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Help- 720 hydraulics quit!

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scottAR

10-07-2002 19:29:05




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Going thru the field pulling a 3 pt implement and then it wouldn't raise. Took the pump apart, no keys sheared, fan turns, governor turns, and removed the freeze plug at the end of the pump shaft and it turns. Where is my problem? Could the pump loose suction while running? Even put air pressure in the reservoir and that doesn't help. Fluid level full and no remote pressure either.




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scottAR

10-08-2002 17:47:56




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 Re: Help- 720 hydraulics quit! in reply to scottAR, 10-07-2002 19:29:05  
Thanks guys, that gives me other things to try.



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Clooney

10-08-2002 03:21:13




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 Re: Help- 720 hydraulics quit! in reply to scottAR, 10-07-2002 19:29:05  
Scott, use the remotes hydraulic handle & listen for the pump noise to increase or the engine load to change, if so your problem is probably in the rockshaft control or a stuck valve. If you don't hear a pump noise or engine load increase suspect a stuck pressure relief valve or pump problem.
~While you could have an air locked pump I haven't ever seen that happen to a system that is being used at the time of the failure.
~You might want to pull the top cover on the rear housing to see if you can see the oil spraying out anywhere.
~You might want to also check the suction side lines for cracks or pin holes, it doesn't take much of a leak on the inlet side to keep the pump from picking up oil.
~Did the 3-point implement hit anything & jump before the failure? If so suspect a stuck pressure relief valve.

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scottAR

10-07-2002 19:31:39




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 Re: Help- 720 hydraulics quit! in reply to scottAR, 10-07-2002 19:29:05  
Forgot to say it's 720LP not a diesel.



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MIKE HANLEY

10-07-2002 20:25:58




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 Re: Re: Help- 720 hydraulics quit! in reply to scottAR, 10-07-2002 19:31:39  
On the Diesels with the pump under the tractor, oil will run into the pump from the tank. On tractors with the pump running off the governor, the pump is high and hard to prime. If the oil level gets too low and for some reason the pump loses it primp it will "air lock". Most of the time it will work if you put oil in the pump after it is mounted but before you put on the oil lines. I have had this not work once in a while and then after it is all together and with proper oil level jack the 3pt to the raised posisition with the tractor running and the lower the 3pt. This will then shoot oil into the pump

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