Bobcat 743B oil in chain case??

[hunter29078]

I have read the procedure for changing the seal between the drive motor and chaincase. My question is what do I need to look for and what parts do I need. If the drive motor is leaking into the case do I need to rebuild the drive motor or just replace that seal and how do you know? If it is just the seal do I only need to buy the big seal on the chaincase? Thanks.

 

[doger5]

I know when you change the seal on the chain case there is a quad seal behind this seal that should be changed as well .

 

[Tazza]

I know when you change the seal on the chain case there is a quad seal behind this seal that should be changed as well .

No need to rebuild the motor, the case drain end is open, that's what the seal to the chain case is for. I didn't think about the quad ring, but it's there and should be changed too.
Not sure if the B model has case drain filters, look for aluminium cans on the case drain lines. If they get plugged, they will increase the pressure and blow out the seal.

 

[hunter29078]

No need to rebuild the motor, the case drain end is open, that's what the seal to the chain case is for. I didn't think about the quad ring, but it's there and should be changed too.
Not sure if the B model has case drain filters, look for aluminium cans on the case drain lines. If they get plugged, they will increase the pressure and blow out the seal.

Ok thanks. I will try to post pics as I go with it for future reference.

 

[hunter29078]

Ok thanks. I will try to post pics as I go with it for future reference.

Ok, for future reference the 743b sn 509318001 and above will need the part numbers and quantity (2) 6705874 Seal and (2) 58K243 o-ring This will stop oil leaking into the chain case. If the old plastic seal is in there just grab one of the ribs with vise grips and pull it out. There is an o-ring inside that supposedly is no longer needed, however I left it in. Then put the seal in black side facing out and push it. I coated it with oil to help. Once the center part is on the shaft I used a short piece of 3" pvc pipe to tap it in the rest of the way. If oil in the chain case is weeping by the seal then it is not in far enough. Also if the chain case is full of oil as mine was then you can remove the hydraulic motors and see which seal is bad, as oil will be pushing past it out of the chain case, if no oil is coming out when the motor is removed then the seal is functioning properly. The o-ring is put on the the hydraulic motor before re-installing. I use oil on the o-ring to help install as well. The procedure for this is pretty straight forward, but there is no quad seals on the newer 743s as there was in older ones.

 

[Tazza]

Ok, for future reference the 743b sn 509318001 and above will need the part numbers and quantity (2) 6705874 Seal and (2) 58K243 o-ring This will stop oil leaking into the chain case. If the old plastic seal is in there just grab one of the ribs with vise grips and pull it out. There is an o-ring inside that supposedly is no longer needed, however I left it in. Then put the seal in black side facing out and push it. I coated it with oil to help. Once the center part is on the shaft I used a short piece of 3" pvc pipe to tap it in the rest of the way. If oil in the chain case is weeping by the seal then it is not in far enough. Also if the chain case is full of oil as mine was then you can remove the hydraulic motors and see which seal is bad, as oil will be pushing past it out of the chain case, if no oil is coming out when the motor is removed then the seal is functioning properly. The o-ring is put on the the hydraulic motor before re-installing. I use oil on the o-ring to help install as well. The procedure for this is pretty straight forward, but there is no quad seals on the newer 743s as there was in older ones.

Good work on getting yours fixed and for sharing the seal numbers to do the job.