Bobcat 743 Hydraulic Diagram

[avking2508]

Hello, I have a Bobcat 743 Skid Steer. It has been used hard, but has been a great machine. It developed a loud noise in hydraulics when raising and lowering the arms. I found a significant leak in large steel line just in front of battery, the large line likely a feed line, going to a T which branches out to two smaller lines. I believe the two smaller lines go to either the raise side, or lower side of the loader. Question, is there a diagram on where these lines go to? What do I have to remove to replace them? I would expect the line comes from either a pump, or control valve, but it goes under and forward. The leak seemed to be at the connection, but I think it is on the line side, but I am replacing the T anyway to make sure. Can I replace with flexible hydraulic hose? Any assistance is very much appreciated. Thank you Andrew

 

[cwjohndeere]

I use the parts diagrams on www.bobcatpartsonline.com to help me out with things like this. At the top of the page just enter your machine's serial number and it will take you to the parts catalog specific to your serial number range.

 

[7LBSSMALLIE]

common problem. the tube lines rust out . pull the eng takes about an hr. clean it out now you can see. there is like four lines just behind the plastic fan shroud. oil cooler and radiator fan shroud need to come out. if its youre first one, not that much fun.,once you get it apart you will see how it all works. inspect u joint reseal control valve, just cause youre there? replace stat input seal. sounds like a lot but its not. now you know how it works. next time easy breezy. first time not so much. and to answer question yes you can rubber line it again and again do it once do it right and be done.

 

[avking2508]

common problem. the tube lines rust out . pull the eng takes about an hr. clean it out now you can see. there is like four lines just behind the plastic fan shroud. oil cooler and radiator fan shroud need to come out. if its youre first one, not that much fun.,once you get it apart you will see how it all works. inspect u joint reseal control valve, just cause youre there? replace stat input seal. sounds like a lot but its not. now you know how it works. next time easy breezy. first time not so much. and to answer question yes you can rubber line it again and again do it once do it right and be done.

Thank you. We got it apart, and the faulty line out. No rust, but looks like the end may have a hairline crack. There is a number on the line, I think it is a part number, I will try to find out. Can you explain the following? Reseal control Valve, what do you mean? replace stat Input seal? What is this? U-Joint seems fine, like any other one. Anything specific to look for? How to put the motor back in getting the connection to the pump to line up again? Any secret to holding the end by the u-joint straight so it lines up? Again, thanks for your assistance, very helpful. Andrew

 

[Tazza]

Thank you. We got it apart, and the faulty line out. No rust, but looks like the end may have a hairline crack. There is a number on the line, I think it is a part number, I will try to find out. Can you explain the following? Reseal control Valve, what do you mean? replace stat Input seal? What is this? U-Joint seems fine, like any other one. Anything specific to look for? How to put the motor back in getting the connection to the pump to line up again? Any secret to holding the end by the u-joint straight so it lines up? Again, thanks for your assistance, very helpful. Andrew

I think he was talking about the seals on the control valve, there are seals on the spools that can leak over time. Depending on how deep you are, access may be easier now than later is all. I have done seals with the engine still in place, it's not fun, but still doable.
There is a seal on the pump behing the input shaft, if it leaks, now is the time to do it with the engine out, if it's not leaking, leave it alone, pretty easy to get to if it does later.
The code on the line should be the part number, you may even get away with welding a new fitting on the end of the line if that's where the crack is. I have brazed up rusted or worn through lines before with great results.

 

[Tazza]

I think he was talking about the seals on the control valve, there are seals on the spools that can leak over time. Depending on how deep you are, access may be easier now than later is all. I have done seals with the engine still in place, it's not fun, but still doable.
There is a seal on the pump behing the input shaft, if it leaks, now is the time to do it with the engine out, if it's not leaking, leave it alone, pretty easy to get to if it does later.
The code on the line should be the part number, you may even get away with welding a new fitting on the end of the line if that's where the crack is. I have brazed up rusted or worn through lines before with great results.

Forgot to mention the Ujount.
The way i do it is to get the engine almost in place, get a helper with a bar to nudge it forward to get the joint to engage. You have to lay down on the pump, hand through the blower housing holding the ujoint up in line with the pump shaft. Do not put a finger between the two when the motor is being moved, you don't want it squashed. When its starting to engage and if out of alignment, rotate the engine slightly and it will go in.