I have a 90's Bobcat 440b and has been a great little machine but recently it started leaking oil out of the top of the chaincase. Oil comes out of the top past the seal. I have already put in new seal kits and O rings on both drive motors. And the problem persists. Anyone have any ideas? I really need to get this machine going. Thanks in advance!
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little_fellow
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Might be some water got in as condensation or other means and causes it to overflow.
7LBSSMALLIE
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dont bolt motors up, hang from hoses . over a drain pan. rules out motors.
7LBSSMALLIE
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check for cracks around bolt holes as well. drill a hole, at stopping point, grind and weld.
7LBSSMALLIE
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hint if can can run non ethanol gas do so, will extend eng life
little_fellow
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My owners manual for 773 Bobcat says chain case oil= 9 gallons oil. Are you over filling?
little_fellow
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Should be a breather hole on top of the tank. Maybe it's plugged?
brdgbldr
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Are you having to refill the oil reservoir? If you are, then the motors are leaking into the chain case. Even though you just replaced the seals does not mean that the seals did not blow out again. If the system builds up too much pressure because of other issues the new seals may have blown out.
If you have not had to refill the oil reservoir, then the problem is just an overfilled chain case. The oil in the chain case should be high enough, on level ground, that when you put your finger in the inspection hole (at the front of the chain case) to the first knuckle the tip of your finger gets wet. if you put more oil in than this, just the sloshing of the oil can cause it to come out the top of the chain case.
When I recently resealed the motors I sucked out the old oil and replaced it with new oil. I tried to follow the Manual to the letter. I will inspect to see if I happened to over fill it.
What could be the cause of pressure build up in the system? And how would I check? This is a smaller, older machine and there are no in-line hydraulic filters for me to clean out and I just recently replaced the Primary Hydraulic filter.
I will have to check for that and see.! Thank you
I just added fluid and I noticed that it is low again.
brdgbldr
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Pressure build up could be caused by a bad relief valve or something clogging the system.
This is one of the reasons that they added filters to the hydrostatic systems in later machines.
Someone just posted on here that they had replaced some hoses and then started having issues. Ended up that one of the brand new hoses was crimped wrong, blocking the fluid flow.
if you are adding to hyd oil and the chain case is over fulling look at what is connecting the two ie drive motor seals.
I deal with this regularly and find that most often the Motor Carrier Seals are leaking. They are relatively inexpensive but hard to install. There are videos of people changing them but they leave out an important step. That step is getting them to stretch over the shaft going into the chain case. What I always do is use 2" pvc pipe and build up a taper on the pvc to help transition the seal from the pipe to the shaft. It will just slide up and on if the build up is just right. Otherwise the seal will roll the lip over and leak under pressure.
