john deere 2640 no hydraulics when resarting hot

cowman79

Member
I have a 1979 2640 and sometimes when I have been running the tractor for a while and shut the tractor off for a little while and restart it I have no hydraulic pressure. At start up I have pressure but only for a few seconds then I loose the steering, three point, and the remotes. After about thirty seconds or so I get pressure back and never have another problem with the hydraulics. When first starting the tractor cold the hydraulics work as they are supposed to. A little history on the tractor When I bought it 6 months ago it had just had the charge pump replaced and new brakes. I have drained the oil, replaced the filter and cleaned the screen. The screen was relatively clean but the was some material in the old fluid. almost a metallic haze. Not sure if this was remaining debris from the previous owners repairs. I am not sure what I need to check at this time.
 
Metallic is from worn out brakes. A maqgnet in the screen will help.
Check valve is probably laying in a drain pan somewhere.
 
(quoted from post at 18:22:59 07/08/14) Metallic is from worn out brakes. A maqgnet in the screen will help.
Check valve is probably laying in a drain pan somewhere.

I was thinking the metallic was from the previous brakes coming apart. Where would this check valve be located. Also it seems to me like when the oil is hot is all drain back to the sump. Is this even possible.
 
Hydraulic lines out of lower right front of tran to hyd pump.
Tx Jim will probably help you w/part pics.
 
Check valve that D- referred to is parts keys 40-42(2nd photo). I think check valve isn't the hyd problem as check valve is to prevent hyd oil drain back during extended non-running periods of time.

I think your tractors hyd problem is a worn/pitted stroke control valve(parts key 42 & 43 1st photo) seat in frt hyd pump caused by the tiny metal particles.
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(quoted from post at 07:04:14 07/09/14) Check valve that D- referred to is parts keys 40-42(2nd photo). I think check valve isn't the hyd problem as check valve is to prevent hyd oil drain back during extended non-running periods of time.

I think your tractors hyd problem is a worn/pitted stroke control valve(parts key 42 & 43 1st photo) seat in frt hyd pump caused by the tiny metal particles.
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Can this be removed and check easily.
 

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