Bobcat 632, hydraulic oil problem

[PA.Johansson]

Hi, My bobcat 632 is somehow leaking oil from the rims.(I don't know the English word for it, but the rims on one side of the machine is leaking more than the other side.) A few months back I made a total repair of the hydrostatic pumps, but the drive motors are old I think. And it's kinda weak on one side. When I bought the machine it wasn't moving at all on the right hydraulic motor for the wheels. We opened it from the outside and found a spring that was broken, we replaced it with a different spring. Since then it has been working, but I think the spring i put there isn't strong enough. Can this cause problems with the strength of the hydraulic motor? This is one of my problems... Also, the old owner didn't tap the oil hoses when he removed the hydrostat, so one of the hydraulic motors didn't rotate at all when I got the machine. Somehow it started to move later in the process.. Is it possible to repair these somehow? Now, the second problem, the hydrostatic oil is somehow leaking into the gearbox(or what's it called...? With the brakes..) and then out through the rims. Is there any way to fix this problem without removing the hydrostat again? With regards, Anton

 

[Tazza]

You are talking about the axle seals. Over time they do tend to leak a bit. To do this repair, you have two choices if they are the rear ones. One is to remove the pump and engine, the other is to drop the chain case and roll it out to work on it.
The spring could be an issue, how close was it to the other one that was there? it should be the same tension and length to work properly. This spring holds two plates together that have oil running through them, if one side is weaker, it could allow the plates to seperate slightly letting oil by-pass.
Now, oil leaking into the chain case is usually the seals where the drive motor shaft goes into the gearbox. With the drive motor off, you will see a seal that seals against the shaft that the splined shaft from the drive motor goes into. Give this shaft a wiggle, make sure it has no movement. Any movement will damage the new seal.

 

[PA.Johansson]

You are talking about the axle seals. Over time they do tend to leak a bit. To do this repair, you have two choices if they are the rear ones. One is to remove the pump and engine, the other is to drop the chain case and roll it out to work on it.
The spring could be an issue, how close was it to the other one that was there? it should be the same tension and length to work properly. This spring holds two plates together that have oil running through them, if one side is weaker, it could allow the plates to seperate slightly letting oil by-pass.
Now, oil leaking into the chain case is usually the seals where the drive motor shaft goes into the gearbox. With the drive motor off, you will see a seal that seals against the shaft that the splined shaft from the drive motor goes into. Give this shaft a wiggle, make sure it has no movement. Any movement will damage the new seal.

Hi, Thanks for the help! The spring was pretty close to the old I think. Since the spring was in small pieces because of rust, I didn't know how strong it was. Could the springs cause problems and make the machine weak? I've seen videos where people stand still with the bobcat and rotate the whole machine- this is something I can do without a bucket, but with the bucket it's really hard to turn. When I opened one of the drive motors I kinda opened it and the shaft was still mounted to the gearbox. Do I see the seal if I open it this way or do I have to remove the whole thing? (It's really something I don't want to do again right now..... ) somehow it feels wrong to buy new drive motors, they will cost more than what I paid for it. I've found a site called loader part something.. Have you or anybody else got any experience with the stuff they're selling? Here in Sweden one drive motor cost approximately 2900$ for one drive motor. The one I opened had got a little rust on it, could this be doing any of the problems..? But the side I opened is still stronger than the other side. Or could I just buy a new shaft/bearing thingy..? That's all my questions for now... /A

 

[PA.Johansson]

Hi, Thanks for the help! The spring was pretty close to the old I think. Since the spring was in small pieces because of rust, I didn't know how strong it was. Could the springs cause problems and make the machine weak? I've seen videos where people stand still with the bobcat and rotate the whole machine- this is something I can do without a bucket, but with the bucket it's really hard to turn. When I opened one of the drive motors I kinda opened it and the shaft was still mounted to the gearbox. Do I see the seal if I open it this way or do I have to remove the whole thing? (It's really something I don't want to do again right now..... ) somehow it feels wrong to buy new drive motors, they will cost more than what I paid for it. I've found a site called loader part something.. Have you or anybody else got any experience with the stuff they're selling? Here in Sweden one drive motor cost approximately 2900$ for one drive motor. The one I opened had got a little rust on it, could this be doing any of the problems..? But the side I opened is still stronger than the other side. Or could I just buy a new shaft/bearing thingy..? That's all my questions for now... /A

If somebody wants to se pictures of the repair I made on it, go to this page: http://www.maskinisten.net/viewtopic.php?f=99&t=105401&p=1301271#p1301271 It's a Swedish forum for tractor owners..

 

[jerry]

If somebody wants to se pictures of the repair I made on it, go to this page: http://www.maskinisten.net/viewtopic.php?f=99&t=105401&p=1301271#p1301271 It's a Swedish forum for tractor owners..

The pictures are amazing, you started with a pile of junk and ended up with a nice looking machine. Well done.

 

[OldMachinist]

The pictures are amazing, you started with a pile of junk and ended up with a nice looking machine. Well done.

In the picture of the hydrostatic pump there is a large square port block. Behind the middle fitting on the left side is a bronze filter. It may be clogged and causing some of the weakness.
Also check to see if the chaincase is overfull. Some of the axle leakage could from this.

 

[Tazza]

In the picture of the hydrostatic pump there is a large square port block. Behind the middle fitting on the left side is a bronze filter. It may be clogged and causing some of the weakness.
Also check to see if the chaincase is overfull. Some of the axle leakage could from this.

Loader parts source is great to deal with, they know their stuff.
OM makes a good point, if there is a block on the hydraulic pump, there is a hidden bronze filter that causes lots of issues if it is dirty.

 

[PA.Johansson]

The pictures are amazing, you started with a pile of junk and ended up with a nice looking machine. Well done.

Thank you Jerry! I worked two months with that, and i'm really satisfied with the result.