753 Has trouble with right reverse after it warms up

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Keith

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Joined
Sep 28, 2007
Messages
14
I have a 1993 Bobcat 753 that I just purchased. The unit operates properly for the first ten minutes or so. Once it warms up the right motor does not want to drive in reverse. It will go forward fine and the left motor cotinues to function in forward or reverse. Since it works OK for the first few minutes I don't think it is linkage? The hydraulic fluid looks like it is actual hydraulic fluid. The manual says it will ron 10-30 or 10-40 motor oil in the hydraulics. I also thought that it may be a problem with one of the replenishing valves. What I can't figure out though is why it works cold but not once it is warm? Any thoughts or suggestions would be most appreciated!
 

sterlclan

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Joined
May 1, 2004
Messages
528
As the fluid warms up it gets thinner...could be a valve issue or a filter I don't know if you have case drain filter changing the filter and fluid may help you can check the valve too might be some crud in it...If you don't have a service manual you should get one they are worth every penny good luck........... Jeff
 

Keith

Member
Joined
Sep 28, 2007
Messages
14
As the fluid warms up it gets thinner...could be a valve issue or a filter I don't know if you have case drain filter changing the filter and fluid may help you can check the valve too might be some crud in it...If you don't have a service manual you should get one they are worth every penny good luck........... Jeff
Jeff, Thanks for the reply! I do have a manual that I purchased off ebay. Of course it covers a wide range of serial numbers so I have learned that I have to verify that the book and the machine match. Sometimes they do ....sometimes not. According to the book it looks like it has two case drain filters. One in the line from the hydraulic reservor and one between the left drive motor and the hydrostatic transmission. I will have to dig around and see if I can recognize them. As for the repenishing valves, it looks like two face forward and two face the engine. Is it possible to get to the two facing the engine with the pump still in the machine?.......Thanks! Keith
 

sterlclan

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Joined
May 1, 2004
Messages
528
Jeff, Thanks for the reply! I do have a manual that I purchased off ebay. Of course it covers a wide range of serial numbers so I have learned that I have to verify that the book and the machine match. Sometimes they do ....sometimes not. According to the book it looks like it has two case drain filters. One in the line from the hydraulic reservor and one between the left drive motor and the hydrostatic transmission. I will have to dig around and see if I can recognize them. As for the repenishing valves, it looks like two face forward and two face the engine. Is it possible to get to the two facing the engine with the pump still in the machine?.......Thanks! Keith
I haven't worked on a transverse pump before, I suppose you could get at them after tipping the cab. others here have way more practice on this type of machine than me good luck....Jeff
 

Keith

Member
Joined
Sep 28, 2007
Messages
14
I haven't worked on a transverse pump before, I suppose you could get at them after tipping the cab. others here have way more practice on this type of machine than me good luck....Jeff
I'm having a hard time locating the replenishing valves. The hyrostatic pump in the machine is a model M91-35916R. In the service maual on the page that shows the hyrostatic flow chart it shows the replenishing valves as being on the hyrostatic pump? When I look at the parts book it does not make reference to replenishing valves on the parts list for the pump? I do see a check vale and a relief vale but when I look at the unit itself I'm not even sure where they are located. Are they on the bottom of the hydrostatic pump? ....Thanks! Keith
 

sterlclan

Well-known member
Joined
May 1, 2004
Messages
528
I'm having a hard time locating the replenishing valves. The hyrostatic pump in the machine is a model M91-35916R. In the service maual on the page that shows the hyrostatic flow chart it shows the replenishing valves as being on the hyrostatic pump? When I look at the parts book it does not make reference to replenishing valves on the parts list for the pump? I do see a check vale and a relief vale but when I look at the unit itself I'm not even sure where they are located. Are they on the bottom of the hydrostatic pump? ....Thanks! Keith
on mine they are in the middle of the pump,hydraulic on front hystat then valve body with another hystat pump bolted to that ,they may be on top and bottom of yours follow the hoses from the drive motor back to the pump the valves should be in that section of pump,I read somewhere that the later ones are under the pump. the parts book probably has them listed as a poppet if all else fails call your bobcat dealer they are usually willing to help.......Jeff
 
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