Bobcat 743 lift arm drift

[Tazza]

I personally didn't take anyone for rude. I wholeheartedly agree that diagnosing is the smart thing to do. That being said....I ordered the seal kit for the control valve (there must be some percentage of being right!) . I noticed that the diagram doesn't show any detent balls. I'm thinking the lift and aux spools should both have them, though. The kit is $65. I kind of wish I had the component repair manual. Oh well, what's the worst that could happen?

My manual doesn't show how to repair it as such, but it shows an exploded diagram. Just do one section at a time and you have 3 others to compair it with. They are alot easier than they seem. I have attached another picture outlining the load checks, the detent balls, and the quad rings on the spools you MUST replace if your in there fiddling. Make sure you replace the rubber boots that protect the end of the spool from dirt.
If you have the old style plastic boots, you will not require the bronze spacers that they use. The new ones just push in and the bronze spacer is no longer needed.
I hope this helps clear things up a bit.

 

[roadkill]

My manual doesn't show how to repair it as such, but it shows an exploded diagram. Just do one section at a time and you have 3 others to compair it with. They are alot easier than they seem. I have attached another picture outlining the load checks, the detent balls, and the quad rings on the spools you MUST replace if your in there fiddling. Make sure you replace the rubber boots that protect the end of the spool from dirt.
If you have the old style plastic boots, you will not require the bronze spacers that they use. The new ones just push in and the bronze spacer is no longer needed.
I hope this helps clear things up a bit.

Thanks Tazza, that's perfect. You sure go above and beyond the call. I ordered the seats and balls, and springs for each. I do have the parts manual to go by to re-assemble the thing. The service manual makes it sound fairly easy to get the port block and control valve out. I'll post how it went next week, or beg for help, one or the other

!

 

[Tazza]

Thanks Tazza, that's perfect. You sure go above and beyond the call. I ordered the seats and balls, and springs for each. I do have the parts manual to go by to re-assemble the thing. The service manual makes it sound fairly easy to get the port block and control valve out. I'll post how it went next week, or beg for help, one or the other!

Not a problem, as for removing the control block, this is not an easy job, i wish you the bet of luck, just take your time and be patient. Any problems just yell!

 

[roadkill]

Not a problem, as for removing the control block, this is not an easy job, i wish you the bet of luck, just take your time and be patient. Any problems just yell!

Tazza, HELP! I can't get the third connection down on the back row of the control valve off. I have the front row off, including the fittings. On the back I got the top two flare nuts off. I loosened the nut on the third one down, but it's not a slip joint like I thought. It backed out a way then tightened. It has an elbow. I can get a big 1" wrench onto the flare nut around the elbow, but don't have room to move it.
After that, all that's left is the one connection under and the "million dollar" hose on the bottom. I can't get the solid tube loosened that goes over the valve and into the back. It's connected to the "million dollar" hose at a tee. It looks like I can leave the last hose connected to the valve and slide the valve and hose out the front (if I can get that solid tube disconnected. It goes to an elbow back in the engine compartment.) I bet I'm gonna have to take the engine out, aren't I? I hope not. Any insight you can give would be appreciated. I don't have the money to take it to a dealer.

 

[Luthor]

Tazza, HELP! I can't get the third connection down on the back row of the control valve off. I have the front row off, including the fittings. On the back I got the top two flare nuts off. I loosened the nut on the third one down, but it's not a slip joint like I thought. It backed out a way then tightened. It has an elbow. I can get a big 1" wrench onto the flare nut around the elbow, but don't have room to move it.
After that, all that's left is the one connection under and the "million dollar" hose on the bottom. I can't get the solid tube loosened that goes over the valve and into the back. It's connected to the "million dollar" hose at a tee. It looks like I can leave the last hose connected to the valve and slide the valve and hose out the front (if I can get that solid tube disconnected. It goes to an elbow back in the engine compartment.) I bet I'm gonna have to take the engine out, aren't I? I hope not. Any insight you can give would be appreciated. I don't have the money to take it to a dealer.

Roadkill, have a look at my post dated 15 Nov. 2005 for details of how I got access to the Hydraulic Control Valve. Good luck.

 

[roadkill]

Roadkill, have a look at my post dated 15 Nov. 2005 for details of how I got access to the Hydraulic Control Valve. Good luck.

Luthor, Man you ripped that thing apart. The dealer had the engine out and replaced that hose. They are new....after they put the engine back in they had the aux hyd's locked in and couldn't figure out what was wrong with the pump (nothing!). They would have noticed the lift arms lowering. I suppose it would have been too late by then anyway. It looks like you took out the steering arms and links and the front metal plate that the arms go through, too. I also see you left that elbow on the valve. I take it it doesn't come out? So which is better, the engine or the pump?

 

[Tazza]

Luthor, Man you ripped that thing apart. The dealer had the engine out and replaced that hose. They are new....after they put the engine back in they had the aux hyd's locked in and couldn't figure out what was wrong with the pump (nothing!). They would have noticed the lift arms lowering. I suppose it would have been too late by then anyway. It looks like you took out the steering arms and links and the front metal plate that the arms go through, too. I also see you left that elbow on the valve. I take it it doesn't come out? So which is better, the engine or the pump?

I think it would be alot easier if you pulled the engine, seriously its not that hard to remove/replace. I have never tried to remove the control block with the tube lines still in the machine, when i did it i was removing EVERYTHING so it made it so easy. You really need a 1" flare nut spanner to make it easier, i just used shifters and open end spanners, but i could remove complete tube lines to gain access.
If you have a few friends that can give you some help, i would pull the engine. Just un-do the 4 mounting bolts, exhaust, coolant hoses and any wiring and fuel. Use a small crow bar to juggle the engine back. Get 2 old milk crates and a sheet of steel or wood to make like a table behind the machine. Lift and drag the engine out on to the make shift table. If you had a small hoist it is very easy, just use it to take up the slack and use the bar to move the engine back and on to the bench.
If you pull the engine, make sure you check your universal joints!!! and grease them up good. If these lock up, they can damage your pump.
With that said, you may still be able to do it without pulling the engine, but it will be horrible!
That hose you mention, thats the return hose i think, i think i left it attached to the control block, as you can't get to the nut.
Sorry i can't be of more help :/ just be patient with it, you will get it out.

 

[roadkill]

I think it would be alot easier if you pulled the engine, seriously its not that hard to remove/replace. I have never tried to remove the control block with the tube lines still in the machine, when i did it i was removing EVERYTHING so it made it so easy. You really need a 1" flare nut spanner to make it easier, i just used shifters and open end spanners, but i could remove complete tube lines to gain access.
If you have a few friends that can give you some help, i would pull the engine. Just un-do the 4 mounting bolts, exhaust, coolant hoses and any wiring and fuel. Use a small crow bar to juggle the engine back. Get 2 old milk crates and a sheet of steel or wood to make like a table behind the machine. Lift and drag the engine out on to the make shift table. If you had a small hoist it is very easy, just use it to take up the slack and use the bar to move the engine back and on to the bench.
If you pull the engine, make sure you check your universal joints!!! and grease them up good. If these lock up, they can damage your pump.
With that said, you may still be able to do it without pulling the engine, but it will be horrible!
That hose you mention, thats the return hose i think, i think i left it attached to the control block, as you can't get to the nut.
Sorry i can't be of more help :/ just be patient with it, you will get it out.

Is that elbow that is third down on the back removable? If that would slide out I think I'd be home free. The pump looks like it would just be four bolts, five hoses and the u-joint to the engine. Oh, I forgot about the steering mechanisms! I haven't looked at the service manual yet. My stupid job is keeping me from working on the Bobcat

!

 

[Tazza]

Is that elbow that is third down on the back removable? If that would slide out I think I'd be home free. The pump looks like it would just be four bolts, five hoses and the u-joint to the engine. Oh, I forgot about the steering mechanisms! I haven't looked at the service manual yet. My stupid job is keeping me from working on the Bobcat !

ALL the fittings on the control block can be removed. The hardest part is you may need to remove the fitting above ansd below to be able to get it to spin.

 

[roadkill]

ALL the fittings on the control block can be removed. The hardest part is you may need to remove the fitting above ansd below to be able to get it to spin.

Well Boys, I did it. I'd better specify, I got the control valve OUT. Part #27 on the above diagram, a relief valve was missing the little o-ring, and the little washer was torn. Those detent balls are a pain, and that's on the bench. I don't think I could have got them reaching in past the engine. My Dad was helping me. Now to try to get the valve back IN

!
The flare nut third down on the back with the elbow was a pain. I had just enough room with the big wrench to just move the nut. Then I used a stubby 1" and the handle of a sledge hammer to break it the rest of the way. I loosened the lock nut and took out the elbow, and the whole valve with the lower short hose came out the front. I should take some pictures. My Dad really didn't want to take the engine or pump out.
My Dad had to take off so I haven't even tried to put the valve back in. There sure were a lot of seals left in the package. A bunch with slots on one side. I read that the same kits are used for multiple machines, but there are ALOT of seals and O-rings left.
I'll post back how the re-install goes.

 

[Tazza]

Well Boys, I did it. I'd better specify, I got the control valve OUT. Part #27 on the above diagram, a relief valve was missing the little o-ring, and the little washer was torn. Those detent balls are a pain, and that's on the bench. I don't think I could have got them reaching in past the engine. My Dad was helping me. Now to try to get the valve back IN !
The flare nut third down on the back with the elbow was a pain. I had just enough room with the big wrench to just move the nut. Then I used a stubby 1" and the handle of a sledge hammer to break it the rest of the way. I loosened the lock nut and took out the elbow, and the whole valve with the lower short hose came out the front. I should take some pictures. My Dad really didn't want to take the engine or pump out.
My Dad had to take off so I haven't even tried to put the valve back in. There sure were a lot of seals left in the package. A bunch with slots on one side. I read that the same kits are used for multiple machines, but there are ALOT of seals and O-rings left.
I'll post back how the re-install goes.

Well done!
Just make sure you replace any O rings on the fittings you removed. Use oil or grease when re-fitting them. Other than that, just go steady and try to replace them in the reverse order you took them off.

 

[roadkill]

Well done!
Just make sure you replace any O rings on the fittings you removed. Use oil or grease when re-fitting them. Other than that, just go steady and try to replace them in the reverse order you took them off.

I meant to point out that I got the valve out with the engine and pump in the machine. It wasn't easy and I'm not positive I'll be able to get the valve back in that way.....I should be able to, but some of the fittings on the side of the valve were pinched inbetween the tubelines and the valve body, not to mention that connection after the elbow. I should tear the beast down like Tazza! Tazza, what are those seals with the slot in the side for? Thanks for all the help.

 

[Tazza]

I meant to point out that I got the valve out with the engine and pump in the machine. It wasn't easy and I'm not positive I'll be able to get the valve back in that way.....I should be able to, but some of the fittings on the side of the valve were pinched inbetween the tubelines and the valve body, not to mention that connection after the elbow. I should tear the beast down like Tazza! Tazza, what are those seals with the slot in the side for? Thanks for all the help.

I don't know what you mean, if you could post a pic i may be able to help a bit better. I don't remember any seals with a slot in the side of them.
One note.. The control block, the 2 quad rings that fit on either end f the spool, make sure the side with the indentation faces towards the centre of the block. This is called the *pressure side* if you don't have them around the rite way they will not seal as they should!

 

[roadkill]

I don't know what you mean, if you could post a pic i may be able to help a bit better. I don't remember any seals with a slot in the side of them.
One note.. The control block, the 2 quad rings that fit on either end f the spool, make sure the side with the indentation faces towards the centre of the block. This is called the *pressure side* if you don't have them around the rite way they will not seal as they should!

I don't have a host to post pics, I could email a couple. The seals from the ends of the spools were black and had indentations on both sides, and inner and outer. The indents seemed the same on both sides. The orange seals in the package that I didn't use have indentations (what I called slots) on only one side, and a lip on that side. There are also blue-green seals that have indents on two sides and a lip. I took pictures that I can send. I put the valve back together with the symmetrical seals like the ones that came out, but I couldn't tell any difference in the depth of the indentations. Now I'm nervous.

 

[roadkill]

I don't have a host to post pics, I could email a couple. The seals from the ends of the spools were black and had indentations on both sides, and inner and outer. The indents seemed the same on both sides. The orange seals in the package that I didn't use have indentations (what I called slots) on only one side, and a lip on that side. There are also blue-green seals that have indents on two sides and a lip. I took pictures that I can send. I put the valve back together with the symmetrical seals like the ones that came out, but I couldn't tell any difference in the depth of the indentations. Now I'm nervous.

I figured out the picture thing, I think. The first one is one side of the rings and the second is the reverse side of all three.
Side 1:

Side 2:

The parts manual says to refer to a "serviceletter 31AUG 92". The old seals weren't leaking. Anyone know what the serviceletter says? Can the black seals be put in incorrectly? I sure wouldn't want to have to remove the valve again

!

 

[Tazza]

I figured out the picture thing, I think. The first one is one side of the rings and the second is the reverse side of all three.
Side 1:

Side 2:

The parts manual says to refer to a "serviceletter 31AUG 92". The old seals weren't leaking. Anyone know what the serviceletter says? Can the black seals be put in incorrectly? I sure wouldn't want to have to remove the valve again !

The other 2 O rings lok like pressure seals from a ram.
If you installed the same looking quad rings you took out, im sure you will be fine.
Anyone else done this before?

 

[roadkill]

The other 2 O rings lok like pressure seals from a ram.
If you installed the same looking quad rings you took out, im sure you will be fine.
Anyone else done this before?

Were your seals the same? Black and symmetrical?

 

[Tazza]

Were your seals the same? Black and symmetrical?

I think they were, but it was a few months back now. The seals i got were not genuine from bobcat, they cost me about $5 for a complete set. From memory, the quad rings were double sided, so it doesn't matter which way they are installed.

 

[roadkill]

I think they were, but it was a few months back now. The seals i got were not genuine from bobcat, they cost me about $5 for a complete set. From memory, the quad rings were double sided, so it doesn't matter which way they are installed.

I got it all back together. Some idiot forgot to tighten one end of a hose

, but I could reach it without disassembling anything, just a little mess. It still settles minorly, but you don't notice it. I left it up about a foot and shut it off just to check. It dropped about 10 inches in two hours with the engine off. It sure is nice to set a height and it doesn't drop! Now I can say that you don't HAVE to remove the engine or pump to get the Control valve out. I'd rather chew on broken glass and shove bamboo under my fingernails than to do it again, but it can be done. The load check seats, on the block side, didn't look the best, any one know if the load check seats might wear together and stop the settling, or could it be a bit of air in the system? I only used it a little after re-assembly, it was raining. There aren't any good machine shops in my area.
There's also quite a bit of play where the tilt ram attaches to the bobtach. Is this a difficult repair?
Man those new detent balls and springs make a big difference. I thought they were ok to start, but now they lock in tight.
I found a stubby 1" combo wrench, about 5 or 6" long, that came in extremely handy. I didn't have to cut one and I found myself hooking a finger in the box end all the time so it didn't slip out of my hand. Anyone trying this might want to invest in one. Mine was a chinese one for about 5 bucks. I also got a 1" flare nut wrench that I wish I had had for disassembly.

 

[Tazza]

I got it all back together. Some idiot forgot to tighten one end of a hose , but I could reach it without disassembling anything, just a little mess. It still settles minorly, but you don't notice it. I left it up about a foot and shut it off just to check. It dropped about 10 inches in two hours with the engine off. It sure is nice to set a height and it doesn't drop! Now I can say that you don't HAVE to remove the engine or pump to get the Control valve out. I'd rather chew on broken glass and shove bamboo under my fingernails than to do it again, but it can be done. The load check seats, on the block side, didn't look the best, any one know if the load check seats might wear together and stop the settling, or could it be a bit of air in the system? I only used it a little after re-assembly, it was raining. There aren't any good machine shops in my area.
There's also quite a bit of play where the tilt ram attaches to the bobtach. Is this a difficult repair?
Man those new detent balls and springs make a big difference. I thought they were ok to start, but now they lock in tight.
I found a stubby 1" combo wrench, about 5 or 6" long, that came in extremely handy. I didn't have to cut one and I found myself hooking a finger in the box end all the time so it didn't slip out of my hand. Anyone trying this might want to invest in one. Mine was a chinese one for about 5 bucks. I also got a 1" flare nut wrench that I wish I had had for disassembly.

I hate to say it, but i'm so glad it was you doing the work and not me! I did it all with engine and pumps out, it was so much easier. With that said...... i do have to jump in again to try and stop a leak in the aux. section, rite at the bottom with 2 tube lines in the way making it so i can't get the rotten spool out.
I'm not sure how the new load checks will seat in, they are hardened so i would suspect they may get a little better in time. As for air causing drift, it may cause a small amount, but i would doubt it would cause the 10" per hour you describe. I would change the tilt ram seals when you work on the bobtach pin, then you know everything is how it should be.
Air in the system will take a little while to beleed out, but it will usually just make groaning in your pumps and spongy action on your rams. Mine took quite a while to get rite, it took me about a week of starting and moving around for a few minutes then shutting down and leaving it for a few hrs. Mind you, my ENTIRE system was empty, tube lines, pumps, rams, the lot! Yours was just the spool and attached lines
Now the bobtach pin, do you have access to an oxy cutting setup, lathe and welder? if so you can do it. You said there is alot of play, your best bet is to remove the 2 bosses that hold the pin and make and weld 2 new ones in (or you could buy ones from bobcat). Just make sure you locate the bosses correctly and push the pin through so you know its tracking straight before welding. Replace the bushing inside the end of the cylinder where the pin goes through, and your pretty well set!
You only need to replace the old bosses if they are worn, if they are ok, you can just replace the pin and bush inthe end of the ram.
One modification i did to mine was to drill only 1 side of the boss and drill and tap a matching hole in one end of my pin. Unlike bobcat's one, they drill right through, but there is no way to stop the pin from twisting slightly causing wear. My way you tighten the bolt and it locks the pin so it will never move and wear (i can post a pic to make things clear). Its up to you if you go this way or not, i just felt it was better
If you need any more info just give me a yell.
OOH the hose that wasn't tight, don't feel alone there, i have done it too. I was fiddling with a hydrostatic motor and removed a hose and needed to tilt the bucket a bit so i started it and tilted it a tad. Ran for maybee 10 seconds and had a massive pool of oil on the floor!!!