Just to clear up any confusion. There is no need to bleed the hydraulic system after a hose change or system rebuild. The air works itself out totally withing just a few cycles. Having said that dont just max out the rpm and jam a lever. Low rpm and ease into the valves. Raise or extend the cylender slowly a few times and your done. Im was an industrial maintenance man for 22 years. Certified Hyspeco hydraulic technician and expert on most hydraulic systems including pumps and equipment sizing. I also own a bobcat 763 and have changed 10 hoses and rebuilt 2 cylinders on that machine. No issues.
@zillobeast5257 Well more or less. Just activate the valve slowly a time or two and check your oil levels. And yes it will work out every drop of air. We would rebuild both telescopic cylinders on a 35 foot forklift. And hoses. 4 or 5 cycles and it was good. I have rebuilt and replaced hundreds of cylinders and thousands of feet of hose.
@@tireballastserviceofflorid7771 i have 2 questions what if you reversed the line on a lift arm? what i have was a engine rebuild and replace 2 hoses on the left lift arm. we got it running but then noticed leaks in lines we didn't touch. would tighten them leak would stop but lift and bucket would not react. but then i also didn't let it run for more than 10 seconds because of the leak i will be trying again after i tighten the union that was leaking by the hydraulic oil filter. i have a 1999 753C
@geraldsieren4135 If you crossed your lines on one side and had them regular on the other. You would notice a strong twist in the lift mechanism. All the slop in the bushings would be maxed out each time you changed directions. It would be pretty dramatic and obvious something was wrong. If the system is low enough from the leak it sucked air you will have a substantial delay before action. Especially after first firing it up. Give it 30 or 45 seconds of idling then shut it off and check your hydraulic oil. Start it back up and then begin cycling all axis slowly. If all is working properly it will clear out and function normally in a few cycles. I recently had to change a hose that feeds the cooler on the top. Absolutely insane hose to remove. Anyway I lost all the oil in the tank and pump. It didn't even bobble a little when it fired up.
The way that I understand the air is lighter than the hydraulic fluid and seeks the highest point. The hydraulic cylinders are sealed piston chambers, one end extends and the other retracts. So how can the air get back to the hydraulic reservoir? I think the air would always be trapped at the highest point. The reason that I had air in the system was because I replaced several hydraulic hoses.
Just to clear up any confusion. There is no need to bleed the hydraulic system after a hose change or system rebuild. The air works itself out totally withing just a few cycles. Having said that dont just max out the rpm and jam a lever. Low rpm and ease into the valves. Raise or extend the cylender slowly a few times and your done. Im was an industrial maintenance man for 22 years. Certified Hyspeco hydraulic technician and expert on most hydraulic systems including pumps and equipment sizing. I also own a bobcat 763 and have changed 10 hoses and rebuilt 2 cylinders on that machine. No issues.
Thanks for clearing up the confusion.
So if i install brand new bucket cylinders and hoses on a front loader i can just operate it normally and let it work itself out?
@zillobeast5257 Well more or less. Just activate the valve slowly a time or two and check your oil levels. And yes it will work out every drop of air. We would rebuild both telescopic cylinders on a 35 foot forklift. And hoses. 4 or 5 cycles and it was good. I have rebuilt and replaced hundreds of cylinders and thousands of feet of hose.
@@tireballastserviceofflorid7771 i have 2 questions what if you reversed the line on a lift arm? what i have was a engine rebuild and replace 2 hoses on the left lift arm. we got it running but then noticed leaks in lines we didn't touch. would tighten them leak would stop but lift and bucket would not react. but then i also didn't let it run for more than 10 seconds because of the leak i will be trying again after i tighten the union that was leaking by the hydraulic oil filter. i have a 1999 753C
@geraldsieren4135 If you crossed your lines on one side and had them regular on the other. You would notice a strong twist in the lift mechanism. All the slop in the bushings would be maxed out each time you changed directions. It would be pretty dramatic and obvious something was wrong. If the system is low enough from the leak it sucked air you will have a substantial delay before action. Especially after first firing it up. Give it 30 or 45 seconds of idling then shut it off and check your hydraulic oil. Start it back up and then begin cycling all axis slowly. If all is working properly it will clear out and function normally in a few cycles. I recently had to change a hose that feeds the cooler on the top. Absolutely insane hose to remove. Anyway I lost all the oil in the tank and pump. It didn't even bobble a little when it fired up.
What size Allen key are you using to crack the bleed screws with?
Allen key size is 1/4"
I have a bobcat m371 that has no bleed valves. If I was to cycle the arms and bucket would not the air work it’s way out anyway?
The way that I understand the air is lighter than the hydraulic fluid and seeks the highest point. The hydraulic cylinders are sealed piston chambers, one end extends and the other retracts. So how can the air get back to the hydraulic reservoir? I think the air would always be trapped at the highest point. The reason that I had air in the system was because I replaced several hydraulic hoses.