I had my 721 in the local VoTech last year for new axle seals, and loads of other small stuff................... They did a great job.............................. I had them change the hydraulic oil as well. After talking with Bobcat dealers and others I was assured that regular 10-30W motor oil was the fluid of choice. So I had TropArtic SemiSynthetic 10-30W installed. ................ It seems to rund fine but when cold it takes a minute for the hydraulics to work, like it needs to build up pressure. After that, it's great............... My questions............ is this normal???.......... Is motor oil OK instead of hydraulic fluid?? Bobcat claims that is what is in the new machines....
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thetool
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That oil is fine. As far as normal for your machine to "build pressure" or whatever it's doing it may just be because you have an older machine there and the pump is on the downside of life. Pay attention to noises, and try to notice if it gets worse all of a sudden.
I assume you changed the hydraulic filter as well as the oil.
I assume you changed the hydraulic filter as well as the oil.
All filters were changed.......... What type of noise?
thetool
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It's hard to explain-sort of like a grinding gurgling whiney growl. Does your boom chatter and jump when you raise it? Do you have foamy oil?
Does it only last for a minute then completely go away?
sledesigns
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From my own observation pouring 10-30 motor oil or hydraulic oil in 0 degree temps, the hydro oil seems much thinner, less temperature sensitive. Could the motor oil be thicker when colder and cavitate for a bit before moving and warming up?
I would have said it just needs to warm up a little, the colder it gets the thicker it gets. Standard hydraulic oil is too thin in hot weather, motor oil is fine. If it runs well in the hot time of the year I'd suspect the pumps are ok as the thicker the oil is the less problems you notice from worn parts. When its thin it seems to by-pass the spaces generated by wear.
siduramaxde
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If 10w 30 is too thick when cold why not go to a 5w 30. Isn't the 5w 30 supposed to act like a 5w oil when it's cold but act like a 30w oil when it's warm? If this is true the oil would be thinner when it's cold out but will also be fine in the summer.
"If 10w 30 is too thick when cold why not go to a 5w 30. "...... I went with a semi-synthetic for a little better cold performance. Changing out nearly 20 gallons of oil is a bit spendy if I have to do it every winter..................... I'll keep an eye on it, if warm weather ever comes -17F right now!!
Does it act like that even if you start it and let it idle for at least 5 minutes in cold weather? If it is down to 0 or so it should be let to warm up a little before trying to work it.
sterlclan
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Im getting older too and I dont move so good when cold, let it sit and warm up a little, 10 30 is ok just add a little time and listen to the pumps if they start to make more noise worry about it then.....Jeff
Is rebuilding pumps a do it yourselfer?? I have good mechanic skills and plenty of tools.......... Just never worked on hydraulics................... And yes, if I let is sit for a minute or two it is fine.
sterlclan
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I did my own pumps and drives...wasn't too bad....Jeff
How spendy are the parts???? Are there lots of "special tools" you have to buy??............ Thanks again for a great web site!!
There are no special tools needed.
It all depends on how far you want to go. The drive pumps are a little more complex but not rocket science. The hydraulic pump is very simple.
I'm not sure what setup your pump has, but does it have a square block on the hydraulic pump with 3 hoses on the left? If so, remove the middle hose and fitting from the block. There is a hidden filter, clean or replace it.
You can get kits for the hydraulic pump from http://www.loaderpartssource.com/ it will consist of a new cam ring, new rotor and vanes plus a few O rings. This will make your hydraulic pump run like new. Over time the vanes will wear and the cam ring can get chatter marks that make it not work as well as it once did.
Start with that hidden filter if its fitted.
i have a new machine and its the same they ALL need to warm up to work properly.if you love your machine you would let it warm up
