I'm sure this has been hashed out many times but here goes: My much used 743b has developed an issue in which the left side does not pull as well as it should. The machine used to creep a little in neutral and there was also some noise coming from the drive train while in neutral and right after startup that could be cured by moving the drive arms just a little ...( these symptoms don't seem to be happening any more) I could live with those problems but now things are a bit more serious. When going forward the machine veers to the left and when I move the left drive arm forward and let the right arm return to a more neutral position to get it going straight the machine slows a considerable amount. This is not a problem when going in reverse as it it pulls evenly then. Also, when sitting still, if push the left control arm forward nothing will happen up to a point and then it will jerk into gear. I have tried pushing against a tree on dry land just to see if both sides will spin and they do. I'm guessing this could be the left side drive motor and have read that I could swap the motors side to side to verify. I don't make living with this thing but do need it on my farm ... if it is a motor or pump .... can these things be rebuilt ... I really don't want to spend lots of money on it if I don't have to, Thanks, Rgoer
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Swapping motors will tell you if its a motor or pump. They can be re-built, and they aren't that expensive.
The thing that does concern me a little is the fact you mention you move the stick for a while before it starts moving. This could be as simple as worn linkages and bushings, make sure they are all tight, all the way to the pump. If not, its pissibly a pump issue, but deal with that later if swapping drive motors does not make the problem move to the opposite side. Drive motors are easier and cheaper than the pump.
The thing that does concern me a little is the fact you mention you move the stick for a while before it starts moving. This could be as simple as worn linkages and bushings, make sure they are all tight, all the way to the pump. If not, its pissibly a pump issue, but deal with that later if swapping drive motors does not make the problem move to the opposite side. Drive motors are easier and cheaper than the pump.
Tazza ... Thanks for the feedback. I'm certainly hoping it's not the pump. Just curious, since it pulls evenly in reverse, could it still be the pump. Again, just wondering ... I know very little about the hydraulics on these things, Thanks again
Even when in reverse sounds like the pump is in good shape, it sounds more like a linkage issue than a motor/pump one.
You state it can spin the wheels, which they all should be able to do.
Check the linkages, see what they look like and go from there.
Thanks for the input Tazza ... one more symptom that I noticed today while I was running it: when going forward and it starts veering to the left, I pull back on the right control arm to straighten it and then the left side starts engaging and starts pulling much better. This makes me wonder if there is some "balancing" valve somewhere that my not be functioning correctly. Or as you say, it could be the linkage ... although I did visually check it today and I don't see anything obvious ... but again, I'm am no expert. Thanks again for your help, Roger
There is no valve as such, it's just manual linkages, its as if something is sloppy along the way, especially as you mention some times it gets better.
I agree that if it is hesitating before moving , doesn't pull the same or at all on one side then you need to disassembly that travel motor and you will probally find the orings and back up rings disenergrated , if you want an easier test then try and check the rock filter and you will probally find some chunk of o ring in it
Thanks for all the input guys ... I have noticed a hydraulic leak ... so I plan to swap the motors from side to side .... will not be able to work on it this week but will post what I find out when I get the motors swapped ... thanks again for all the help, Roger
All, I've finally had some time to spend on the loader and have been working on getting the drive motors swapped. So far I've got all the hoses and mounting bolts removed from the left side but I cannot get the motor off. I have pried it with a 2x4 and even placed some pressure on it from under neath with a jack ... it is moving just a little but I cannot pull it off. Is there a secrete or a proper way to remove it ? Thanks for any help, Roger
It should just slide out...... I didn't think there was anything holding it into place.
Hopefully another member can help, i have never worked on a 743B, but its the newer motor setup and should just slide out like the others do.
All, I finally got the motors swapped (had to use a ratchet strap to pull them out). Now the mystery, since swapping the motors from side to side the machine operates perfectly ... pulls evenly on both sides. Any opinions, comments or experiences as to why this may be. Thanks for all the input, Roger
Very odd. I wonder if a shuttle valve in the motor could have been stuck or something and the knocking and pulling of the motor got it to free up? There is no problem leaving the motors on the opposite sides. If it works, leave it be
Well, the mystery is not such a mystery. I did some more "test driving" the skidsteer today and it turns out the original problem did follow the drive motor. What had fooled me is that the machine does drive corectly when going forward, but today I tried it out in reverse and now I'm getting the same problem I had before only this time its in reverse (forward is fine) and its in the same motor. I guess when swapping the motors the hydraulic connections get reversed since the motor is rotated 180 deg. Anyway, now I will see if that motor can be rebuilt. I plan to change the hydraulic fluid and filter while its down ... what fluid does you all suggest. Thanks, RogerVery odd. I wonder if a shuttle valve in the motor could have been stuck or something and the knocking and pulling of the motor got it to free up? There is no problem leaving the motors on the opposite sides. If it works, leave it be
The drive motors are easy to service. Parts are available if required.
I personally run engine oil in my hydraulic system, but if you are in a cooler climate, you should probably go for a lighter grade like AW46. The colder it gets, the thicker your oil is at startup.
memphisdoug
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- Mar 19, 2010
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- 15
I just had the same problem you are describing with my 873. It turned out to be bad seals in the drive motor. We took it apart, put a new seal kit in it and it runs great now. Be prepared for a surprise on the cost of the seals. The seal kit for my motor was about $250 at the local Bobcat dealer. You don't get a whole lot for your money.
Fortunately (for me anyway), the seal kit (from "loader parts source") for a 743b is right at $100 and luckily my motor matches the one for the kit. They do however mention that there is another seal not included in that kit that is only available from Bobcat. They say that if you are getting oil in the chain-case that one also needs to be replaced. While I'm not sure that I need the seal now, I am just wondering if that is something I should replace now regardless of its shape while I have the motor out. Any comments welcome, Roger
If your oil level in your chain case is correct, don't worry about it. You won't know which one is leaking anyway. The seal they are talking about is the one that seals the chaft that goes into the chaincase. With the motor off, you will see the seal mounted into the drive motor carrier on the chain case.
All, I've rebuilt the motor and its back together. One question for anyone that has a rebuild manual or otherwise just knows: there are 4 hex bolts (big allen screws) that hold the 3 plates of the motor together ... does anyone know what torque those 4 bolts needs to be tightened to. Thanks for any help, Roger
