'89 Bobcat 743 control valve

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billrbg

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This is the one that controls the (front) bucket lift and tilt. It is located just to the right of the engine flywheel, below the fuel tank. It is leaking on the rear side, probably from the spool covers, but I haven't got in there enough yet to be sure. What I am hearing is that valve is very difficult to work on in there, I will need a variety swivels, extenders, crow-foots, luck, and cussing! Does anyone have a good diagram of that valve's construction, like an IPB or cut-away, so that I can be best prepared as I fumble around in there to remove the spool covers and spools?
 

SkidRoe

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OM will have a manual that will help, just make sure your profile contains your e-mail address. That said, getting the control out is the worst part of the job. The control it self is pretty easy to change out the spool seals; nothing is going to fly out when you take the rear cover off. Make sure you have your serial number handy when you order the replacement seals. Good luck!!
 
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billrbg

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OM will have a manual that will help, just make sure your profile contains your e-mail address. That said, getting the control out is the worst part of the job. The control it self is pretty easy to change out the spool seals; nothing is going to fly out when you take the rear cover off. Make sure you have your serial number handy when you order the replacement seals. Good luck!!
The local Bobcat dealer/servicer says the spools can be removed with the valve in place. What's your opinion on that, as opposed to removing the valve? Right now it leaks a quart or so per hour, but every time I look at how difficult it is to get in there I just go buy more fluid... The concern there is that I, or somebody else, will forget to add fluid often enough and the pumps or motors will get damaged. Are you sure you can't tell me that it just looks like a difficult job, but is really easy once the battery is out?
 

SkidRoe

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The local Bobcat dealer/servicer says the spools can be removed with the valve in place. What's your opinion on that, as opposed to removing the valve? Right now it leaks a quart or so per hour, but every time I look at how difficult it is to get in there I just go buy more fluid... The concern there is that I, or somebody else, will forget to add fluid often enough and the pumps or motors will get damaged. Are you sure you can't tell me that it just looks like a difficult job, but is really easy once the battery is out?
The other concern is over time the leak is only get worse, not better. I will let someone who has a 743 weigh in on the difficulty of pulling the control valve. It sounds like you only have one spool leaking right now, but I would change the seals on all of them while I was at it.
I have had the control out of mine when I added the auxiliary hydraulic spool. It looked like a daunting task when I started it, but it was not too bad. These valves are definitely easier to work on when they are sitting on the bench.
FWIW - SR
 

OldMachinist

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The other concern is over time the leak is only get worse, not better. I will let someone who has a 743 weigh in on the difficulty of pulling the control valve. It sounds like you only have one spool leaking right now, but I would change the seals on all of them while I was at it.
I have had the control out of mine when I added the auxiliary hydraulic spool. It looked like a daunting task when I started it, but it was not too bad. These valves are definitely easier to work on when they are sitting on the bench.
FWIW - SR
There were several different control valves used on the 743 depending on the serial number. Please post the serial number so we know which valve you have.
Always remember that all Bobcat parts and service manuals are serial number driven, There are no model years like automobiles.
 
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billrbg

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There were several different control valves used on the 743 depending on the serial number. Please post the serial number so we know which valve you have.
Always remember that all Bobcat parts and service manuals are serial number driven, There are no model years like automobiles.
I'll get and post the S/N, probably not until tomorrow.
 

Tazza

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I'll get and post the S/N, probably not until tomorrow.
If it's the more modern style that is cast as one piece, it isn't too hard to work on.
Drain all the oil you can, as it will all want to pour out when the spools are removed.
Remove the linkage at the front, remove the allen screws that hold the boot on, remove the rear cap and circlip (if fitted). Slide the front boot and the rear cap. If it had the circlip, carefully slide it off holding your hand around it as there is a spring and two balls that will want to fly out.
With the cap off, slide the spool out the back. If there are any lines in the way, bend them back, no NOT put any side load on the spool or it may bend and it will be stuffed. It takes a lot of pressure to bend, just don't push it.
With the spool out, use a pick and remove teh quad ring, one front one back. Oil it up and slide the spool back in, i found twisting it around helped get it back in.
That is a very basic run down, hopefully you can work with that.
 
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billrbg

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If it's the more modern style that is cast as one piece, it isn't too hard to work on.
Drain all the oil you can, as it will all want to pour out when the spools are removed.
Remove the linkage at the front, remove the allen screws that hold the boot on, remove the rear cap and circlip (if fitted). Slide the front boot and the rear cap. If it had the circlip, carefully slide it off holding your hand around it as there is a spring and two balls that will want to fly out.
With the cap off, slide the spool out the back. If there are any lines in the way, bend them back, no NOT put any side load on the spool or it may bend and it will be stuffed. It takes a lot of pressure to bend, just don't push it.
With the spool out, use a pick and remove teh quad ring, one front one back. Oil it up and slide the spool back in, i found twisting it around helped get it back in.
That is a very basic run down, hopefully you can work with that.
Serial number is 501948717 Any suggestions on a convenient place to drain the hydraulic fluid? I can see the spool covers on the rear, but can't see the linkage on the front. That is going to have to be all by feel or mirrors, correct? Or is there better access from above if the fuel tank is removed???
 

antfarmer2

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Serial number is 501948717 Any suggestions on a convenient place to drain the hydraulic fluid? I can see the spool covers on the rear, but can't see the linkage on the front. That is going to have to be all by feel or mirrors, correct? Or is there better access from above if the fuel tank is removed???
Just take off the four nuts off the cage and flip it up make sure you tie it back good can hurt you bad and check to the left side of the seat some have two plugs there you need to unhook first
 

antfarmer2

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Just take off the four nuts off the cage and flip it up make sure you tie it back good can hurt you bad and check to the left side of the seat some have two plugs there you need to unhook first
A good time to replace fuel lines clean the fuel tank and replace fuel pick up line
 

Tazza

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A good time to replace fuel lines clean the fuel tank and replace fuel pick up line
The way i drain fluid others do not always agree, so do as you wish.
I rin the machine at idle and pump the oil out the front aux lines till it starts spitting, shut down then do the work and re-fill.
 
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billrbg

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The way i drain fluid others do not always agree, so do as you wish.
I rin the machine at idle and pump the oil out the front aux lines till it starts spitting, shut down then do the work and re-fill.
I understand why that draining method may be "controversial", but it appeals to me! This job looks miserable enough to do, without making the draining a messy chore. Now that I have posted the S/N, can I be expecting a diagram of how that valve is constructed?
 

OldMachinist

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I understand why that draining method may be "controversial", but it appeals to me! This job looks miserable enough to do, without making the draining a messy chore. Now that I have posted the S/N, can I be expecting a diagram of how that valve is constructed?
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I have the part of the service manual that deals with working on the valve also but it's a pdf file and there's isn't a way on this forum to upload files so I would need a email address to send it to.
 
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billrbg

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I have the part of the service manual that deals with working on the valve also but it's a pdf file and there's isn't a way on this forum to upload files so I would need a email address to send it to.
I will appreciate anything you can send to: Any chance that exploded-view and parts list can be sent as .pdf? That will make it easier for me to study it.
 
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billrbg

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I will appreciate anything you can send to: Any chance that exploded-view and parts list can be sent as .pdf? That will make it easier for me to study it.
Hmm... my email address was deleted when the post was put up! It is my user name here (billrbg) @yahoo.com
 
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billrbg

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Hmm... my email address was deleted when the post was put up! It is my user name here (billrbg) @yahoo.com
I am very grateful to "OldMachinist" for the info sent to me. I have just glanced through it, but it seems to be every thing I could ask for. I think now my only obstacle is getting contorted enough to get in there! Stay tuned in... I'll post again, to closed this out with a cry of "Success!", if nothing else.
 
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billrbg

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I am very grateful to "OldMachinist" for the info sent to me. I have just glanced through it, but it seems to be every thing I could ask for. I think now my only obstacle is getting contorted enough to get in there! Stay tuned in... I'll post again, to closed this out with a cry of "Success!", if nothing else.
I spent some "quality time" with this beast today and have reluctantly concluded that I will leave it alone until it leaks much worse. Reaching it from the front means removing several big hoses to the pumps and port block; and after that still not easy. Right now I can only see 5 of the 8 lines that must be going to that control valve. Reaching from the rear, to do the seals with the valve still in-place, would mean doing everything regarding the seals, springs, detents, etc. with some kind of tweezers or tongs. And that would be after removing the alternator, coolant reservoir, battery, and coolant hoses. That valve is just too far forward for me to reach, even doing it blind without trying to get my head positioned to see. Maybe removing the engine mounting screws so that it could be shoved to the left would help... but I doubt it. My thanks, again, to all that tried to help. I hope you don't regret wasting your time on this dead-end thread. Hey, maybe I'll get *lucky* and the engine will die so it has to come out anyway; then doing this valve will be easy!
 

antfarmer2

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I spent some "quality time" with this beast today and have reluctantly concluded that I will leave it alone until it leaks much worse. Reaching it from the front means removing several big hoses to the pumps and port block; and after that still not easy. Right now I can only see 5 of the 8 lines that must be going to that control valve. Reaching from the rear, to do the seals with the valve still in-place, would mean doing everything regarding the seals, springs, detents, etc. with some kind of tweezers or tongs. And that would be after removing the alternator, coolant reservoir, battery, and coolant hoses. That valve is just too far forward for me to reach, even doing it blind without trying to get my head positioned to see. Maybe removing the engine mounting screws so that it could be shoved to the left would help... but I doubt it. My thanks, again, to all that tried to help. I hope you don't regret wasting your time on this dead-end thread. Hey, maybe I'll get *lucky* and the engine will die so it has to come out anyway; then doing this valve will be easy!
The engine comes out quick and easy and always good to check the ujoints if they go can do alot of damage
 
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billrbg

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The engine comes out quick and easy and always good to check the ujoints if they go can do alot of damage
Are you saying the engine decouples from the pump unit, so the pumps and all that can stay in place? If so, I'm guessing that would be at one of those U-joints, but I don't recall seeing one yet. How difficult are they to reach? How many hours for an experienced person to do an engine R&R? I can multiply that by whatever factor I think is suitable here! Obviously, I would like to fix this properly, but am also trying to remain practical.
 
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