753 drives

[Tazza]

Just an update on this so far, keep in mind the my LH motor was the one playing up especially in reverse. I removed both the drive motors with the intention of swapping LH to RH and RH to LH and therefore isolating the issue to the LH Drive motor, or a pump issue further up the circuit. On the advise of a You-tube video, I disassembled LH drive motor to find 1 missing Inner O-ring, and 1 Centre O-ring perished and broken. Both of the plastic seal cover things had chips and nicks missing too, but the LH drive motor had no signs of being opened before indicating they were original seals. Then out of curiosity I thought I would inspect the RH drive motor as well and found all o-rings intact (Not original seals, have been replaced at some stage). The reason i disassembled the RH was to see if the RH seals were in the same condition as the LH seals, and therefore I could ignore the missing broken LH seals as the casue of the problem. Given that the good motor (RH) has intact seals, and bad motor (LH) has missing/broken seals im feeling confident new seals could fix it. However, my hydraulics guy has suggested that the missing and perished O-rings in the LH drive motor is not the root cause of my problems and wants me to remove the engie/pump to inspect the relief valve on the underside of the pump. I can understand his theory on this, but ill be replacing both Drive Motor seal kits and re-testing before the engine and pump comes out. Ill keep the forum updated on my progress but in the mean time has anybody else got a thought on this?

I had an early model 753 that had no power on one side, the wheels would spin, but put any load on it and it will stop. I cracked it open and the Orings turned to powder, the backup plastic rings were fine. I replaced the Orings and re-used the backups and that motor worked just fine.
I took the other motor off at the same time as i was going to do both sides as if one went bad, the other was likely to be the same, the Orings were perfect in that side, no signs of deterioration. Same colour so i suspect they had never been touched either. I put new seals in as it was opened. Seals cost all of $5 per side.
I'd do the seals and give it a go before pulling the motor.

 

[Old753]

I had an early model 753 that had no power on one side, the wheels would spin, but put any load on it and it will stop. I cracked it open and the Orings turned to powder, the backup plastic rings were fine. I replaced the Orings and re-used the backups and that motor worked just fine.
I took the other motor off at the same time as i was going to do both sides as if one went bad, the other was likely to be the same, the Orings were perfect in that side, no signs of deterioration. Same colour so i suspect they had never been touched either. I put new seals in as it was opened. Seals cost all of $5 per side.
I'd do the seals and give it a go before pulling the motor.

Genuine Bobcat sealkits have cost me $175AUD per side so far. Hoping this is the fix. Fingers crossed.

 

[Tazza]

Genuine Bobcat sealkits have cost me $175AUD per side so far. Hoping this is the fix. Fingers crossed.

Lets hope it does the trick.
Depending on the style motor you have, you may need to time it when putting back together.

 

[Old753]

Lets hope it does the trick.
Depending on the style motor you have, you may need to time it when putting back together.

OK, so I think I fixed it! Rebuilt both drive motor with new seal kits and also swapped left (Bad) motor to the right, and right (Good) motor to the left. Additional to the seal kits I replaced all the big drive motor hoses and cleaned the case drain filters. Since the repair I have done a total of two days work on the machine and it appears to be fixed. Although it was costly excercise including the new hoses, a have now fixed most of the oil leaks too. At least now I can confirm that it was not a pressure relief valve sticking in the pump which was going to require the engine to be removed! Thankis for every ones help.

 

[Tazza]

OK, so I think I fixed it! Rebuilt both drive motor with new seal kits and also swapped left (Bad) motor to the right, and right (Good) motor to the left. Additional to the seal kits I replaced all the big drive motor hoses and cleaned the case drain filters. Since the repair I have done a total of two days work on the machine and it appears to be fixed. Although it was costly excercise including the new hoses, a have now fixed most of the oil leaks too. At least now I can confirm that it was not a pressure relief valve sticking in the pump which was going to require the engine to be removed! Thankis for every ones help.

Glad it appears to be fixed.
Drive motor hoses are expensive, they are high pressure but at least you know they will be good for some time now.

 

[Neal]

OK, so I think I fixed it! Rebuilt both drive motor with new seal kits and also swapped left (Bad) motor to the right, and right (Good) motor to the left. Additional to the seal kits I replaced all the big drive motor hoses and cleaned the case drain filters. Since the repair I have done a total of two days work on the machine and it appears to be fixed. Although it was costly excercise including the new hoses, a have now fixed most of the oil leaks too. At least now I can confirm that it was not a pressure relief valve sticking in the pump which was going to require the engine to be removed! Thankis for every ones help.

I have the same issue u was just getting ready to pull the motor an pump the seals you're talking about are inside the gerola drive motor correct?before i replaced the carrier seals between the drive motor an the chain case it was fine now that I did that about a 3 hours later my reverse is almost not there so I replaced the shuttle valve an poppets but it's still the same I am some what hand with a wrench but get nervous tearing precise parts like the motor apart but if you think it's something not to hard I would like to try it

 

[Old753]

I have the same issue u was just getting ready to pull the motor an pump the seals you're talking about are inside the gerola drive motor correct?before i replaced the carrier seals between the drive motor an the chain case it was fine now that I did that about a 3 hours later my reverse is almost not there so I replaced the shuttle valve an poppets but it's still the same I am some what hand with a wrench but get nervous tearing precise parts like the motor apart but if you think it's something not to hard I would like to try it

Yeah, I was told I needed to remove the engine and pump to fix my issue, so glad I didnt. Very unfortunate that you have to remove the drive motor for a second time, its not an enjoyable job. As for replacing the drive motor seal kits it is nothing to be scared of, its only a couple of o'rings and nylon/plastic cups. These are my suggestions (which I learnt from others, or by making mistakes myself) to ensure it all goes smoothly. 1. Mark all the sections of the housings with a punch to ensure they go back in the same orientation. 2.Be careful not to loose the 2 ball bearings that fall out when you seperate the , they fall out if you turn it upside down. 3. Buy an oil stone and gently clean up all the mating surfaces. 4. clean eveything meticulously before re-assembly.

 

[Neal]

Yeah, I was told I needed to remove the engine and pump to fix my issue, so glad I didnt. Very unfortunate that you have to remove the drive motor for a second time, its not an enjoyable job. As for replacing the drive motor seal kits it is nothing to be scared of, its only a couple of o'rings and nylon/plastic cups. These are my suggestions (which I learnt from others, or by making mistakes myself) to ensure it all goes smoothly. 1. Mark all the sections of the housings with a punch to ensure they go back in the same orientation. 2.Be careful not to loose the 2 ball bearings that fall out when you seperate the , they fall out if you turn it upside down. 3. Buy an oil stone and gently clean up all the mating surfaces. 4. clean eveything meticulously before re-assembly.

Ok thanks for the tips really do appreciate. Where did you get your seal kit ( o rings and plastic cups) do I have to go through bobcat?

 

[Tazza]

Ok thanks for the tips really do appreciate. Where did you get your seal kit ( o rings and plastic cups) do I have to go through bobcat?

Bobcat or loader parts source for seal kits.
If just the Orings were bad, a seal shop will help you out, but the plastic backups, you need the kit

 

[Neal]

Bobcat or loader parts source for seal kits.
If just the Orings were bad, a seal shop will help you out, but the plastic backups, you need the kit

Ok thanks for all the info have a good new year I will order them through bobcat an post the results here after everything is done I am a when I get a chance type guy so be patient with me hahahaha

 

[Jerv753]

Lets hope it does the trick.
Depending on the style motor you have, you may need to time it when putting back together.

What do you mean by time it??

 

[Jerv753]

Lets hope it does the trick.
Depending on the style motor you have, you may need to time it when putting back together.

What do you mean by time it ? Thanks