Hydraulic Leak - 743

[ylsf]

I went to top up our 743 Hydraulics this afternoon and 10 minutes later noticed hydraulic fluid on the ground. Looking closer at where the oil was coming from it was coming out of the black compartment on the left hand side of the machine (looking from the front). Based on what I have read and youtube videos I have seen so far it looks like that is where the hydraulic controls are. I haven't lifted the cab yet because I figured I wanted to read up on what to look out for first. The machine was not run today at all. I am wondering what the black compartment is for? If it best to go from above or is there a way to remove that black compartment. I noticed the seals around the compartment are in bad shape. I could feel the hydraulic oil on the one area where the seals are pretty shot. I am attaching a picture of what I am referring to. I requested in another thread the service manual for the machine. We also have a s220 and use that machine for most work but I have used the 743 back in January and it was lifting up/down okay but a little slower than usual. https://www.dropbox.com/s/240kd4girbxdpmq/2013-02-13%2015.24.34.jpg?m

 

[ylsf]

Sorry, wrong link for the photo, don't see a way to edit the original pic: https://www.dropbox.com/s/240kd4girbxdpmq/2013-02-13%2015.24.34.jpg

 

[ylsf]

Sorry, wrong link for the photo, don't see a way to edit the original post: https://www.dropbox.com/s/240kd4girbxdpmq/2013-02-13%2015.24.34.jpg

 

[Ken743B]

Sorry, wrong link for the photo, don't see a way to edit the original post: https://www.dropbox.com/s/240kd4girbxdpmq/2013-02-13%2015.24.34.jpg

That's the hydrostatic drive motor access cover.

 

[Tazza]

That's the hydrostatic drive motor access cover.

A leak there could be a few things.
How often do you have to top off your oil? your drive motors may be leaking into the chain case and its coming out of the inspection cover. With the machine on flat ground, remove the plug at the front, the oil should be level with the threads on the plug.
It could be a bad hose to the drive motor, bad or cracked case drain hose (the little one from the motor)
It could also be the seals on the hydrostatic pump where the steering linkages connect to.

 

[ylsf]

A leak there could be a few things.
How often do you have to top off your oil? your drive motors may be leaking into the chain case and its coming out of the inspection cover. With the machine on flat ground, remove the plug at the front, the oil should be level with the threads on the plug.
It could be a bad hose to the drive motor, bad or cracked case drain hose (the little one from the motor)
It could also be the seals on the hydrostatic pump where the steering linkages connect to.

Thanks for the responses so far. We only have used the bobcat once this year (i.e. in the last 12 months) and it is currently being stored inside. We use the s220 as our primary machine and the 743 is at another location. I think there was a leak before but at the time I had thought it was the engine oil. It didn't leak after moving it last time so I didn't think much of it. It was after filling up the hyraulic that I noticed the oil on the ground. I will open up the inspection cover and see what I can see there and take a look for the plug as well. This is a good start, thanks!

 

[Tazza]

Thanks for the responses so far. We only have used the bobcat once this year (i.e. in the last 12 months) and it is currently being stored inside. We use the s220 as our primary machine and the 743 is at another location. I think there was a leak before but at the time I had thought it was the engine oil. It didn't leak after moving it last time so I didn't think much of it. It was after filling up the hyraulic that I noticed the oil on the ground. I will open up the inspection cover and see what I can see there and take a look for the plug as well. This is a good start, thanks!

Don't touch the cover, just remove the plug at the front, see if the oil level is high. No need to take the cover off as you will need to re-seal it.

 

[Ken743B]

Don't touch the cover, just remove the plug at the front, see if the oil level is high. No need to take the cover off as you will need to re-seal it.

I'd all most bet that one of the hoses that go into the drive motor is leaking, at least that's been my experience when it's leaking from the drive motor cover.

 

[ylsf]

Don't touch the cover, just remove the plug at the front, see if the oil level is high. No need to take the cover off as you will need to re-seal it.

I ended up removing the cover before I saw this post... The seal was shot on it (like, the rubber part was all mangled up already and kind of hanging down in parts). Figured I would replace that seal anyway. The cover was encased with like 4" of gunk (oils/debris/etc). I tried opening up the plug at the front but was wondering if it is "sealed" thread or just a normal thread because it wasn't coming off. I didn't want to apply to much pressure to it in fear of damaging something. However, if it is a normal thread I will apply more pressure to it and try to remove the plug. I flipped up the cab and didn't notice anything off hand. Do the 743 have a little float pebble as well normally in the hydraulic indicator? I don't see an indicator.

 

[ylsf]

I ended up removing the cover before I saw this post... The seal was shot on it (like, the rubber part was all mangled up already and kind of hanging down in parts). Figured I would replace that seal anyway. The cover was encased with like 4" of gunk (oils/debris/etc). I tried opening up the plug at the front but was wondering if it is "sealed" thread or just a normal thread because it wasn't coming off. I didn't want to apply to much pressure to it in fear of damaging something. However, if it is a normal thread I will apply more pressure to it and try to remove the plug. I flipped up the cab and didn't notice anything off hand. Do the 743 have a little float pebble as well normally in the hydraulic indicator? I don't see an indicator.

Ok, I tried to remove the plug again with a 1 1/8" socket and it wouldn't come out. I think I ended up stripping a bit of the edge of the socket (only had a 1 1/8" that had the multiple points of contact vs. just a 5 point sides or however you call it). Need to look around the shop to see if we have a large socket without the multi point to try to remove it. Anyway, last night I left a few peices of paper towel under various valves to see if I could trace back where it is leaking from. It appears that it is leaking from the Hydraulic Control valve (if I understand the diagrams I have seen correctly this is the valve that would be just behind the "throttle" control of the machine. It looks like it is the 2nd connection from the top at the back. I left another two pieces of paper towel there today to see if I can verify that it is indeed that one. Do these connections have o-rings? If it gets to a point that the whole valve needs to be removed then I will call in our service guy. I am just trying to avoid having to truck the machine over to their shop and leave it there.

 

[Tazza]

Ok, I tried to remove the plug again with a 1 1/8" socket and it wouldn't come out. I think I ended up stripping a bit of the edge of the socket (only had a 1 1/8" that had the multiple points of contact vs. just a 5 point sides or however you call it). Need to look around the shop to see if we have a large socket without the multi point to try to remove it. Anyway, last night I left a few peices of paper towel under various valves to see if I could trace back where it is leaking from. It appears that it is leaking from the Hydraulic Control valve (if I understand the diagrams I have seen correctly this is the valve that would be just behind the "throttle" control of the machine. It looks like it is the 2nd connection from the top at the back. I left another two pieces of paper towel there today to see if I can verify that it is indeed that one. Do these connections have o-rings? If it gets to a point that the whole valve needs to be removed then I will call in our service guy. I am just trying to avoid having to truck the machine over to their shop and leave it there.

A single hex socket would be best, as you have found. Try hitting the head of the bolt a few times with a hammer, it sometimes helps break the seal free.
When putting the cover back on, use quality silicone, even do the bolt threads to keep the water out.
The control block can be done in the machine, it's not easy but can be done. Removing it is not a fun job at all

 

[ylsf]

A single hex socket would be best, as you have found. Try hitting the head of the bolt a few times with a hammer, it sometimes helps break the seal free.
When putting the cover back on, use quality silicone, even do the bolt threads to keep the water out.
The control block can be done in the machine, it's not easy but can be done. Removing it is not a fun job at all

Ok, it has been a while since my last post here. I was looking through my shop tools and can't find a single hex to remove the nut at the front of the machine. It seems like I have narrowed down where the leak is coming from though. It seems like it is coming from the top - see the attached picture https://www.dropbox.com/s/r7nk7pawklfw4v3/Leak1.jpg https://www.dropbox.com/s/5t2voubxzaj8hwb/Leak2.jpg I have wiped down these spots more than once and found that oil regathers at these points. I have not even moved the machine in the meantime (nor started it). I would prefer not to have to buy a new single hex if it can be avoided to check the level on the front(I imagine for that size they aren't cheap). If the machine is over filled would it exhibit these happening? I opened the lid on the hydraulic tank and removed the filter screen. It seems that the hydraulic is less than half way up the tank.

 

[Tazza]

Ok, it has been a while since my last post here. I was looking through my shop tools and can't find a single hex to remove the nut at the front of the machine. It seems like I have narrowed down where the leak is coming from though. It seems like it is coming from the top - see the attached picture https://www.dropbox.com/s/r7nk7pawklfw4v3/Leak1.jpg https://www.dropbox.com/s/5t2voubxzaj8hwb/Leak2.jpg I have wiped down these spots more than once and found that oil regathers at these points. I have not even moved the machine in the meantime (nor started it). I would prefer not to have to buy a new single hex if it can be avoided to check the level on the front(I imagine for that size they aren't cheap). If the machine is over filled would it exhibit these happening? I opened the lid on the hydraulic tank and removed the filter screen. It seems that the hydraulic is less than half way up the tank.

That hose is held on with hose clamps, may be worth a shot to tighten them up a little.
It's still not a bad idea to try and get a socket to remove the plug, then you know the level is right. The good thing is, i believe it and the wheel nuts are 1”, so the socket won't be used for only one job.