bled and I Only get air and am never getting fluid or pressure at the pedal.

I am wondering if there is a valve that is sucking air on the brake valve and not pumping fluid.
 

remove RH footrest then remove plug(parts key 6) to determine if reservoir is full. If reservoir is full then there is a faulty valve in valve housing.
mvphoto16658.gif
 
(quoted from post at 17:43:34 02/22/15)
remove RH footrest then remove plug(parts key 6) to determine if reservoir is full. If reservoir is full then there is a faulty valve in valve housing.
mvphoto16658.gif

I took the foot rest off and there is no fluid in the reservoir.
 
I would check that the fill port is open. It is a pin hole sized orifice in the transmission housing and admits oil into the resevoir through the gasket (item #2 in Jims parts view) There is also a larger (easy to see) return port but the fill port is very small. I have seen these get blocked and give the symptoms you describe
 
(quoted from post at 19:04:53 02/22/15) I would check that the fill port is open. It is a pin hole sized orifice in the transmission housing and admits oil into the resevoir through the gasket (item #2 in Jims parts view) There is also a larger (easy to see) return port but the fill port is very small. I have seen these get blocked and give the symptoms you describe

I pulled the valve off and didnt see any plugged holes but I was in a hurry to put it back on since the oil was pouring out. I did put it back together and fill it with oil since I needed to use it today. This tractor has had the charge pump replaced before I bought it and the rear brakes replaced. But I have had times when the charge pump lost its prime and had to wait for it to build hydraulic pressure. I am concerned because I have changed the fluid and filter since I bought the tractor and it still has brake material in it. I hope that it is just residual left in the system from when the tractor was repaired but I am usually not that lucky.
 

cowman79
Now you know why you can't bleed your tractors brakes because of lack of oil in valve reservoir. But you'll need to determine what's blocking trans oil pressure passageway too brake valve in trans case.
 
(quoted from post at 07:34:58 02/23/15)
cowman79
Now you know why you can't bleed your tractors brakes because of lack of oil in valve reservoir. But you'll need to determine what's blocking trans oil pressure passageway too brake valve in trans case.

I would like to thank you for all or your help. The system makes sense to me now. Sometime when it's warmer and I can have the tractor down for a few weeks days I will pull the valve and check to see what's going on.
 

You're very welcome. Post an update after you determine what's blocking the trans oil pressure from getting to brake valve reservoir. IIRC the oil galley orifice is circled in red.
mvphoto16684.png
 

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