I HAVE A 1986 843 BOBCAT THE HYRDAULIC MAKING A WHINING NOISE AT LOWER ENGINE SPEED AT FASTER SPEED NOT AS NOTICABLE, I HAVE CHANGE THE FILTER AND FLUIDS TWICE, THE HYRADULIC PUMP CRACKED ON ME, NEW PUMP INSTALLED STILL HAVE WHINING NOISE, USING ORIGINAL BOBCAT FLUID, MACHINE RUNS FINE, HYDRAULIC SOME TIMES OVERFLOWS OUT OF THE FILL CAP, I USE MACHINE MOSTLY IN SNOW, DOESNT MATTER IF MACHINE IS IN GARAGE OR OUTSIDE WHEN STARTED COLD, GARAGE IS 70 DEGRESS. I HAVE NO CLUE ABOUT THE HYRADULIC SYSTEM, IM A NISSAN MASTER TECH NOT AT BOCAT TECH LOL... ANY HELP???? WHAT SHOULD I LOOK FOR? TESTS? THANKS PAUL
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Paul, first off turn caps lock off.
Has it always made this noise? its normal for the hydrostatics to be rather loud at low engine speed, you should be running 1/2 to 3/4 throttle when using it.
You mention oil comes out of the filling cap, you haven't over filled it by any chance have you? Is the oil foamy?
Has it always made this noise? its normal for the hydrostatics to be rather loud at low engine speed, you should be running 1/2 to 3/4 throttle when using it.
You mention oil comes out of the filling cap, you haven't over filled it by any chance have you? Is the oil foamy?
Sorry about caps., noise is still present at higher speed just not as loud. oil level checked with engine running or shut off? oil looks foamy, at 1/2 throttle the hydrostatics still make noise at 3/4 not that noticeble.
OldMachinist
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If the oil is foamy you're sucking air into the system somewhere or you have a restriction causing cavitation. I'm not sure if your machine has a case drain filter(it depends on your serial number) but if it does it could be clogged.
If it has a case drain filter where would it be? 1986 843 isuzu engine.
Case drain filters if fitted are located on the small hoses from the drive motors. They should look like alloy cylinders, about 3" long.
Do you have any oil leaks?
You check the oil level when its stopped and on flat ground.
How long ago did you change out the pump? i wonder if its still got air in the system causing the foaming.....
i ran it about 2 hours at idle after i installed the pump.
OldMachinist
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You need to drive it around at half throttle while raising, lowering and tilting the bucket for about 15 mins. to work the air out of the system. Don't run the cylinders to the stops as it will cause more cavitation with air in the system. Let it sit overnight, check the fluid level and repeat the next day, most of the air should be out. If after doing that the oil still foams I'd be looking for a suction leak. Sometimes a leak on the suction side won't drip much oil so you may not notice a puddle. Wipe everything down around the suction line from the tank to the pump and look for small overnight drips.
Thanks for all your help guys. ill check it out and report back.