No power and Slow hydraulic Lift and tilt 751

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Unos

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Nov 16, 2007
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Used my Bobcat 751 to transplant some tree's wasn't to hard on the machine and i notice i kept loosing more and more power. checked the fluids, filter is new, crankcase filters are 4 months old, Ive got joysticks on the machine so they can't be out of adjustment and the pump isn't leaking any oil. Any idea's will be appriciated. thanks
 

skidsteer.ca

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Check the big belt that drive the pumps sometime they get loose and slip under high loades
Ken
 
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Unos

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Nov 16, 2007
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Check the big belt that drive the pumps sometime they get loose and slip under high loades
Ken
I wish that was the problem but it has all new belts did those last month. It has no hydraulic power under no load conditions, i have to speed the motor up just to get it to get the arms to pick up.
 

Tazza

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I wish that was the problem but it has all new belts did those last month. It has no hydraulic power under no load conditions, i have to speed the motor up just to get it to get the arms to pick up.
You may have new belts but they do stretch. It may be an idea to check the tensioner if it has one fitted if not check the tension of the belt. A few people in here have been caught by this before. Do you have the same problem with driving power? load the hydraulics down and see how your drive is, if you have no power there too i would say belt for sure.
 
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Unos

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You may have new belts but they do stretch. It may be an idea to check the tensioner if it has one fitted if not check the tension of the belt. A few people in here have been caught by this before. Do you have the same problem with driving power? load the hydraulics down and see how your drive is, if you have no power there too i would say belt for sure.
no it has plenty of power going foward and back just doesn't want to pick up. i checked the tensioner it is at 1:00 like the book says so im assuming that isn't the problem thanks
 

Tazza

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no it has plenty of power going foward and back just doesn't want to pick up. i checked the tensioner it is at 1:00 like the book says so im assuming that isn't the problem thanks
Did the engine seem to bog down a bit at all? The only other thing i could think of is that the axu hydraulics were being engaged somehow. If they are on your oil will be going over the relief and causing very little power to lift/tilt. Not sure how this would happen but the only other option i have.....
 

skidboy

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Jan 3, 2007
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Did the engine seem to bog down a bit at all? The only other thing i could think of is that the axu hydraulics were being engaged somehow. If they are on your oil will be going over the relief and causing very little power to lift/tilt. Not sure how this would happen but the only other option i have.....
The pointer should be at 3 o,clock ,might want to check that.
 

skidsteer.ca

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ok put the pointer at 3 o'clock no luck there, do you think it could be the pump??? or trash in the system???
Should'nt be your aux hyd, they should shut off with the key every time, but try kicking them on and off to see if anthing acts differently. You shoud be able to here the motor labour when you move the rh steering lever thumb switch off of center either left or right. It is possible they spool has stuck on, not to likely though.
Does it seem to get weaker as it warms up? That is a sure sign of a hydraulic pump or other component problem. As the oil warms and gets thin the max pressure it can achive gets lower and lower. The pressure escapes though the worn areas.
You can hook a pressure guage to your aux couplers and see what pressure it can achive. should be somewhere around 2250 to 2500 psi. Check your manual for system relief valve pressure spec.
The best way to check you pump is to hook the machine to a flow meter and measure the flow (gpm) at various pressures. If the flow takes a dive as the flow meter increases the pressure, then the pump is likely toast.
Ken
 

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