722 Drive Motor Problem

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ChandlerW

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Oct 8, 2013
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My drive motor on the right side of my skid steer came apart. I bought a new rotating unit and installed it. I checked the drive pump for any obstructions and I dug the remains of the previous owners bearing failure out of the chain case.
Everything is back together but the right side will not drive. The left side will drive forwards and backwards.
I took off the chain case covers and the left side doesn't show any oil flying around when the motor is idling and the left stick pushed back and forth.
The right side has a steady stream of oil coming from a hole in the drive motor. The hole is there from the factory. Its a perfectly drilled round hole.
Anyone know what I'm dealing with here? I can't find anything in the manual.
 
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ChandlerW

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Oct 8, 2013
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So here's an update. Apparently these holes are supposed to be here for drainage. But the opposite side that is working does not have any fluid draining at all. The right side has fluid draining and is not working.
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antfarmer2

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Oct 28, 2013
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So here's an update. Apparently these holes are supposed to be here for drainage. But the opposite side that is working does not have any fluid draining at all. The right side has fluid draining and is not working.
Could you have put your lines on backwards?
 
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ChandlerW

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Oct 8, 2013
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Or a stuck open pressure relief valve?
I just switched around the replenishing / high pressure relief valves. No difference. I had the hoses swapped the wrong way around with the left drive motor. I switched them and now forward = forward and reverse = reverse.
The only difference is that there is a gush of oil coming from the motor in the right chaincase, and that drive motor doesnt work. There is no gush of oil in the left chain case and it works.
The manual shows a hole in the drive motor for "case drain and supply". I'm guessing the gush of oil is not supposed to be happening.
 

antfarmer2

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Oct 28, 2013
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I just switched around the replenishing / high pressure relief valves. No difference. I had the hoses swapped the wrong way around with the left drive motor. I switched them and now forward = forward and reverse = reverse.
The only difference is that there is a gush of oil coming from the motor in the right chaincase, and that drive motor doesnt work. There is no gush of oil in the left chain case and it works.
The manual shows a hole in the drive motor for "case drain and supply". I'm guessing the gush of oil is not supposed to be happening.
Did you try swapping the motors to see if the problem follows? Are the seals good and did you seal the threads whe you assebled
 
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ChandlerW

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Oct 8, 2013
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Did you try swapping the motors to see if the problem follows? Are the seals good and did you seal the threads whe you assebled
I didn't swap out the motors. I guess I'll do that tomorrow. Thats a pretty big job. But I want it fixed.
 

jerry

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May 3, 2007
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2,043
Must have some sort of seal or oring could they have been eaten?
Since it is a piston motor does it have a wear surface that the pistons run on like in piston pump? If there were any grooves in that surface I could see it not working.
 

Tazza

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Dec 7, 2004
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Since it is a piston motor does it have a wear surface that the pistons run on like in piston pump? If there were any grooves in that surface I could see it not working.
As the manaul says it is a piston type, there has to be something else wrong.
There shouldn't be much oil coming from the case drain hole, especially when not under load. I would suspect a seal or something, i have not worked on a piston motor though.
Could you have put something in backwards? are there any seals to hold most of the oil back, except for the case drain fluid?
 
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ChandlerW

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As the manaul says it is a piston type, there has to be something else wrong.
There shouldn't be much oil coming from the case drain hole, especially when not under load. I would suspect a seal or something, i have not worked on a piston motor though.
Could you have put something in backwards? are there any seals to hold most of the oil back, except for the case drain fluid?
I may have put the swash plate in backwards. The manual isn't real clear on that.
 
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ChandlerW

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Oct 8, 2013
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I may have put the swash plate in backwards. The manual isn't real clear on that.
I did a search for swash plate and ended up reading a lot of threads with similar problems. I think the answer is to pull the drive and check the condition of the swash plate. I may as well pull the pumps and check them too.
 

antfarmer2

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Oct 28, 2013
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I did a search for swash plate and ended up reading a lot of threads with similar problems. I think the answer is to pull the drive and check the condition of the swash plate. I may as well pull the pumps and check them too.
If the plates have small groves in them Tazza has a trick with a piece of glass and sand paper can fix it cheap
 
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ChandlerW

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Oct 8, 2013
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If you put them in backwards that could do it
I decided to switch out the drive motors to see if the problem is with the motor or pump. Its going to be a lot easier than pulling the pump assembly. There isn't much time during the week to work on it but I'll try to find some hours.
As for the swash plate. One end had a chamfer. The other end was 90 degrees. I believe I installed the chamfer away from the rotating group pistons. Was this the right way or the wrong way?
 

Tazza

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I decided to switch out the drive motors to see if the problem is with the motor or pump. Its going to be a lot easier than pulling the pump assembly. There isn't much time during the week to work on it but I'll try to find some hours.
As for the swash plate. One end had a chamfer. The other end was 90 degrees. I believe I installed the chamfer away from the rotating group pistons. Was this the right way or the wrong way?
I would have thought chamfer towards, but i have not pulled one down.
As you have a lot of oil coming from the case drain hole, it has to be something internal of the motor..... Just not sure what.
I would suspect the chamfer should be towards the rotating group, but i can't be sure. The only way to know for sure is to look at the other one that you have not opened.
 

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