Just got a new to me 753 no boss just the bics(sp).... was working fine and then..............nothing...the engine runs fine, throttles up starts etc..... no hydraulic anything.... there is the clicks when the buttons are pushed of the restraint is put down, when the parking brake is taken off, the lights on the bic are all green and all other gauges and indications are normal,.... the only thing noticeable is that in the hydraulic tank there seems to be a surge when the machine is shut down, didn't notice this before. It does sound like a surge of air, almost like there is airlock in the supply side of the pump, and then when the pump is shut off (engine) there is a rush of air (assuming) into the tank. the engine was out to fix a leak in the fuel system just before it was delivered to me... as I said it is new to me so there has not been the time to get the manuals out to me yet.... but will be ordering them tomorrow..... thanks for any help.... p.s. I have a fair idea which is the box end and which is the open end.........
Help Support SkidSteer Forum:
I would check the tension and condition of the pump drive belt which is behind the plastic cover over the bell housing on side of the battery and held on wih three spring clips , there should be an arrow at the bottom of the roller of the adjuster , which really is betwee the roller and the mounting plate , the pointer should point at 3 o clock position if properly adjusted , the decal on the inside of the back door will show you how to do the adjustment ,a lot of times the pointer is broke and doesn't work and it is possible that there is no pointer on yours depending on age of machine , older ones were adjusted with a Bobct bar and a fish scale and pulled to 15 pounds in the wide of the bars travel , but you can get by without it --------I think chances are pretty good the belt is your problem
It sounds like you may have an air lock there, but the oil tank joines direct to the hydraulic pump so it should have no problems with priming. Do you hear any noises when you try to lift or tilt? what about enabling your aux hydraulics and using the finger switches?
it does sound like an air lock but as you said usually the tank goes to the inlet of the pump and unless the hose has collapsed there should always be oil to the pump, but am getting air back into the reservoir when the machine is not operating by pushing the controls, you hear the gurgles in the tank.... as far as the response in the hydraulics, there is no load on the engine no squel of belts or passing of fluid as when the parking brakes are on , did try the aux switch earlier and again no noises, although nothing is hooked to the couplers... thanks for your time.....
This thing stopped dead and will not move or lift ..... can I see the reservoir and hose to the pump if the cab is tilted??????
Thanks for your suggestion... it is night now so will try that in the am.... but why would it just stop, did have aquick look in there and it seems that the belt was still there and turning as we would also lose the cooling fan and beleive that was still running when i checked, my concern is that it just stopped... no belt squelling or any sign like that.... but right now am looking at all possibilities, again thanks for your time and suggestions
Well , the reason I said belt is from seeing it happen alot that a total lost of function is high percentage the drive belt , the drive belt spins the pulley on the pump , the same pulley powers the blower fan so true if the belt where totally off or so loose the blower wouldn't be turning , but I have seen the belt turn the pump pulley but was not tight enough to make the machine function , -------------just another wild guess from reading your other post -----I think you are out off oil in your tank and you don't realize it because no oil is leaking out the machine , the oil is all in the right side belly pan and is trapped in there from mud blocking up the drain hole , the oil is in there because the main pressure hose from the gear pump to the controll value is blow out from rubbing where it contacts the bottom of the belly pan and the gurgaling of air you are hearing is air being pumped thru the hose and bubbling up thru the oil in the bottom of the pan
Fishfiles makes a good point, don't overlook the drive belt. Even though it looks like its ok, when under load it can slip.
I just wonder if its possible that the shaft between the pump and pulley is broken. The gurgling is possibly engine vibrations dis-lodging air bubbles that makes it seem like the hydraulic pump is working but is not?
I assume it was all ok before the engine was pulled? as if it was, the shaft between pump sections should be fine, there is no reason for there to be an issue.
I hope its something simple!
Right where it stopped it has a right low list of 4 to 5 degrees (to the side of the filler of the hyd reservoir) the tank is full enough that when you pull the dipstick oil is draining from the tank, and will check the belt in the am, thanks again.....
firstly thank you to all that helped, including those in bobcat of central manitoba..... the problem was a peice of clear plastic sight gauge about 14 inches long with an id of 3/4"....... still have some fishing to do and will drain and perhaps remove the tank for a real good look..... was talking to bobcat parts and told them of my dilema and that all appeared well on the outside... there was talk of sheared shafts internal of the hydrostat pump.... basically $$$$$$$$$$$$..... thanks again
Really don't understand your answer of what the problems was , a 14" piece of sight glass what is that all about ????????????? must be Great North thinge , ahhhhhhhh!!!!!!
perhaps a farmer thing..... once would have been a peice of clear plastic hose.... like the kind that may be plumbed into the top and bottom of a tank to indicate the level in the resevoir
Jeffscarstrucks
Well-known member
- Joined
- Nov 24, 2007
- Messages
- 92
Maybe a piece of tubing used as an extension on a funnel or container? JEFF
could of been , it was great that it was the problem and not the hydro, but would have been better if it had not been in there at all. There is always the stress of buying something used and wondering what will break or when it will break, it does take a little while to get the trust in any machine. hopefully all will be good now, played with it a little more yesterday and so far so good, will try and get the backhoe attachment on today and try that out, doesn't have the bob tach on the hoe so will manufacture one.
So maybe now it makes sense to me , I get it that a piece of tubing was inside the tank from a funnel extension incident gone bad in th past and possibly found it's way to the throat of the fitting at the tank bottom , when suction occurred it placed it's self right over the hole and sucked air from a higher level in the tank ---- classic Murphy's Law
sorry man, thought it was understood what had happened, again thanks for the insight earlier.....
