Bobcat 643 disconnect u-joint and buying manuals

[Tazza]

Both of you, thanks for your reply

Sterlclan - Its my theory to, but the only leak I can find is the cylinder for my bucket it dripped a little bit and a little leak with my sender, I thought I have a leak somewhere with my hydrostatic, but after I clean it up, it has been dry.

It's a little mystery, I my head there will always come oil out if the comes air in, a least at some point, but I think I will try to raise the arm a meter or so over the ground a few times, maybe with some load on, turn of the machine, and let it go down to the ground as it self, and see if there comes any oil somewhere.

Is there anyway to test a hydraulic connection, ex. If I disconnect the connection to the arms, is it possible to connect any tools and get pressure on, like if a I work on a cooling system I have a tool to connect, there can put pressure on, an I can see, if the pressure fall, the most be a leak somewhere?

Tazza - I think I will replace the clams, I have tightening them, as most I can, I believe, is the hose special or can I use a hose from a cooling system, the one on it, is very stiff and hard?
About the air getting worse – When I work with the arms, the air noise getting more and more silent (= the air getting out of the system) but when the machine has stand still for ex. and hour, a day or so, and I start it up, the air is back in the system again.

You can replace the hose, but you will need to ensure it is rated for oil. Standard cooling system hose is simply rubber with a braid. Rubber and oil do not like each other and the rubber starts to perrish by becoming soft and will eventually fail. The hose should be quite stiff any way.
Putting a pressure gauge on a line from a cylinder won't tell you much at all. It will simply tell you how much pressure is needed to lift the load. The more weight on the bucket the more pressure is needed. If you wanted to simply tell the condition of the relief valve you hook a gauge to your quick couplers, this will tell you what your relief valve is set to.

 

[sterlclan]

You can replace the hose, but you will need to ensure it is rated for oil. Standard cooling system hose is simply rubber with a braid. Rubber and oil do not like each other and the rubber starts to perrish by becoming soft and will eventually fail. The hose should be quite stiff any way.
Putting a pressure gauge on a line from a cylinder won't tell you much at all. It will simply tell you how much pressure is needed to lift the load. The more weight on the bucket the more pressure is needed. If you wanted to simply tell the condition of the relief valve you hook a gauge to your quick couplers, this will tell you what your relief valve is set to.

do you know what kind of oil is in the hydraulic tank? if the oil is too thick it could cause cavatation in the pump.

 

[mdj]

do you know what kind of oil is in the hydraulic tank? if the oil is too thick it could cause cavatation in the pump.

According the previous owner its regular hydraulic oil, the kind as used for most farmer machine, but he don't now anything else about it.
It's my plan to replace the oil and the filter, so im sure what oil it is.

I pull out the engine today, and what a mess, I discovered on the back end off the hydrostatic, see photo in (mdj bobcat 643)
There is bit off play in the bearing, and it seems to be there the leak is, or what are you mean?
Is it a hard job to replace the bearing and the washer in the back end of the hydrostatic?

As you can see, some of the rips on the cooling fan are broken and some are skew, does that mean anything?

 

[skidsteer.ca]

According the previous owner its regular hydraulic oil, the kind as used for most farmer machine, but he don't now anything else about it.
It's my plan to replace the oil and the filter, so im sure what oil it is.

I pull out the engine today, and what a mess, I discovered on the back end off the hydrostatic, see photo in (mdj bobcat 643)
There is bit off play in the bearing, and it seems to be there the leak is, or what are you mean?
Is it a hard job to replace the bearing and the washer in the back end of the hydrostatic?

As you can see, some of the rips on the cooling fan are broken and some are skew, does that mean anything?

Though I put you pics up here so more would see them.
I'd say you need a new fan, the bent and missing fins could put your engine out of balance and if more fins break they will likely cause other damage. The main air leak is likely the input shaft on the pumps. I'm sure the bearing and seal can be replaced.
Ken

 

[Tazza]

Though I put you pics up here so more would see them.
I'd say you need a new fan, the bent and missing fins could put your engine out of balance and if more fins break they will likely cause other damage. The main air leak is likely the input shaft on the pumps. I'm sure the bearing and seal can be replaced.
Ken

Is the oil leaking from the back of the pump? or is that just from the charge pressure sender? If its the pump i'd have to agree with Ken that you need a new rear seal. The bearing may still be ok, but depending on the state of the old U-Joint it may have damaged it.
I have to agree, the blower isn't in real great shape with those fins, at the very least you may want to take it to a place that does balancing and get them to do whats needed to get it rite.
Just what do you mean a bit of play? Does it wobble from side to side?
You can replace the bearing but this involves pulling the pump out, you then need to remove the rear half of the pump and remove the drive shaft and replace the bearing. If you do this make sure you check the swash plate, make sure it doesn't have excessive wear.

 

[mdj]

Is the oil leaking from the back of the pump? or is that just from the charge pressure sender? If its the pump i'd have to agree with Ken that you need a new rear seal. The bearing may still be ok, but depending on the state of the old U-Joint it may have damaged it.
I have to agree, the blower isn't in real great shape with those fins, at the very least you may want to take it to a place that does balancing and get them to do whats needed to get it rite.
Just what do you mean a bit of play? Does it wobble from side to side?
You can replace the bearing but this involves pulling the pump out, you then need to remove the rear half of the pump and remove the drive shaft and replace the bearing. If you do this make sure you check the swash plate, make sure it doesn't have excessive wear.

Thanks Ken and Tazza
About the fan I agree, it's not god, I should just be sure.

The mess is some grease (I have done the grease job of the u-joint well……a little to well J) and some oil.

And Tazza I don't think it can be from the pressure sender, it has just dribbles a drop or to since I clean it. And with play, yes I mean wobble, …sorry for my English, it's a lot years since I went out of high school.
I hope when it has stand the night over, I can see precisely where the leak is, and if it's the back end of the pump I will take it out and repair it, I will try to take some picture along the way and post it here, but I have still not received my manuals so it can be I while before I get back.

About the swash plate Tazza, can we get back to that when I get the manuals?

I will change the hydraulic oil and filter if the pump must out, but when I put some new oil on, is it enough just to fill the tank up, or should I fill some in the pump to?
What hydraulic oil does you guys use? I have been told that regular hydraulic oil .46 is the one to use, is that right?
Here I Denmark the temperature is for summer about 20-25 degrees Celsius, and the winter about 0 degrees Celsius.

 

[Tazza]

Thanks Ken and Tazza
About the fan I agree, it's not god, I should just be sure.

The mess is some grease (I have done the grease job of the u-joint well……a little to well J) and some oil.

And Tazza I don't think it can be from the pressure sender, it has just dribbles a drop or to since I clean it. And with play, yes I mean wobble, …sorry for my English, it's a lot years since I went out of high school.
I hope when it has stand the night over, I can see precisely where the leak is, and if it's the back end of the pump I will take it out and repair it, I will try to take some picture along the way and post it here, but I have still not received my manuals so it can be I while before I get back.

About the swash plate Tazza, can we get back to that when I get the manuals?

I will change the hydraulic oil and filter if the pump must out, but when I put some new oil on, is it enough just to fill the tank up, or should I fill some in the pump to?
What hydraulic oil does you guys use? I have been told that regular hydraulic oil .46 is the one to use, is that right?
Here I Denmark the temperature is for summer about 20-25 degrees Celsius, and the winter about 0 degrees Celsius.

From those temperatures they are close to what we have in Australia. I run 20W50, 15W40. Basically any car engine oil will do. You will hear some people in here running light oil, especially in winter as their temperatures drop below 0C.
Don't worry about your English, i can still understand it and i'm sure everyone else in here can too.
I don't know if your manual will cover the pump in any detail. Have a look at http://users.tpg.com.au/tazza_/xm2848s.pdf
That will show you what to expect inside the pump. Essentially don't touch the centre part, the bit where the hoses connect to. This section has pressures up to 5,000 PSI. They call the swash plate a wafer plate, it has brass bonded to a steel backing. The rotating group runs on this all the time, over time it will wear a groove into it causing loss of pressure.
Its best to have the pump open and i can explain it better when you can actually see the parts.

 

[skidsteer.ca]

From those temperatures they are close to what we have in Australia. I run 20W50, 15W40. Basically any car engine oil will do. You will hear some people in here running light oil, especially in winter as their temperatures drop below 0C.
Don't worry about your English, i can still understand it and i'm sure everyone else in here can too.
I don't know if your manual will cover the pump in any detail. Have a look at http://users.tpg.com.au/tazza_/xm2848s.pdf
That will show you what to expect inside the pump. Essentially don't touch the centre part, the bit where the hoses connect to. This section has pressures up to 5,000 PSI. They call the swash plate a wafer plate, it has brass bonded to a steel backing. The rotating group runs on this all the time, over time it will wear a groove into it causing loss of pressure.
Its best to have the pump open and i can explain it better when you can actually see the parts.

No idea on what bent the fan all up? If it was run any lenght of time like that then that is likely the reason the bearing is gone on the input shaft to the pumps.
I'd say it is definitely leaking oil there, look at the top photo below the shaft, the pump is all cleaned, where the oil has been running out and washing the dirt away.
Some of the other crud in the bell housing might be grease, but who ever greased those u joints that much? Most of it is oil mixed with dust/dirt imo.
I'll bet the fan is on the spendy side also, though good used should be available, I would think most never get damaged?? . Wonder if the fins could be machined off and electric fans used?
You would loose some flywheel weight, but alot of drag would be gone too.
Ken

 

[Tazza]

No idea on what bent the fan all up? If it was run any lenght of time like that then that is likely the reason the bearing is gone on the input shaft to the pumps.
I'd say it is definitely leaking oil there, look at the top photo below the shaft, the pump is all cleaned, where the oil has been running out and washing the dirt away.
Some of the other crud in the bell housing might be grease, but who ever greased those u joints that much? Most of it is oil mixed with dust/dirt imo.
I'll bet the fan is on the spendy side also, though good used should be available, I would think most never get damaged?? . Wonder if the fins could be machined off and electric fans used?
You would loose some flywheel weight, but alot of drag would be gone too.
Ken

As far as i can think, even with massive vibration from the blower it would do no damage to the pump because it runs a U-Joint. The joint would take all that force out and not transmit it to the pump. BUT if the previous owner ran the machine with bad joints it would indeed do the pump harm. You only need it to be out in one plain and it will shake the poo out of the pump and machine causing the bearing or even the shaft to give way. I would guess thats how the blower was damaged, the old joint let go and hit the fan.
Ken, he did mention he did give it a bit of an over-grease
From what i can see, the fan may not be THAT spendy as it appears to bolt on to the fly wheel unlike the 743 that has it as 1 piece. I don't know how you would go with matching the broken fins on the opposite side, if one was missing on one side you could remove one exactly on the other side. I would do this only as a last resort though. If the engine doesn't vibrate i'd leave it alone. Thermo fans would be interesting, a bit of a pain to setup but i see no reason why it wouldn't work.

 

[sterlclan]

As far as i can think, even with massive vibration from the blower it would do no damage to the pump because it runs a U-Joint. The joint would take all that force out and not transmit it to the pump. BUT if the previous owner ran the machine with bad joints it would indeed do the pump harm. You only need it to be out in one plain and it will shake the poo out of the pump and machine causing the bearing or even the shaft to give way. I would guess thats how the blower was damaged, the old joint let go and hit the fan.
Ken, he did mention he did give it a bit of an over-grease
From what i can see, the fan may not be THAT spendy as it appears to bolt on to the fly wheel unlike the 743 that has it as 1 piece. I don't know how you would go with matching the broken fins on the opposite side, if one was missing on one side you could remove one exactly on the other side. I would do this only as a last resort though. If the engine doesn't vibrate i'd leave it alone. Thermo fans would be interesting, a bit of a pain to setup but i see no reason why it wouldn't work.

It appears that your pump is the same as mine. It wasn't that bad taking it apart . changing the seal and bearing "should" be easy as well. I only changed the seal. yell if you get stuck.......Jeff

 

[mdj]

It appears that your pump is the same as mine. It wasn't that bad taking it apart . changing the seal and bearing "should" be easy as well. I only changed the seal. yell if you get stuck.......Jeff

Thanks for all you reply guys, special thanks Tazza for the draw, that's just what I needed.
Tomorrow I will call the dealer about prices.
What are you thinking, should I replace all the bearing, o-ring and shaft seal in both ends or just replace the bearing and shaft seal in the backend,

BUT another thing, tonight I ware looking at, how the pump where mounted, and in the back end it seems to miss the to nuts ( see photo on mdj bobcat 643 ) that should hold the pump, and I found a nut and a bolt in the mess under the pump, I guess that is what cost all the problems and the broken fan.
Could the missing nut and vibrations of the pump cost the leak you think? If the wobble I can feel is the hold pump I wobble?

 

[Tazza]

Thanks for all you reply guys, special thanks Tazza for the draw, that's just what I needed.
Tomorrow I will call the dealer about prices.
What are you thinking, should I replace all the bearing, o-ring and shaft seal in both ends or just replace the bearing and shaft seal in the backend,

BUT another thing, tonight I ware looking at, how the pump where mounted, and in the back end it seems to miss the to nuts ( see photo on mdj bobcat 643 ) that should hold the pump, and I found a nut and a bolt in the mess under the pump, I guess that is what cost all the problems and the broken fan.
Could the missing nut and vibrations of the pump cost the leak you think? If the wobble I can feel is the hold pump I wobble?

First off, you don't need to get these parts from your dealer, call around your local hydraulics shops that sell eaton/vickers parts. Its just an option.
As for the seals, i would only change the rear bearing and seal, if the other seals do not leak don't touch them, its a little complicated with the ones on the pintle arms (where the steering levers connect to). There is no front seal either, its the hydraulic pump. Unless there are leaks, don't touch those parts as they do not need to be opened.
You are rite, there should be 2 bolts through the back of the pump that hold the pump to the black support that is mounted to the machine. It could indeed have been the cause of the fan damage. Removal of the pump is fairly easy, 4 bolts then 4 main hydraulic hoses which i remove at the motors (i feel its easier that way). 1 charge pressure hose on the top of the pump, 1 high pressure line from the hydraulic pump and 1 suction line to the pump. Plug everything as you remove it.
The missing bolts could indeed be the cause of the vibration, you will always have a little vibration but without support it will be much worse, especially under load.
This pump is indeed the same as sterlclan (Jeff) was talking about. He pulled his pump down and now it works 100%. He does have some pictures in the media section. I have worked on one too so between the 3 of us i'm sure we can point you in the rite direction.

 

[mdj]

First off, you don't need to get these parts from your dealer, call around your local hydraulics shops that sell eaton/vickers parts. Its just an option.
As for the seals, i would only change the rear bearing and seal, if the other seals do not leak don't touch them, its a little complicated with the ones on the pintle arms (where the steering levers connect to). There is no front seal either, its the hydraulic pump. Unless there are leaks, don't touch those parts as they do not need to be opened.
You are rite, there should be 2 bolts through the back of the pump that hold the pump to the black support that is mounted to the machine. It could indeed have been the cause of the fan damage. Removal of the pump is fairly easy, 4 bolts then 4 main hydraulic hoses which i remove at the motors (i feel its easier that way). 1 charge pressure hose on the top of the pump, 1 high pressure line from the hydraulic pump and 1 suction line to the pump. Plug everything as you remove it.
The missing bolts could indeed be the cause of the vibration, you will always have a little vibration but without support it will be much worse, especially under load.
This pump is indeed the same as sterlclan (Jeff) was talking about. He pulled his pump down and now it works 100%. He does have some pictures in the media section. I have worked on one too so between the 3 of us i'm sure we can point you in the rite direction.

Tazza, you don't think I should try to clean it up and mount 2 bolts and put the engine back in again, and se if the leak is gone?

 

[Tazza]

Tazza, you don't think I should try to clean it up and mount 2 bolts and put the engine back in again, and se if the leak is gone?

If you can wobble the shaft you really need to replace the bearing and seal, but if the wobble was not the shaft but the whole pump, its worth a go! Give it a good de-grease.
I seriously doubt the new bolts will stop the leak, if it was me i'd still pull the pump then you know its rite and not the cause of your current problem. As for your earlier question about re-filling the pump, its hard to say. It would be a good idea to fill the pump with a bit of oil but its really not practical as where do you fill it from? The way i did it on a totally drained system was to hook a vacuum cleaner to a line and operate the spool to get oil to flow. It did the job but be sure to use an old vacuum!!!! it will pull a bit of oil up the hose, i found this out the hard way, i wasn't fast enough to turn it off.

 

[sterlclan]

If you can wobble the shaft you really need to replace the bearing and seal, but if the wobble was not the shaft but the whole pump, its worth a go! Give it a good de-grease.
I seriously doubt the new bolts will stop the leak, if it was me i'd still pull the pump then you know its rite and not the cause of your current problem. As for your earlier question about re-filling the pump, its hard to say. It would be a good idea to fill the pump with a bit of oil but its really not practical as where do you fill it from? The way i did it on a totally drained system was to hook a vacuum cleaner to a line and operate the spool to get oil to flow. It did the job but be sure to use an old vacuum!!!! it will pull a bit of oil up the hose, i found this out the hard way, i wasn't fast enough to turn it off.

you should check the allen bolt that holds the splines onto the pump and the keyway behind it mine had a sloppy key which felt like a sloppy shaft .keep us posted.........Jeff

 

[Tazza]

you should check the allen bolt that holds the splines onto the pump and the keyway behind it mine had a sloppy key which felt like a sloppy shaft .keep us posted.........Jeff

One other thing, do not strike the spline on the end of the pump. If it cracks you will need to buy a new one as its locked on to the pump with a taper fit. I know a guy that learnt it the hard way. Re-installed it and couldn't work out why the coupling from the motor would not fit! If you need to remove it use a puller.

 

[sterlclan]

One other thing, do not strike the spline on the end of the pump. If it cracks you will need to buy a new one as its locked on to the pump with a taper fit. I know a guy that learnt it the hard way. Re-installed it and couldn't work out why the coupling from the motor would not fit! If you need to remove it use a puller.

a longer bolt into the shaft and a little tap whilst applying a little pry action behind the splined part worked a treat for me

 

[jerry]

a longer bolt into the shaft and a little tap whilst applying a little pry action behind the splined part worked a treat for me

Be sure that the spline is tight when the allen hd bolt is tight. On our machine the spline would not seat tight as the washer on the bolt hit the end of the shaft first, just a few thousanths but enough. A new one may have fit better but I made a special washer with a relief in it for the shaft and that worked.

 

[Tazza]

Be sure that the spline is tight when the allen hd bolt is tight. On our machine the spline would not seat tight as the washer on the bolt hit the end of the shaft first, just a few thousanths but enough. A new one may have fit better but I made a special washer with a relief in it for the shaft and that worked.

Do ensure its a snug fit when the bolt is tight or you will damage the shaft and spline.

 

[mdj]

Do ensure its a snug fit when the bolt is tight or you will damage the shaft and spline.

Thanks for all yours reply, they are very useful

I have order a new seal to the pump (I can't feel any wobble in the shaft so I hope it can do it with a new seal), as you now, it can be replaced from outside the pump.
When I ordered the seal, I ask the bobcat service guy how to get the spline off, and he use to heat it up a little and pull it off with a puller.
I will get to it this weekend, if I get the new seal, and after a have clean it up (goos I looking forward to that cleaning jobJ) I don't now if I will take the plastic blower house off, I have to pull out the oil cooler if I do so.
I don't replace the blower wheel now……it cost about 1100 US$…..hmmm, I will try to get a used one.

But else have I received the service and parts manual, and its worth all the money, it cover all the machine very very good include ex. the hydraulic pump and hydrostatic, I can only recommend the to manuals.

/Mogens