743 good or bad

[6620]

New issue!! I was using the 743 the other day and the hydrolics got slow at lifting loads of rock into my dump trailer. It would lift so far and just stop. If you wait a minute, then hit the foot pedal. it would lift a little more. I thought maybe I had to heavy a load in the bucket. Then a day later, I got in it to move it. the boom and bucket would not move at all. I was able to get the bucket off. Then I got it limped to the trailer and had no moving power at all. You could go full throttle or idle. When you pull back both sticks, it would make a lurch, however, you didn't know which side was going to move. All you got was a lurch forward or back. Then you just hoped for the next lurch to go the direction you wanted. Would it be possible for the hydrolic filter to be that plugged? Thanks for any suggestions.

 

[Markle]

Shall we assume you are not low on hydr fluid?

 

[Davross22]

Shall we assume your main filter isnt clogged?

 

[6620]

Shall we assume you are not low on hydr fluid?

I don’t think it was. I check the sight glass on the side of the machine.

 

[6620]

Shall we assume your main filter isnt clogged?

Main filter, do you mean the hydraulic filter above the battery? I asked the guy that is supposed to be working on it, he claims that can’t be it. Can it??? Or is there another filter I don’t know about? Thanks

 

[6620]

new information: hydrolic filter was changed, old filter has filings in it. and we have no charge pump pressure. So we are going to pull out the main pump and see what it looks like. If there is a different direction we need to go, please tell me. Thanks

 

[6620]

Found it. Vein pump. lost a chunk out of it and it broke the shaft. thanks for all your help.

 

[dfb]

Thank you for posting the follow up fix.

 

[6620]

Just a question. What would happen if you put a magnet in the hydraulic tank? On a wire so you can pull it out from time to time??

 

[foton]

I do not believe it would hurt anything as long as it stayed put, if there is a drain plug in the bottom of the hydro tank , see if you can pick up a drain bolt with a magnet fused into it. but I think all will agree a good everything cleaning is necessary before the new pump is installed. the magnet should be for particles that were missed. I have heard of people strapping rare earth magnets on the outside of the hyrdo filters also as a just in case thing. I think I would do a not to many hours on it fluid change after pump exchange and inspect fluid condition also. good luck

 

[Sapientoni]

If there's air in the hydraulic system, the bucket won't respond smoothly to the inputs. It will stall a little at pressure points until the air pressure is sufficient to overcome the loss created by the air. Then the bucket will jump a little.

 

[Sapientoni]

On my old 610 after rebuilding the leaking cylinders, I lift the boom up and loosen the pressurized hose on each cylinder as they were rebuilt. When the blowout and bubbling stop, I tighten them back. It's a bit messy but what 'ya gonna do? The bit of residual air just has to work itself out and is usually not noticed. Crude but effective. Just do that in a place where you don't mind a little oil. a dusty part of the driveway or where you can zipsorb it.