Auxiliary hydraulics

[therick]

I have a 1990 743 Bobcat Skidsteer. The auxiliary hydraulic system has never been used or the bolt to use them removed. Is there any thing I should look out for, pre removal of bolt and use, or maintenance to be done before pulling the handle?

 

[brdgbldr]

I’ve never come across this before.
My one concern would be the oil in the lines. Since it never got circulated it could be very dirty. You might want to hook up a hose to each auxiliary and purge that old oil.

Hopefully the valve hasn’t froze up.

Also, the quick couplers could be rusted up. You may want to have a couple of replacement couplers just in case.

 

[therick]

I’ve never come across this before.
My one concern would be the oil in the lines. Since it never got circulated it could be very dirty. You might want to hook up a hose to each auxiliary and purge that old oil.

Hopefully the valve hasn’t froze up.

Also, the quick couplers could be rusted up. You may want to have a couple of replacement couplers just in case.

I have bought new couplers already but haven’t installed them yet, (flat face modern ones). I have pushed in the coupler centers on the current ones to release oil to see if it was there and oil did release and valve closed. I have read an older post where a guy borrowed one like mine and the valve stuck open because of rust on the backside. And that’s why I’m hesitant to use it. It sounded like a major repair. Purging the hydraulic oil is a good idea. Would you know if there is access to the backside of the valve so I can inspect and or clean up rust if there is some?

 

[brdgbldr]

Not sure which specific 743 you have.
Go to this website:
https://www.bobcatpartsonline.com/#/catalogBrowserEnter in your serial number and then search “auxiliary”. This will bring up the exploded views of all parts of the auxiliary components.

This will give you an idea of what you may or may not want to look at depending on how much you want to dig into the machine. Hopefully debris that you miss the filters will take care of. You may also want to think about changing out, or at least removing and inspecting, all filters after opening up the auxiliary and running for a while just as a precaution.

 

[therick]

Not sure which specific 743 you have.
Go to this website:
https://www.bobcatpartsonline.com/#/catalogBrowserEnter in your serial number and then search “auxiliary”. This will bring up the exploded views of all parts of the auxiliary components.

This will give you an idea of what you may or may not want to look at depending on how much you want to dig into the machine. Hopefully debris that you miss the filters will take care of. You may also want to think about changing out, or at least removing and inspecting, all filters after opening up the auxiliary and running for a while just as a precaution.

Thank you

 

[koko]

I’ve never come across this before.
My one concern would be the oil in the lines. Since it never got circulated it could be very dirty. You might want to hook up a hose to each auxiliary and purge that old oil.

Hopefully the valve hasn’t froze up.

Also, the quick couplers could be rusted up. You may want to have a couple of replacement couplers just in case.

I'm going to ask this question....how could the oil in un used lines get dirty?

 

[brdgbldr]

The oil is basically stagnant in the auxiliary lines since it has not circulated for about 30 years. When the hydraulic oil is changed in a machine there is no way to get the oil out of the lines, pumps and cylinders unless you remove them or open them up. Even if the oil technically isn’t “dirty”, it could have collected moisture and is way past it’s usable, and shelf, life.

The oil in the used parts of the machine circulate, to a point, when the cylinders move back and forth and when the relief valves activate. The motors do circulate oil when operated.

Some mechanics actually use the auxiliaries to remove the old oil for maintenance since you can get more oil out of the machine this way ( let’s not start arguments weather this method is right or wrong ). In this case the auxiliary lockout bolt was still in place so the oil in those lines is going to be very old.

 

[therick]

The oil is basically stagnant in the auxiliary lines since it has not circulated for about 30 years. When the hydraulic oil is changed in a machine there is no way to get the oil out of the lines, pumps and cylinders unless you remove them or open them up. Even if the oil technically isn’t “dirty”, it could have collected moisture and is way past it’s usable, and shelf, life.

The oil in the used parts of the machine circulate, to a point, when the cylinders move back and forth and when the relief valves activate. The motors do circulate oil when operated.

Some mechanics actually use the auxiliaries to remove the old oil for maintenance since you can get more oil out of the machine this way ( let’s not start arguments weather this method is right or wrong ). In this case the auxiliary lockout bolt was still in place so the oil in those lines is going to be very old.

Thanks