Predator swap done

[bobby blaize]

When you say "screw hole in the chain case" where is this screw hole? The only holes in the chain case should be the inspection port in front and the access panels on top of the chain case.

If the oil is coming out of the top access panels then you most likely have bad motor carrier seals.

Thanks.

It is the access plate. I will pull the motors and replace the shaft seals. Thanks for the info. I found another thread with the seal
part number (#6705847).

I only had one of the motors off and put o-rings in it that were missing. The previous owner didn't know anything about bobcats and put everything together wrong or without the seals. I should have known that the only piece I didn't pull apart would also be put together wrong since apparently they had the entire bobcat apart.

 

[bobby blaize]

So your hydraulic tank level is getting lower over time, no visible leaks to the inside or outside of machine? Drive motor seal compromised and leaking into chain case it seems. I don't know any other way the chain case fluid level would be increasing, unless water getting in and mixing into a milky slurry.

Thanks. Pretty sure it's the shaft seal. I have them on order and will update after that is fixed. Hopefully this will be the last surprise with the hydraulics and I can actually run the bobcat and test the motor swap.

 

[brdgbldr]

Thanks.

It is the access plate. I will pull the motors and replace the shaft seals. Thanks for the info. I found another thread with the seal
part number (#6705847).

I only had one of the motors off and put o-rings in it that were missing. The previous owner didn't know anything about bobcats and put everything together wrong or without the seals. I should have known that the only piece I didn't pull apart would also be put together wrong since apparently they had the entire bobcat apart.

Here is a link to the parts catalog so you can look up parts with the model number or serial number of your machine instead of digging through threads:

https://partscatalog.bobcat.com/

 

[bobby blaize]

Seals arrived and I pulled the drive motor off one side. The shaft seal was in the bore and I couldn't tell if it was sealing properly so I pried it out. The replacement seal is way bigger than the existing seal. The machine says it's a 743, but almost all of the parts I have ordered have been wrong including this seal.

The pictures show the drive motor apart (3 pieces and a shaft) and the seal that goes around the shaft. I measured the ID and OD of the seal I pulled out and ordered a new one based on the measurements because I can't find the right part from BobCat.

Can anyone identify the model number of the machine based on the drive pump?

 

[bobby blaize]

When I look up the number on the drive motor 7E20 it shows up as a 743 drive motor so why is the replacement seal different? Even in the 743 manual it shows the larger seal. Could it be a different chain case? The selector valve is also different so I am wondering if this machine is a pieced together machine from different years/models?

 

[brdgbldr]

When I look up the number on the drive motor 7E20 it shows up as a 743 drive motor so why is the replacement seal different? Even in the 743 manual it shows the larger seal. Could it be a different chain case? The selector valve is also different so I am wondering if this machine is a pieced together machine from different years/models?

It is possible that it is a FrankenCat. I’m not sure how muck the chain cases changed over the years in the 743 models but it is possible. If it is a FrankenCat, the chain case could also come from a 600 series since the only difference between the 700 and 600 were the axle sizes. Someone may have also just swapped the drive motors out.

Just make sure that you are using the proper serial number when ordering parts. Sometimes the parts catalog will have more than one schematic in a series of serial numbers for the same part.

You may want to contact a hydraulic shop to see if they can find the proper seals.

 

[bobby blaize]

It is possible that it is a FrankenCat. I'm not sure how muck the chain cases changed over the years in the 743 models but it is possible. If it is a FrankenCat, the chain case could also come from a 600 series since the only difference between the 700 and 600 were the axle sizes. Someone may have also just swapped the drive motors out.

Just make sure that you are using the proper serial number when ordering parts. Sometimes the parts catalog will have more than one schematic in a series of serial numbers for the same part.

You may want to contact a hydraulic shop to see if they can find the proper seals.

I will see if the new seals I ordered fit. If they work I will post the part numbers here for future reference. I may have a pressure issue causing the chain case to fill up from overflow circuit. I cleaned the stone filter, but not the relief valves because I couldn't get them out. I will work on that while I wait for seals. I will have to open the case panel and observe when I fire it up next. It was filling up fast so I should be able to see where it is coming from while it's running.

 

[bobby blaize]

This is the motor housing where the seal goes. The brass seal is what was pulled out. The larger seal is what is shown in the manual and what it called for when I ordered the part for the 743. It must have been changed to the larger size over time and my chain case is older, I don't know.

Either way the new seal is a dual seal except it only has a spring around one side of the seal so one side is just a dust seal I guess. The seal I pulled out was apparently in backwards because the spring side was facing into the chain case. I think that may be why oil was going past the seal into the chain case. Unfortunately I put the new seal in the same way before I realized it was wrong. I am planning on flipping the seal around when I install the new seal again. After that I will start it up and see if oil is coming into the chain case while it's running. I will change the other side out when I get another seal.

The universal seal I ordered was Oil Shaft Seal 2-1/2" x 3-3/4" x 3/8" Double Lip TC .

 

[bobby blaize]

I made this video showing the new seal installation. I removed one seal and installed the dual seal backwards before I realized the existing seal was backwards. This video shows the correct installation. I left the other side the way it was to test if the dual seal could work either way and if it leaks into the chain case I will remove and replace it later.

Tell me if there is anything obviously wrong with what I did or said so I don't spread bad info.

 

[psmith1960]

Thanks.

It is the access plate. I will pull the motors and replace the shaft seals. Thanks for the info. I found another thread with the seal
part number (#6705847).

I only had one of the motors off and put o-rings in it that were missing. The previous owner didn't know anything about bobcats and put everything together wrong or without the seals. I should have known that the only piece I didn't pull apart would also be put together wrong since apparently they had the entire bobcat apart.

I am working on a 743 also . I think it has the same drive motor as yours . Do you have a seal kit number for the drive motor ? I would like to find a video of rebuilding this style drive motor. Any suggestions on doing this rebuild we be great.

 

[brdgbldr]

I am working on a 743 also . I think it has the same drive motor as yours . Do you have a seal kit number for the drive motor ? I would like to find a video of rebuilding this style drive motor. Any suggestions on doing this rebuild we be great.

Here is a link to the parts catalog:
https://partscatalog.bobcat.com/

You may be able to find the Bobcat part numbers and then cross reference them on the internet.

 

[psmith1960]

You said you replace some o-rings in the motor . Tell me how you got everything back together ?