Painting a Bobcat

[Tazza]

Ok, i bought a 743 in April that had an engine bay fire, i have since re-conditioned the engine and re-cored the radiator, i have only had it moving for a few minutes a a few hydro lines were burnt and oil was leaking out. I just ran it to see if the hydrostatics were still working, and they seem to be ok.

My plan it to remove EVERYTHING but the hydro motors off the chain case and axles. Then ream the bushes and make new pins then paint. Are there any tricks to this? or just go wild removing bits, plugging hydro lines and a lot of de-greasing. I know it is going to be a big job, but i do have the luxury of having 2 other machines so a time factor isn't a big deal.

Should i be replacing anything when it is in pieces? like axle seals that don't seem to be leaking. I will be pulling the hydro pump apart and facing the swash plates. I will also re-seal the control block. Anything else i should be looking at?
I have machined new pistons and gland nuts for the lift arm rams, new seals and chrome bar will be used to finish them off. I will do the same to the tilt ram.
Any and all suggestions are welcome.

 

[goodtech]

In seven years of working on bobcats I have NOT scene any problems with the 734 hydrostats until someone thinks that there is a problem with them. They are indestructable until someone opens them up and starts playing with them. I have seen machines with 20,000 plus hrs on them with nothing wrong with the hydrostat. May I ask why do you want to tear it apart and face the plates? Then you should also replace the pistons in the pump so everything breaks in togethere according to bobcat tech schools. Everything else you want to replace in it sounds like a great idea. I also recommed changing the two steel lines that run under the fan shroud because if there was that much heat in there It would be well worth your time. Good luck on painting

 

[goodtech]

Sorry I forgot to tell you also while you are in there I would would get rid of that fuel filter mess and mount yourself a nice spin on filter also you can find them on any of the newer bobcats, that makes life alot easier when you do service them, and not near the mess.

 

[Tazza]

Sorry I forgot to tell you also while you are in there I would would get rid of that fuel filter mess and mount yourself a nice spin on filter also you can find them on any of the newer bobcats, that makes life alot easier when you do service them, and not near the mess.

Thanks for the reply.

I know a guy that repairs bobcats and he said that i should hack open the hydro pump just to make sure that there is no wear. He said to make sure the swash plates have no scores and that the shoes of the pistons don't have and sharp edges. If there were sharp edges i should wipe them over with fine wet and dry sand paper (just the sides of the shoe). If not, when the pieces come off in time as it wears more, they will lodge in places that you don't want them. He did say not to mess with the high pressure section (the center part). Just check the rotating groups and swash plates ooh and to replace the seal at the back. As we don't know just how hot it got, it should be replaced.

The fire couldn't have been too hot, it melted the plastic blower housing, ate all the fuel lines and started melting a very small amount of the radiator. No engine parts were melted, the oil cooler survived. One tube line was already replaced with a hose (melted), so i will get 2 new ones as you advised.

I wish i asked this earlier, i have already bought the fuel filter and housing.... the same style as the old one, but i think i will move its location, it is in a terrible spot.....

Getting back to the hydro pump, i have another 743 that i got not too long ago (fell off the back of a truck, no really!) It was making horrible grinding sounds when you try to start it, and the right steering lever shook like mad. I was told it could be the rotating group so i figured i may as well have a look. I managed to get it apart and back together without any problems (or any left over parts). I faced the swash plates while i was in there to remove a few scores it had, i did this with sheets of wet and dry, oil and a sheet of glass as a flat surface. I didn't touch the pistons, they were nice and smooth, no sharp edges. Its all back together with no problems and has heaps of power. Like all hydraulics, keep it clean! and use plenty of oil when re-assembling it. I also had an exploded view so i knew where it all went, and what orientation of the parts.

The only problem is getting it to center.... i just can't get it rite. If i have the park brake on and let the revs get low, some times you hear it grind as it tries to move and then throws a lever forward and stalls. This is what the problem was in the first place! so i didn't need to remove the rotten pump.

So, you don't think i should pull the pump apart to check it for wear? i just don't know what condition its in, i have only run it for like 5 mins and that was at idle, it span the left hand side wheels just idling up against a post, i didn't check the right hand side but it did turn so both sides did function. Its not a thing i really want to have to remove and re-install again... its not fun. Its a job i would prefer to do only once.

 

[Tazza]

Thanks for the reply.

I know a guy that repairs bobcats and he said that i should hack open the hydro pump just to make sure that there is no wear. He said to make sure the swash plates have no scores and that the shoes of the pistons don't have and sharp edges. If there were sharp edges i should wipe them over with fine wet and dry sand paper (just the sides of the shoe). If not, when the pieces come off in time as it wears more, they will lodge in places that you don't want them. He did say not to mess with the high pressure section (the center part). Just check the rotating groups and swash plates ooh and to replace the seal at the back. As we don't know just how hot it got, it should be replaced.

The fire couldn't have been too hot, it melted the plastic blower housing, ate all the fuel lines and started melting a very small amount of the radiator. No engine parts were melted, the oil cooler survived. One tube line was already replaced with a hose (melted), so i will get 2 new ones as you advised.

I wish i asked this earlier, i have already bought the fuel filter and housing.... the same style as the old one, but i think i will move its location, it is in a terrible spot.....

Getting back to the hydro pump, i have another 743 that i got not too long ago (fell off the back of a truck, no really!) It was making horrible grinding sounds when you try to start it, and the right steering lever shook like mad. I was told it could be the rotating group so i figured i may as well have a look. I managed to get it apart and back together without any problems (or any left over parts). I faced the swash plates while i was in there to remove a few scores it had, i did this with sheets of wet and dry, oil and a sheet of glass as a flat surface. I didn't touch the pistons, they were nice and smooth, no sharp edges. Its all back together with no problems and has heaps of power. Like all hydraulics, keep it clean! and use plenty of oil when re-assembling it. I also had an exploded view so i knew where it all went, and what orientation of the parts.

The only problem is getting it to center.... i just can't get it rite. If i have the park brake on and let the revs get low, some times you hear it grind as it tries to move and then throws a lever forward and stalls. This is what the problem was in the first place! so i didn't need to remove the rotten pump.

So, you don't think i should pull the pump apart to check it for wear? i just don't know what condition its in, i have only run it for like 5 mins and that was at idle, it span the left hand side wheels just idling up against a post, i didn't check the right hand side but it did turn so both sides did function. Its not a thing i really want to have to remove and re-install again... its not fun. Its a job i would prefer to do only once.

When i thought about it, you are rite. If i face the swash plates i would have to do the front of the rotating group too, as it would have the same wear marks. So i really should leave it alone, the small amount of performance increase by having them back to factory spec just isn't worth the hassle.

 

[goodtech]

Thanks for the reply.

I know a guy that repairs bobcats and he said that i should hack open the hydro pump just to make sure that there is no wear. He said to make sure the swash plates have no scores and that the shoes of the pistons don't have and sharp edges. If there were sharp edges i should wipe them over with fine wet and dry sand paper (just the sides of the shoe). If not, when the pieces come off in time as it wears more, they will lodge in places that you don't want them. He did say not to mess with the high pressure section (the center part). Just check the rotating groups and swash plates ooh and to replace the seal at the back. As we don't know just how hot it got, it should be replaced.

The fire couldn't have been too hot, it melted the plastic blower housing, ate all the fuel lines and started melting a very small amount of the radiator. No engine parts were melted, the oil cooler survived. One tube line was already replaced with a hose (melted), so i will get 2 new ones as you advised.

I wish i asked this earlier, i have already bought the fuel filter and housing.... the same style as the old one, but i think i will move its location, it is in a terrible spot.....

Getting back to the hydro pump, i have another 743 that i got not too long ago (fell off the back of a truck, no really!) It was making horrible grinding sounds when you try to start it, and the right steering lever shook like mad. I was told it could be the rotating group so i figured i may as well have a look. I managed to get it apart and back together without any problems (or any left over parts). I faced the swash plates while i was in there to remove a few scores it had, i did this with sheets of wet and dry, oil and a sheet of glass as a flat surface. I didn't touch the pistons, they were nice and smooth, no sharp edges. Its all back together with no problems and has heaps of power. Like all hydraulics, keep it clean! and use plenty of oil when re-assembling it. I also had an exploded view so i knew where it all went, and what orientation of the parts.

The only problem is getting it to center.... i just can't get it rite. If i have the park brake on and let the revs get low, some times you hear it grind as it tries to move and then throws a lever forward and stalls. This is what the problem was in the first place! so i didn't need to remove the rotten pump.

So, you don't think i should pull the pump apart to check it for wear? i just don't know what condition its in, i have only run it for like 5 mins and that was at idle, it span the left hand side wheels just idling up against a post, i didn't check the right hand side but it did turn so both sides did function. Its not a thing i really want to have to remove and re-install again... its not fun. Its a job i would prefer to do only once.

Those 743 can be a bitch to get them to center. It is not the pump, some are just touchy more than others. It just takes alot of time and sometimes alot of beer drinking to get those 743 and 742 to adjust at neutral. I have spent well over six hrs getting one before, just follow your manual to a tee and you will eventaully get it. Make sure that those round pucks that they center against do not have a flat spot on them because that will make it 10 harder yet. but that is the reason your unit is growling because you are not centered and it sending oil to the motors which are trying to turn the chains. Good luck