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Bobcat Skidsteer Forums
General Bobcat Skidsteer Forum
853, hydrostatic pump leaks on top, easy to fix??
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<blockquote data-quote="thetool" data-source="post: 20623" data-attributes="member: 1534"><p>Okay-you don't have to pull your pump out and down to fix it.</p><p>If you remove the cable by removing the nuts and bolts at the lever, and the bracket bolts on the servo cover, you swing the cable out of the way, and you're ready to proceed.</p><p>You really need to dump the oil or it will drain the tank.</p><p>Clean off the top and mark the v-notch on the bracket, remove the sector adustment bolt and pull the assembly straight out. This will be the spool, the adjustment bracket, a clothespin-type spring and the lever all held together with a nut on top of the spool. There's an 0-ring and a white teflon back-up ring on the spool. If the spring is broken, as they commonly are, you have to disassemble this assembly to replace it, so you have to note the orientation of the spool to the bracket, because it has weird metering notches cut into it and it's not symmetrical.</p><p>Now your sleeve is still in the bore of the pump, and it's tough to pull out. It sticks up out of the pump about 1/4". Around this sleeve is where it commonly leaks. Dirt gets in the bore around the sleeve and takes out the o-ring and back-up ring(same as the spool, but larger diameter) AND puts a groove in the bore of the pump housing, which makes it almost impossible to repair by replacing the o-ring.</p><p>So for big bucks, but far less than the cost of a new pump, Bobcat offers replacement sleeves that have an o-ring groove further down on the sleeve from the top, so your new o-ring has a new, ungrooved contact surface, along with some protection washers to keep the dirt out in the future.</p><p>To pull the sleeve, I get a pair of vise grips, adjusted tight enough that it won't slip on the sleeve, but not so tight that it marks it. Clamp the vise-grip onto the sleeve, vise-grip horizontal, and use a pry-bar under the jaws of the vise-grip, between the jaws and the top of the pump, hold down with my hand on the vise grip handle and gently pry the sleeve straight up and out.</p><p>New sleeve or old, it has a notch cut out of the bottom of the sleeve. This notch indexes on a pin down inside the pump, and if you don't line it up squarely, it won't go in. The notch faces the servo when it goes in, and has to be exactly perpendicular to the long axis of the pump to catch the pin. </p><p>The sleeve will go down and stop short. This is where guys get impatient and tap it with a hammer and shear that little pin down in there. DON'T DOO DAT!.....=).</p><p>If everything's lined up, it will go down with hand pressure only. Both thumbs pushing down and it will pop in.</p><p>If you pay attention to your spool orientation, don't use a hammer or any other tapping or pounding device, don't mess with the cable lengths, line the notch on the bracket and get it back together in the same place, you shouldn't have any problems.</p><p>The parts breakdown list has all the parts you need, but there is more detail in the service letter I mentioned, more detail that in the service manual. Often the dust washers are neglected, I think they're important. Those sleeves are about $300 each and I think bobcat quotes the pump at $6K, 'cause it's no longer in production.</p><p>I also like to double o-ring instead of the back-up washer on the sleeve. Sometimes this will get you by without the updated sleeve, but get the dust washers regardless.</p><p>It sounds more complicated than it really is, and I'm sure you can do it.</p></blockquote><p></p>
[QUOTE="thetool, post: 20623, member: 1534"] Okay-you don't have to pull your pump out and down to fix it. If you remove the cable by removing the nuts and bolts at the lever, and the bracket bolts on the servo cover, you swing the cable out of the way, and you're ready to proceed. You really need to dump the oil or it will drain the tank. Clean off the top and mark the v-notch on the bracket, remove the sector adustment bolt and pull the assembly straight out. This will be the spool, the adjustment bracket, a clothespin-type spring and the lever all held together with a nut on top of the spool. There's an 0-ring and a white teflon back-up ring on the spool. If the spring is broken, as they commonly are, you have to disassemble this assembly to replace it, so you have to note the orientation of the spool to the bracket, because it has weird metering notches cut into it and it's not symmetrical. Now your sleeve is still in the bore of the pump, and it's tough to pull out. It sticks up out of the pump about 1/4”. Around this sleeve is where it commonly leaks. Dirt gets in the bore around the sleeve and takes out the o-ring and back-up ring(same as the spool, but larger diameter) AND puts a groove in the bore of the pump housing, which makes it almost impossible to repair by replacing the o-ring. So for big bucks, but far less than the cost of a new pump, Bobcat offers replacement sleeves that have an o-ring groove further down on the sleeve from the top, so your new o-ring has a new, ungrooved contact surface, along with some protection washers to keep the dirt out in the future. To pull the sleeve, I get a pair of vise grips, adjusted tight enough that it won't slip on the sleeve, but not so tight that it marks it. Clamp the vise-grip onto the sleeve, vise-grip horizontal, and use a pry-bar under the jaws of the vise-grip, between the jaws and the top of the pump, hold down with my hand on the vise grip handle and gently pry the sleeve straight up and out. New sleeve or old, it has a notch cut out of the bottom of the sleeve. This notch indexes on a pin down inside the pump, and if you don't line it up squarely, it won't go in. The notch faces the servo when it goes in, and has to be exactly perpendicular to the long axis of the pump to catch the pin. The sleeve will go down and stop short. This is where guys get impatient and tap it with a hammer and shear that little pin down in there. DON'T DOO DAT!.....=). If everything's lined up, it will go down with hand pressure only. Both thumbs pushing down and it will pop in. If you pay attention to your spool orientation, don't use a hammer or any other tapping or pounding device, don't mess with the cable lengths, line the notch on the bracket and get it back together in the same place, you shouldn't have any problems. The parts breakdown list has all the parts you need, but there is more detail in the service letter I mentioned, more detail that in the service manual. Often the dust washers are neglected, I think they're important. Those sleeves are about $300 each and I think bobcat quotes the pump at $6K, 'cause it's no longer in production. I also like to double o-ring instead of the back-up washer on the sleeve. Sometimes this will get you by without the updated sleeve, but get the dust washers regardless. It sounds more complicated than it really is, and I'm sure you can do it. [/QUOTE]
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853, hydrostatic pump leaks on top, easy to fix??
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