replacing the hydraulic/hydrostatic fluid

[little_fellow]

Hi , I`m trying to replace the hydrostatic fluid in my 773 bobcat . I`ve done everything the maintenance book tells me to do , disconnect the hoses and remove the two case drain filters . What I also did is raise the boom in the air , install the safety arm and tilt the bucket forward thinking I would get rid of more fluid with the cylinders in this position . I didn`t replace the hydraulic filter in the engine compartment because I did this about 100 hrs. ago . The problem is that I only got about 2 gallons out of this . Can anyone advise me on how to drain the rest of the fluid ?

 

[OldMachinist]

The service manual I have for a 773 says the tank holds 4 gals. and the whole system combined holds 8.5 gals. The cylinders won't drain by just raising them unless you crack open a line to let air in. Put a drain line on the aux connection and run it till the pump starts to make noise. Unless you completly dis-assemble everything and drain them you can't get all the oil out.

 

[little_fellow]

The service manual I have for a 773 says the tank holds 4 gals. and the whole system combined holds 8.5 gals. The cylinders won't drain by just raising them unless you crack open a line to let air in. Put a drain line on the aux connection and run it till the pump starts to make noise. Unless you completly dis-assemble everything and drain them you can't get all the oil out.

I will try that . Thanks for the advise .

 

[bobbie-g]

I will try that . Thanks for the advise .

Looks to me like you want all the cylinders with the rods retracted. If you think about how a cylinder is made, when the rod is extended, the entire interior is full of fluid. With the rod retracted, there is less fluid inside the cylinder because the rod is displacing fluid. So I'm going to drain mine with all the cylinder rods retracted. ---RC

 

[little_fellow]

Looks to me like you want all the cylinders with the rods retracted. If you think about how a cylinder is made, when the rod is extended, the entire interior is full of fluid. With the rod retracted, there is less fluid inside the cylinder because the rod is displacing fluid. So I'm going to drain mine with all the cylinder rods retracted. ---RC

Good point . I`ll do that also . Thanks .