Bobcat 753 replenishing valve ?

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cjshocco

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Apr 15, 2012
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Hey my name is Chris I just got this Bobcat when going forward the right side will stall for a second then it will go or if when it stalls if you reverse it then go forward it helps some. Reverse on the right side work fine and the forward and reverse on the left side work fine as well. The linkage appears to be right. Just searching on the web I read it may be a problem with the replenishing valve . What do you all think ? My shop manual has almost no info on this valve . Can you tell me wear it is located at and can it be cleaned or will it need to be replaced . When the machine gets warm is when it starts this . When it is working it is srong it will spin the tires under a load. Any help would be greatly appreciated . I believe it is a 97 model. Thank you, Chris
 

Tazza

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Have you changed the main filter?
Does the charge pressure warning light come on at all?
I wonder if its something is bad as leaky motor seals. When it gets warmer the oil thins out, so it will by-pass more easily.
With the cab up, get a screwdriver under the linkages from the steering levers to the pump, look at the alloy blocks that bolt to the arms on the pump. See if you can lift them up with a screwdriver. Push down and then lever up. Do they move at all? even a little means they are loose and possibly worn.
 
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cjshocco

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Apr 15, 2012
Messages
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Have you changed the main filter?
Does the charge pressure warning light come on at all?
I wonder if its something is bad as leaky motor seals. When it gets warmer the oil thins out, so it will by-pass more easily.
With the cab up, get a screwdriver under the linkages from the steering levers to the pump, look at the alloy blocks that bolt to the arms on the pump. See if you can lift them up with a screwdriver. Push down and then lever up. Do they move at all? even a little means they are loose and possibly worn.
I changed the filter this afternoon no difference . No lights on . I'll look at the linkage in the next couple of days when I can get back to it. Thank you for the info. Do the replenishing valves ever give trouble and are they easy to check ? Thank you, Chris
 

Tazza

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I changed the filter this afternoon no difference . No lights on . I'll look at the linkage in the next couple of days when I can get back to it. Thank you for the info. Do the replenishing valves ever give trouble and are they easy to check ? Thank you, Chris
Its always a possibility that its the problem. They are not easy to access. I can't remember exactly where they are and what ones what direction. I think they are a combination relief/replenishing valve. If you lift the cab and look at the pump, there will be two allen headed plugs on the top and two underneath where you can't see.
 

7LBSSMALLIE

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Feb 2, 2012
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Its always a possibility that its the problem. They are not easy to access. I can't remember exactly where they are and what ones what direction. I think they are a combination relief/replenishing valve. If you lift the cab and look at the pump, there will be two allen headed plugs on the top and two underneath where you can't see.
relief replenish valve failure rare, cap off motors if stat pulls down to stall both sides both directions, stat good most likley in motors either a hi to low leak or stuck shuttle valve. motor reseal easy parts nominal, easy enough to pull motor tear down inspect and reseal ,note motors need timed,
 
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cjshocco

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Apr 15, 2012
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relief replenish valve failure rare, cap off motors if stat pulls down to stall both sides both directions, stat good most likley in motors either a hi to low leak or stuck shuttle valve. motor reseal easy parts nominal, easy enough to pull motor tear down inspect and reseal ,note motors need timed,
Hey thanks for the info !! I worked late today ,maybe I can get to it tomorrow . I hate to ask a dumb question but you have a idea on the size of the cap or plug I would need ? I'm really not good on hyd line sizes. Thank you, Chris
 
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cjshocco

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Apr 15, 2012
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Have you changed the main filter?
Does the charge pressure warning light come on at all?
I wonder if its something is bad as leaky motor seals. When it gets warmer the oil thins out, so it will by-pass more easily.
With the cab up, get a screwdriver under the linkages from the steering levers to the pump, look at the alloy blocks that bolt to the arms on the pump. See if you can lift them up with a screwdriver. Push down and then lever up. Do they move at all? even a little means they are loose and possibly worn.
I got around to getting it up to my fathers shop to pressure wash it to do some checking. I noticed today that the right side reverse does the same thing kinda , and if you push both levers in the same direction at the same time it will not give trouble . If you lead off with the right (the side giving the trouble) it will give trouble but not reverse. I will look at some of the things you all mentioned in the next couple of days and let you know what I find . I wanted to mention this also it may help . Thank you , Chris
 

Fishfiles

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Feb 8, 2007
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I got around to getting it up to my fathers shop to pressure wash it to do some checking. I noticed today that the right side reverse does the same thing kinda , and if you push both levers in the same direction at the same time it will not give trouble . If you lead off with the right (the side giving the trouble) it will give trouble but not reverse. I will look at some of the things you all mentioned in the next couple of days and let you know what I find . I wanted to mention this also it may help . Thank you , Chris
check and clean the case drain filters, you will probally find some pieces of oring and or plastic back up rings from the travel motor , I would think it is the seals inside the travel motor that is causing your problem , to order a seal kit for that machine it is best to pukk the motor and find the tag on it as the serial number doesn't always get you the correct kit
 
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cjshocco

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Apr 15, 2012
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check and clean the case drain filters, you will probally find some pieces of oring and or plastic back up rings from the travel motor , I would think it is the seals inside the travel motor that is causing your problem , to order a seal kit for that machine it is best to pukk the motor and find the tag on it as the serial number doesn't always get you the correct kit
Thank you , I will check that also !!
 

Tazza

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Thank you , I will check that also !!
To add to Fishfiles advise, i got lucky with my motors. It used the older style motors that used standard O rings. It cost me $10 for two motors. A lot better than the $100 or so each from the dealer.
I'd recommend pulling the motor down before ordering any seals. If the plastic backup rings are ok, i'd re-use them and install new O rings. The newer ones with moulded seals, you will need to buy a new seal kitl
 
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cjshocco

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To add to Fishfiles advise, i got lucky with my motors. It used the older style motors that used standard O rings. It cost me $10 for two motors. A lot better than the $100 or so each from the dealer.
I'd recommend pulling the motor down before ordering any seals. If the plastic backup rings are ok, i'd re-use them and install new O rings. The newer ones with moulded seals, you will need to buy a new seal kitl
Sounds like yall know your stuff . This is a great site . I got home from work about 30 min before dark . So I guess another day before I get at it . Thank you for the lesson . Chris
 
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cjshocco

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Apr 15, 2012
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To add to Fishfiles advise, i got lucky with my motors. It used the older style motors that used standard O rings. It cost me $10 for two motors. A lot better than the $100 or so each from the dealer.
I'd recommend pulling the motor down before ordering any seals. If the plastic backup rings are ok, i'd re-use them and install new O rings. The newer ones with moulded seals, you will need to buy a new seal kitl
I got around to cleaning and getting at my Bobcat today . I looked at the linkages again and they looked good . I took the filter off that comes back to the hyd tank and it had five little shivers of steel, some small gray rubber plastic pieces , and about a tea spoon of trash. What do you all think based on what was in the filter ? It got dark on me before I got the other small filter off . I think I will clean the other filter in the morning , then swicth the two pumps and see what happens . Or would you just go ahead and take the pump apart ?
 
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cjshocco

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Apr 15, 2012
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check and clean the case drain filters, you will probally find some pieces of oring and or plastic back up rings from the travel motor , I would think it is the seals inside the travel motor that is causing your problem , to order a seal kit for that machine it is best to pukk the motor and find the tag on it as the serial number doesn't always get you the correct kit
I pulled the pump apart today the seals against the back part of the pump where broke apart and some of the pieces were gone . Think this was causing the problem ? I saw some seals on loader parts source for a little over $100 .
 
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cjshocco

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Apr 15, 2012
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I pulled the pump apart today the seals against the back part of the pump where broke apart and some of the pieces were gone . Think this was causing the problem ? I saw some seals on loader parts source for a little over $100 .
Oh yeah , thank you all for all the very helpful info . Without you guys I would probally still be scrathing my head .
 
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cjshocco

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Oh yeah , thank you all for all the very helpful info . Without you guys I would probally still be scrathing my head .
I talked with the nearest hyd shop and he was almost ticked off that I had pulled it apart . I punch marked the housing and marked the position of the shaft and did not pull the shaft or rollers out. I am pretty mechanically inclined should I try to put the seals in and put it back together. He sales the seals for around $50 and would put the seals in and time it for $100 . He said if it was not timed right it would mess up the shaft . Do you think that is right ?
 

waggles

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Oct 9, 2009
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I talked with the nearest hyd shop and he was almost ticked off that I had pulled it apart . I punch marked the housing and marked the position of the shaft and did not pull the shaft or rollers out. I am pretty mechanically inclined should I try to put the seals in and put it back together. He sales the seals for around $50 and would put the seals in and time it for $100 . He said if it was not timed right it would mess up the shaft . Do you think that is right ?
Do a search on Eaton /Charlyn 30series bearingless motors and down load the repair PDF , it shows you how to do it, and part numbers . Its not hard just follow the repair guide.
 

Fishfiles

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Do a search on Eaton /Charlyn 30series bearingless motors and down load the repair PDF , it shows you how to do it, and part numbers . Its not hard just follow the repair guide.
ya know , I thought about telling you to mark the index of the motor before taking it apart but it slipped my mind , it was as simple as using a chiesel or die grinder and marking 1-1 , 11-11, 111-111 on the sections of the housing , you should still be able to figure it out by markings , as far as timing goes I don't know what he is talking about , unless what he is calling timing is really indexing , which it does have to be aligned the same way it came apart , the fittings have to be in the right position as well as the mounting flange ------------$100 for the seals and putting it back together isn't bad
 
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cjshocco

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Apr 15, 2012
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ya know , I thought about telling you to mark the index of the motor before taking it apart but it slipped my mind , it was as simple as using a chiesel or die grinder and marking 1-1 , 11-11, 111-111 on the sections of the housing , you should still be able to figure it out by markings , as far as timing goes I don't know what he is talking about , unless what he is calling timing is really indexing , which it does have to be aligned the same way it came apart , the fittings have to be in the right position as well as the mounting flange ------------$100 for the seals and putting it back together isn't bad
Well I finally got my drive motor back yesterday . The hyd. shop installed a seal kit. I was told $150 but it cost $360 . It took him forever to get the right kit. Anyway I got it back on this evening and it now works great . Thank you all for the very helpful information .
 
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