Bobcat Hydraulic Pump Swash Plate Repair

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Schifference

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Sep 23, 2020
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I have a Bobcat 642 and the right hydro motor makes all kinds of noise and is almost non-responsive. I switched the hoses on the pump from front to back on both sides so that the right handle operates the left hydro motor and the right operates the left. When I did that the problem was no longer on the right side but the left. According to previous posts here and logic, the motor is not the problem but the pump. It has been said that taking the pump out and sanding the swash plates, Wafer plates, and sanding/resurfacing would likely solve the issue. I was fortunate enough to have a moderator Tazza from an old thread respond and offer input on how to do the project. When I put it back in, I hooked up the hoses and filled the reservoir as soon as possible. I left the highest connection undone so the air could bleed out. There was still some air in when I first started the machine. I first raised and tilted the bucket. The hydro's were screaming a bit. I worked the bucket up and down and tilted some more. I drove forward and backward without any turning. The right still seems to be noisier, but some of that could be air. I only ran it for a few minutes then tried it again. All in all I think it is much better. The right motor definitely has power now and moves. I think a few short sessions and air evacuation will probably make it about as good as it will get. Either way, I am not taking it apart again now. If I need to in the future, I have the experience of knowing what is inside. I didn't even mess with anything except the splash plates. I didn't want to risk making it worse and had hopes the splash plates was all it needed. If anyone is interested here is a short video of what I did and what you should expect. https://youtu.be/dq7mPfM__xI
 
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Schifference

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I was not pleased with the outcome after sanding the wear plates. So I decided to remove the pump again. I will have a better video of the process because I had it figured out this time. I was expecting to sand the rotating body where it meets the wear plate and I started to do that and then I found the actual problem. The rotating body is worn around one of the pistons. I should have dug deeper into the unit the first time I had it taken apart. For some reason I thought sanding the swash plates was going to be the fix. I found a new rotating body for less than $400 with 2nd day air. Here is a link to a very short video that shows the worn rotating body. https://youtu.be/omdUjoVXwZE
 

Tazza

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I was not pleased with the outcome after sanding the wear plates. So I decided to remove the pump again. I will have a better video of the process because I had it figured out this time. I was expecting to sand the rotating body where it meets the wear plate and I started to do that and then I found the actual problem. The rotating body is worn around one of the pistons. I should have dug deeper into the unit the first time I had it taken apart. For some reason I thought sanding the swash plates was going to be the fix. I found a new rotating body for less than $400 with 2nd day air. Here is a link to a very short video that shows the worn rotating body. https://youtu.be/omdUjoVXwZE
I'm glad you found the issue, even though it took you needing to pull the pump a second time.
 
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Schifference

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Good Video on Removal of Pump and identification of Wear Plates that need sanding. https://youtu.be/OS4FhW8S0bA
 
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Schifference

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Good Video on Removal of Pump and identification of Wear Plates that need sanding. https://youtu.be/OS4FhW8S0bA
I received the new rotating group today. It came complete. It looked dry so I dunked it into some oil and soaked if for a few minutes. Put it all back together and it runs great.
 

Tazza

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I received the new rotating group today. It came complete. It looked dry so I dunked it into some oil and soaked if for a few minutes. Put it all back together and it runs great.
Wow, LPS did a great job getting it to you so fast.
Glad it's up and running as it should. You didn't have any issues with the 3 pins you had concerns about? hopefully it came with the cage that makes it super easy to install.
 
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Schifference

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Wow, LPS did a great job getting it to you so fast.
Glad it's up and running as it should. You didn't have any issues with the 3 pins you had concerns about? hopefully it came with the cage that makes it super easy to install.
I paid for second day air. Yes the pins were included and must have been in a cage because they were not falling out. As mentioned previously the unit was dry. So prior to installation, I soaked it in hydraulic oil. I wanted to express my thanks to you Tazza for your willingness to correspond with me on this issue. If it were not for a very old thread where you had told a forum member to contact you by email with questions, I would have had no guidance. Hopefully the video I made will be helpful for anyone that is having drive issues with their 642. On another note, I cannot imagine the electrical system on the 642 to be very complex. Why would you think my battery keeps going dead? Fully charged and next day dead. What could be draining it while it sits? I put a $12 battery disconnect switch on it yesterday to keep it from happening but I was just wondering where you would look. Thanks for all the help!
 

foton

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Mar 1, 2018
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I paid for second day air. Yes the pins were included and must have been in a cage because they were not falling out. As mentioned previously the unit was dry. So prior to installation, I soaked it in hydraulic oil. I wanted to express my thanks to you Tazza for your willingness to correspond with me on this issue. If it were not for a very old thread where you had told a forum member to contact you by email with questions, I would have had no guidance. Hopefully the video I made will be helpful for anyone that is having drive issues with their 642. On another note, I cannot imagine the electrical system on the 642 to be very complex. Why would you think my battery keeps going dead? Fully charged and next day dead. What could be draining it while it sits? I put a $12 battery disconnect switch on it yesterday to keep it from happening but I was just wondering where you would look. Thanks for all the help!
if you have a amp meter put it line between the battery disconnect and the battery cable to the starter relay with everything off and look for drain amount. Ideally there should be no drain , not even milliamps. If there is it is just a matter of chasing it down.
 
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