Hi All, I am new to this field. I have a Bobcat 753B model early model no electronics. When driving forward the motor stalls, this has just started to happen. When I restart, the motor is under load and is struggling to start, it takes a number of attempts to get it started, eventually the hydraulics seam to bleed off and the motor will start. I can drive for a minute or two then it stalls again. Repeating the process till I can get it back to the shed. A few days later I can take it out again and it will run for a 3/4 hour then stall. etc etc. I have changed all the filters and both case drain filters, also changed the oil and there is a small hydraulic leak ( cleanish oil ) leaking from under machine about a 1/2 cup over 2 weeks. Would anyone have come across this problem before, any advice would be helpful.
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bobbie-g
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Doesn't sound like the aux hydraulics are stuck on, but make sure they aren't. Also, does it act this way in reverse also? And welcome to the forum! ---Bobbie-G
I have not had this happen while reversing. Only notice when driving forward or digging a bucket full of dirt.
bobbie-g
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I think it's not uncommon for the motor to bog down when digging a full bucket of dirt. Mine does. When you have the bogging down issue when driving fwd, does the engine go back to running normal when you stop moving fwd and put the joysticks back in neutral (I'm assuming not since you have trouble starting it)? And if you then immediately try to back up, do you get the bogging down? Just tying to understand the nature of the problem. Something is obviously putting a load on the engine. Have you checked out the mechanical linkages under the cab? To lift the cab, there are two 3/4" nuts that hold the front. Remove those two nuts plus the square "washers" under them and the front of the cab will lift; hinged at the back behind your shoulders. Lifting the cab will then crush anything you have stowed just behind your window (exhaust cover can, fire extinguisher, tow straps, lunch box, etc). If you haven't had the cab up, it may take a firm tug to break it loose, but it'll come. Sometimes the lines rust and get attached to the insulation under the seat.
No its not the digging that stalls the motor. It loads up digging but that is normal. This issue happens sometimes digging but also when driving along. I have the cab open and access to the valves and controls, also have cleaned the hole machine inside and out to be able to work on it. Currently have the bobcat on stands and all covers off and cab up, so that I can have a good look at whats going on. The drive motors run well while up on stands,I have run them for about half an hour forward and reverse. I have noticed a few axle seals leaking, I will replace them. I changed the chain case oil about 12 months ago, when I did a major service. This problem may be a relief valve or something similar but where and how do I check.I think it's not uncommon for the motor to bog down when digging a full bucket of dirt. Mine does. When you have the bogging down issue when driving fwd, does the engine go back to running normal when you stop moving fwd and put the joysticks back in neutral (I'm assuming not since you have trouble starting it)? And if you then immediately try to back up, do you get the bogging down? Just tying to understand the nature of the problem. Something is obviously putting a load on the engine. Have you checked out the mechanical linkages under the cab? To lift the cab, there are two 3/4" nuts that hold the front. Remove those two nuts plus the square "washers" under them and the front of the cab will lift; hinged at the back behind your shoulders. Lifting the cab will then crush anything you have stowed just behind your window (exhaust cover can, fire extinguisher, tow straps, lunch box, etc). If you haven't had the cab up, it may take a firm tug to break it loose, but it'll come. Sometimes the lines rust and get attached to the insulation under the seat.
bobbie-g
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Looks like you've done a great job in going as far as you have, and have thought things thru very well. You've passed me in what to do next (assuming all the mechanical linkages seem to look and work OK). Must be very frustrating that it won't mess up while up on jack stands so you can see what's going on. Let's see if some of the smart guys here on the forum will jump in at this point.
---Bobbie-G