No oil pressure

   / No oil pressure #1  

willhoff

New member
Joined
Jul 23, 2013
Messages
21
Location
new concord, ohio
Tractor
john deere
I have a JD 6405 with a SyncroPlus Transmission. The transmission had 75 psi of oil pressure which is low. I pulled the transmission. Everything looks good so I put a new pump, seals, O-ring in the unit and put it back together. I started the tractor everything worked good. I shut the engine off and topped the transmission oil off then started the tractor again. It wouldn't move. I have zero oil pressure. I pulled the transmission again and everything looks good. Any Suggestions??
 
   / No oil pressure
  • Thread Starter
#3  
Air pocket in system (cavitation in pump?), any way to purge the pump and lines?

Dale

I didn't hear the pump cavitating when it was running and the pump was working for a time. The oil pressure check point is basically beside the pump so there is no oil lines to bleed. I wouldn't think air could be trapped in this system.
 
   / No oil pressure
  • Thread Starter
#5  
Relief valve stuck open?

It looks like there is two valves that regulate the oil pressure in that transmission. It has a Pressure Regulating Valve and a Engagement Override Valve. I disassembled both valves. The spools where clean, no marks or scratches and they moved freely in their ports. The springs looked good and they measured the specified length. I don't have a way to test pounds of torsion on the springs but I was satisfied they are not at fault and put the valves back together.
 

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