gjb012
New member
I have a Bobcat 2003 B200 (EF200) with 670 hrs on it, and it has been left unused for long times (hence low hours), but runs well.
The oil and hyd fluid/filter have been changed at 500 hrs and in general the tractor has not been worked hard and has been well maintained.
I recently checked the hyd filter and it was clean as new, with no metal debris or really much of any debris in it at all.
There was some small blue rubber pieces in the bottom, which looked like a seal of some sort in the system that may have degraded.
For someone with in-depth knowledge of the internals of the system - these blue pieces could be an important clue to my problem.
The tractor will move forward and backward sluggishly and without much force when cold, but after running the backhoe/loader/tractor for 5-10 minutes the movement decreases to basically no movement at all. After 30 minutes of use the tractor will not budge in either direction. Allowing it to cool for an hour will get some movement out of it, but very limited, in the morning it will move sluggishly along for a few minutes.
The tractor was working fine until over the course of one day of constant back-hoe use, this forward/reverse degradation of movement happened. It got quickly very bad to the point where the tractor was unusable. I assume it will not move at all soon, cold or hot. I want to use the last bits of life in whatever component is failing to either diagnose the problem or get it on its trailer and off to someone who can fix it.
The hydraulics (loader/backhoe) and steering work perfectly, as does the hydraulic fluid cooler.
The drive safety button to work well - i.e. tractor will not move until it is pressed and once pressed, will move, or at least attempt to move.
The hydraulic brake seems to work, regardless of operating temp, i.e. even of the tractor will not move under its own power, when the pedal is not depressed it still seems to be in brake mode, i.e. will not roll. (I will have to check this again to be absolutely sure this is the case).
The last clue in the scenario is that the backhoe arm piston rod snapped off internally about 4-6 operational hours before this problem started to occur. It was repaired and put back in service. The next day or two this hydrostatic problem started to happen. Perhaps these issues are related in that the cracking of the piston rod may have left metal fragments in the oil...which could have passed through the pump or motor and done it in.
I have the owners, parts and service manuals and have read these and all the threads and advice on this site concerning various failures of the hydrostatic systems. I feel relatively well informed on the workings of the systems having done all this reading, but...
I cannot pin-point the problem after doing some diagnostics. The local Bobcat dealers do not have much experience with this model tractor and I am concerned to bring my issue to them un-diagnosed, and rack of $$ in diagnostics time without a solution. I would prefer to diagnose the problem (if possible) and point them at it; or better yet, just fix it myself. I have done extensive mechanic work in my life and am not worried about the work here....though I would like to diagnose the problem correctly, and not just replace one expensive part after another until the problem is fixed!
My assumptions/understandings are (please correct as I am sure some of these are incorrect):
There are 3 hydraulic pumps: Hydrostatic (31), Charge Pump (21) and Gear Pump (34) (# refer to numbers on schematic)
The hydrostatic pump supplies the power to the drive motor
The Charge pump runs the controls relays and drive pedal for the hydrostatic transmission system
The Gear pump runs the steering motor and the hydraulics (loader/backhoe)
If this was a drive motor shuttle valve (25) or Relief valve (20, 23, 24, 29) it would not be affected so dramatically by the temperature of the fluid nor would it be the same exact behavior in forward and reverse. I am assuming the valves/solenoids would either work or not, i.e. go or not go, and not degrade in both directions with temp.
If the Charge Pump failed, it would affect more than just the forward/backward motion of the tractor - as I assume it does something else than just this control function.
I assume the foot control valves are working well - as this problem is exactly the same in forward and reverse, as I assume if the foot control failed it would work better in one direction than the other.
I am assuming (dreading) it is the drive motor and/or hydrostatic pump - both of which are very expensive and near impossible to get, or even get repair kits for.
My questions are:
1) What do the above symptoms point to as the likely suspect?
2) Are my gross assumptions about ruling out the control valves, solenoids, charge pump valid or should I do more detailed diagnostics on these smaller components?
3) Could it be that a piece of fragment of metal from the backhoe arm piston would NOT be filtered out before it got into the motor or pump? i.e. would returning oil from the arm piston get to the drive motor or hydrostatic pump BEFORE it passed through the filter?
4) if the hyd oil was contaminated could I realistically be looking at a pump AND motor failure or does the fact that the other hyd systems work well indicated the hydrostatic pump is still OK? i.e. does the hydrostatic pump only operate the drive motor or does it operate some other system on the tractor all of which are working?
5) I am assuming (dreading) that the drive motor has failed and have started to investigate getting it rebuilt or replaced:
a) the part/tag number on it (780-0280-170-000) makes no sense to Bobcat or Parker dealer/distributor. No one seems to be able to cross ref this tag number on the German made motor to a current Parker number. I am sure this is a Parker TF/TG/TH series motor but the specs are so exact, without the cross reference to this number, I would be guessing to get the right replacement. Bobcat has said they MAY be able to get the motor for $1800 and 4 weeks delivery time - but no guarantees! Long story short - can anyone help provide a cross reference to a current Parker Model number, i.e. TF 0170 E W 26 0 XXXX?
b) is there some trick to getting the drive motor out, as I have removed all the obvious bolts (6) and hoses and the motor will not budge. I have tried to persuade it out with a mallet and brass hammer, I have even gotten it to rotate IN the casing but it will not come out! Is there a press fit, or worse, a clip or nut on the shaft inside the transmission that prevents it from coming out? I am pulling my hair out trying to remove the motor so I can at least take it to a hyd motor specialist to see if they can test it or cross reference it.
c) is the best way to test the hydrostatic pump by just testing the pressure as detailed in the repair manual on page 30-50-1 - or can we assume it is working because some other system (loader/steering/etc) is working?
Sorry for the long explanation - but I thought it best to give a comprehensive summary for best way to get the best advice on the way forward.
Thanks, Greg
The oil and hyd fluid/filter have been changed at 500 hrs and in general the tractor has not been worked hard and has been well maintained.
I recently checked the hyd filter and it was clean as new, with no metal debris or really much of any debris in it at all.
There was some small blue rubber pieces in the bottom, which looked like a seal of some sort in the system that may have degraded.
For someone with in-depth knowledge of the internals of the system - these blue pieces could be an important clue to my problem.
The tractor will move forward and backward sluggishly and without much force when cold, but after running the backhoe/loader/tractor for 5-10 minutes the movement decreases to basically no movement at all. After 30 minutes of use the tractor will not budge in either direction. Allowing it to cool for an hour will get some movement out of it, but very limited, in the morning it will move sluggishly along for a few minutes.
The tractor was working fine until over the course of one day of constant back-hoe use, this forward/reverse degradation of movement happened. It got quickly very bad to the point where the tractor was unusable. I assume it will not move at all soon, cold or hot. I want to use the last bits of life in whatever component is failing to either diagnose the problem or get it on its trailer and off to someone who can fix it.
The hydraulics (loader/backhoe) and steering work perfectly, as does the hydraulic fluid cooler.
The drive safety button to work well - i.e. tractor will not move until it is pressed and once pressed, will move, or at least attempt to move.
The hydraulic brake seems to work, regardless of operating temp, i.e. even of the tractor will not move under its own power, when the pedal is not depressed it still seems to be in brake mode, i.e. will not roll. (I will have to check this again to be absolutely sure this is the case).
The last clue in the scenario is that the backhoe arm piston rod snapped off internally about 4-6 operational hours before this problem started to occur. It was repaired and put back in service. The next day or two this hydrostatic problem started to happen. Perhaps these issues are related in that the cracking of the piston rod may have left metal fragments in the oil...which could have passed through the pump or motor and done it in.
I have the owners, parts and service manuals and have read these and all the threads and advice on this site concerning various failures of the hydrostatic systems. I feel relatively well informed on the workings of the systems having done all this reading, but...
I cannot pin-point the problem after doing some diagnostics. The local Bobcat dealers do not have much experience with this model tractor and I am concerned to bring my issue to them un-diagnosed, and rack of $$ in diagnostics time without a solution. I would prefer to diagnose the problem (if possible) and point them at it; or better yet, just fix it myself. I have done extensive mechanic work in my life and am not worried about the work here....though I would like to diagnose the problem correctly, and not just replace one expensive part after another until the problem is fixed!
My assumptions/understandings are (please correct as I am sure some of these are incorrect):
There are 3 hydraulic pumps: Hydrostatic (31), Charge Pump (21) and Gear Pump (34) (# refer to numbers on schematic)
The hydrostatic pump supplies the power to the drive motor
The Charge pump runs the controls relays and drive pedal for the hydrostatic transmission system
The Gear pump runs the steering motor and the hydraulics (loader/backhoe)
If this was a drive motor shuttle valve (25) or Relief valve (20, 23, 24, 29) it would not be affected so dramatically by the temperature of the fluid nor would it be the same exact behavior in forward and reverse. I am assuming the valves/solenoids would either work or not, i.e. go or not go, and not degrade in both directions with temp.
If the Charge Pump failed, it would affect more than just the forward/backward motion of the tractor - as I assume it does something else than just this control function.
I assume the foot control valves are working well - as this problem is exactly the same in forward and reverse, as I assume if the foot control failed it would work better in one direction than the other.
I am assuming (dreading) it is the drive motor and/or hydrostatic pump - both of which are very expensive and near impossible to get, or even get repair kits for.
My questions are:
1) What do the above symptoms point to as the likely suspect?
2) Are my gross assumptions about ruling out the control valves, solenoids, charge pump valid or should I do more detailed diagnostics on these smaller components?
3) Could it be that a piece of fragment of metal from the backhoe arm piston would NOT be filtered out before it got into the motor or pump? i.e. would returning oil from the arm piston get to the drive motor or hydrostatic pump BEFORE it passed through the filter?
4) if the hyd oil was contaminated could I realistically be looking at a pump AND motor failure or does the fact that the other hyd systems work well indicated the hydrostatic pump is still OK? i.e. does the hydrostatic pump only operate the drive motor or does it operate some other system on the tractor all of which are working?
5) I am assuming (dreading) that the drive motor has failed and have started to investigate getting it rebuilt or replaced:
a) the part/tag number on it (780-0280-170-000) makes no sense to Bobcat or Parker dealer/distributor. No one seems to be able to cross ref this tag number on the German made motor to a current Parker number. I am sure this is a Parker TF/TG/TH series motor but the specs are so exact, without the cross reference to this number, I would be guessing to get the right replacement. Bobcat has said they MAY be able to get the motor for $1800 and 4 weeks delivery time - but no guarantees! Long story short - can anyone help provide a cross reference to a current Parker Model number, i.e. TF 0170 E W 26 0 XXXX?
b) is there some trick to getting the drive motor out, as I have removed all the obvious bolts (6) and hoses and the motor will not budge. I have tried to persuade it out with a mallet and brass hammer, I have even gotten it to rotate IN the casing but it will not come out! Is there a press fit, or worse, a clip or nut on the shaft inside the transmission that prevents it from coming out? I am pulling my hair out trying to remove the motor so I can at least take it to a hyd motor specialist to see if they can test it or cross reference it.
c) is the best way to test the hydrostatic pump by just testing the pressure as detailed in the repair manual on page 30-50-1 - or can we assume it is working because some other system (loader/steering/etc) is working?
Sorry for the long explanation - but I thought it best to give a comprehensive summary for best way to get the best advice on the way forward.
Thanks, Greg