Bobcat 853 and Boss Problem

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conc2steel

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Dec 30, 2007
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I have a Bobcat 853 with Boss that has suddenly stopped working. The Bobcat was being used to move some dirt and cameto a stump, when trying to lift the stump the vehicle stalled and an error came up on the Boss: HP. After 30 second I could start the system, bu none of the hydraulics work, it won't back up (or go forward). After about 30 seconds, the engine shuts down and the Boss shows HP as the error again. I've checked all fluids, they look good. The machine was services about 3 months ago and has only been run about 8 hours since the service. Any ideas?
 
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conc2steel

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Dec 30, 2007
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Check your drive belt. It may have broke or the tensioner could have loosened up.
You nailed it! That puppy is was broken as can be, as soon as I took the belt cover off the broke end stuck out. Now I just need to get a new belt and replace it... any idea how difficult it is to replace... looks a bit cramped in the engine compartment!
 

scar99

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Dec 24, 2007
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You nailed it! That puppy is was broken as can be, as soon as I took the belt cover off the broke end stuck out. Now I just need to get a new belt and replace it... any idea how difficult it is to replace... looks a bit cramped in the engine compartment!
Glad I cold help. There should be a sticker on the inside of the tail gate that shows how to do it. It has been awhile since I have done one on an 853. But I dont remember them being to hard.
 

skidsteer.ca

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Jan 20, 2006
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Glad I cold help. There should be a sticker on the inside of the tail gate that shows how to do it. It has been awhile since I have done one on an 853. But I dont remember them being to hard.
The 853 is no worse then any other model to change the belt, but the belt does not use a spring loaded tensioner (at least on mine) so expect to retension it after 20 hours or so.
Further the tensioner bearing is lubed with oil, lay it bracket side down, pop the dust cap off (just like a trailer hub dust cap) the oil should be up to the top edge of the top bearing (the way it laying) and there should be almost no play in the bearings (say .005" or less) Silicone the cap and re install.
I believe they called for a synthetic motor oil.
Ken
 
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conc2steel

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The 853 is no worse then any other model to change the belt, but the belt does not use a spring loaded tensioner (at least on mine) so expect to retension it after 20 hours or so.
Further the tensioner bearing is lubed with oil, lay it bracket side down, pop the dust cap off (just like a trailer hub dust cap) the oil should be up to the top edge of the top bearing (the way it laying) and there should be almost no play in the bearings (say .005" or less) Silicone the cap and re install.
I believe they called for a synthetic motor oil.
Ken
i've got a bit of a challenge. The belt broke and wrapped around one of the pullies (no the drive pully attached to the engine). It has wrapped around the hydraulics pully and is wedged between the pully and case... it won't move at all. Any idea how to get the belt off?
 

perry

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Aug 22, 2006
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i've got a bit of a challenge. The belt broke and wrapped around one of the pullies (no the drive pully attached to the engine). It has wrapped around the hydraulics pully and is wedged between the pully and case... it won't move at all. Any idea how to get the belt off?
As Ken said, this is what I did....Unbolted the fuse assy. and tied it out of the way, also removed the radiator over flow tank. If you see a picture of the tension mechanism you can remove it by feel. It takes a 9/16 socket and you can see the tensioner nut, it's on top and also 9/16. If there is some way to 'grip' the belt, tie it in a knot or use a 'vise-grip' you can just snatch it out by hand or come-a-long. Be patience, reinstalling is tedious, if someone can work from inside while the other is working from the back it would help. The space between the hydrostatic pulley and the housing is 'close' so don't get frustrated. Hope this helps.
If I missed something guys, please step in...
 

Fishfiles

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Feb 8, 2007
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As Ken said, this is what I did....Unbolted the fuse assy. and tied it out of the way, also removed the radiator over flow tank. If you see a picture of the tension mechanism you can remove it by feel. It takes a 9/16 socket and you can see the tensioner nut, it's on top and also 9/16. If there is some way to 'grip' the belt, tie it in a knot or use a 'vise-grip' you can just snatch it out by hand or come-a-long. Be patience, reinstalling is tedious, if someone can work from inside while the other is working from the back it would help. The space between the hydrostatic pulley and the housing is 'close' so don't get frustrated. Hope this helps.
If I missed something guys, please step in...
When going back together it is easier to have the idler pulley off and install the belt then put the idler against the belt , as far as getting it out the pulley that can be a "bear" as Tazza puts it , to get out , a good pair of diagonal side cutter and a sharp utility knife , make sure you get all the strnds out as it some stays hidden between the pulley and the pump it will eat the seal and cause a leak ------as far as how tight to put the new belt on , I have the tool thats supoose to be used but you can get by without it , it is a bar that graps the bottom of the belt , you mark the bellhousing with chalk on the top and bottom of the bar , and then hook a fish scale to the bar , then you pull like 15lbs of force , no more or less to get the bar to move to the second mark , the thing to watch out for is not too tight , if it is too lose you will know it as it will slip when you hit a pile of dirt or track hard turns , it may have to be readjusted after a few hours of use ad the belt streches out
 
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conc2steel

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Dec 30, 2007
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When going back together it is easier to have the idler pulley off and install the belt then put the idler against the belt , as far as getting it out the pulley that can be a "bear" as Tazza puts it , to get out , a good pair of diagonal side cutter and a sharp utility knife , make sure you get all the strnds out as it some stays hidden between the pulley and the pump it will eat the seal and cause a leak ------as far as how tight to put the new belt on , I have the tool thats supoose to be used but you can get by without it , it is a bar that graps the bottom of the belt , you mark the bellhousing with chalk on the top and bottom of the bar , and then hook a fish scale to the bar , then you pull like 15lbs of force , no more or less to get the bar to move to the second mark , the thing to watch out for is not too tight , if it is too lose you will know it as it will slip when you hit a pile of dirt or track hard turns , it may have to be readjusted after a few hours of use ad the belt streches out
My son and I worked on this for the better part of a weekend, to get the belt off took a torch, a chisel, a screw driver, razor knife, and 3 foot section of both 1/8" square bar and 3" X 3/16" bar. The 1st thing I did was cut the belt where I could get to it. The problem that remained was that the belt had three sections wedged between the case and the pully. I would then heat up the 1/8" bar and burn the belt (no fire), afterward heat up the 3" bar and tap the bar with a hammer and push the belt back (out of the pully/cassing). I would use the chisel in the same fashion. This sucked to say the least, but it's done. Oh yea, I had the belt under tension with a come-along so when I finally got enough of the wraps out t pulled loose.
 

skidsteer.ca

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Jan 20, 2006
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My son and I worked on this for the better part of a weekend, to get the belt off took a torch, a chisel, a screw driver, razor knife, and 3 foot section of both 1/8" square bar and 3" X 3/16" bar. The 1st thing I did was cut the belt where I could get to it. The problem that remained was that the belt had three sections wedged between the case and the pully. I would then heat up the 1/8" bar and burn the belt (no fire), afterward heat up the 3" bar and tap the bar with a hammer and push the belt back (out of the pully/cassing). I would use the chisel in the same fashion. This sucked to say the least, but it's done. Oh yea, I had the belt under tension with a come-along so when I finally got enough of the wraps out t pulled loose.
Wow!
I guess I was lucky my 773 threw the belt of the outside. My 853 I checked it and seen the back separating and put a new one on b4 it failed.
Good idea on burning it with the small bar.
Ken
 

Tazza

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Wow!
I guess I was lucky my 773 threw the belt of the outside. My 853 I checked it and seen the back separating and put a new one on b4 it failed.
Good idea on burning it with the small bar.
Ken
I thought removing the pulley would be easier and simply slide the belt pieces off. I removed the pulley on my 751 yesterday out of the machine, never ever attempt this unless its really needed!!! Even with a 5 ton hydraulic puller attached it didn't want to move.
Glad you got it removed, the hot piece of steel to burn through the belt was a pretty good idea actually. I hope to never need to do this, but good to know.
 

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