Hi guys, My Bobcat 763 is using hydraulic oil. I found a couple of leaks...1 was a seal and 2 was a cracked hose. Both are now repaired and no more visible leaks under the cab. I filled machine with oil and ran bobcat doing some grass slashing with my slasher for about half an hour this morning when all of a sudden I lost hydraulics...it was out of hydraulic oil again. I checked under cab...no leaks, checked under belly plate of machine, no leaks, checked in engine bay area, no leaks. The hoses and drive motor on slasher are not leaking either. I am stumped...where could the hydraulic oil have gone? Is it possible for the oil to leak from the track drive motors into the drive chain box under the cab?
Yep, pull the plug at the front of the machine, that's the oil level for the chain case. If it dumps oil out of that oil level hole then that would be your hydraulic oil leak.
Sorry, I should have said, remove the bucket/attachment from the loader, raise the loader arms and install the safety prop, then remove the plug at the front of the machine.
Yes, motor shaft seals can fail and dump oil into the chain case. The link below may help, there are manuals online available to a degree. Pull the check plug for the chain case, make sure you have a large drain pan under it. https://www.slideshare.net/hjdkmsme...-manual-sn-512212001-thru-512249999-114037985
Bad Willie, bad, bad Willie! LOL. Safety third as Mike sez.
Hey, I did quickly clarify myself. To check that level plug you have to raise the loader arms to get good access. The practice I developed long ago on those machines, can't preach it enough, is to remove the attachment. It's a quick couple, get that weight off and toss it before you raise the arms and prop it.
Excellent advice, the newer machines all should have safety prop devices in place yes? Never hurts to remind folks those are NOT designed to hold a loaded bucket or grapple up in the air, lol.
Bobcat machines have had incorporated safety props since I know at least the C series machine. And the prop is more than adequate to support the arms and bucket. But me, it's a quick attach, toss the dang bucket, no sense having that hanging over me when it's so easy to toss it.
From what I've heard if the drive motor is leaking, it often has to be replaced. There's usually a problem in the motor that takes the seals out but maybe you'll get lucky. Not sure if your machine has case drain filters but would be good to check.
A 763 is an aged machine. Yes, they had case drain filters, would be something worth giving a look at, see if there's debris in there. Filling chain case with oil on a Bobcat is typically a failed drive motor putting excessive internal leakage pressure on the seals in the motor carrier, excessive debris in case drain filter would indicate that. But one could get lucky, being an aged machine, could simply be the seal in the motor carrier has simply gone south. Checking the case drain filter would be a good place to start.
Thanks guys, I thought that was the likely problem...I could see any other place where 30litres of hydraulic oil could "hide". I assume now the case is overfull, when I remove drive motors, oil will leak out of the chain case sides? Also, is there an alternative brand for the pair of inline return filters under the cab, i can source other than genuine...bobcat parts are a rip-off!(anyone know the filter specs?)
You might have bigger problems than a couple filters. If you need a need a new wheel motor could be a $2000+ repair.
Just pull the check plug and drain the oil level down to where it should be before you start tearing things apart. Get the Bobcat part number run it through the Donaldson (my recommendation) or Fleetguard or WIX cross reference web pages, they'll have filters for it.
The case drain filters for the drive motors are sintered bronze filters. They're typically washable with solvent unless they're wasted with debris from a failed motor, which then you would replace them along with replacing the motor. Removing the two filters and and disassembling them will indicate which motor is bad if it's filled one with debris
Hi guys, Too much back pressure on rhs inline return filters has caused the rhs drive motor inner shaft seal to blow inwards (see photos). I am assuming my only option is to go in through access panel umder cab into chain drive area and remove the bolts that hold the drive motor mounting housing to pull this big seal and replace it? Ps i tried sharing from Google drive...not sure if it worked from my phone so I attached images as well
Not seeing the pictures, but yep I think so. Only question is, is the motor bypassing excessively internally so that it will blow out the new seal in short order?
Removing linkages etc to gain access to the panel
Access panel is now ready to remove
This is not going to be easy...that housing also holds bearings for the chain primary drive shaft.
That looks ugly, have you replaced the motor shaft seal? I'm not 100% sure that inner seal isn't supposed to keep gear oil from coming out?
I haven't pulled motor apart yet. Getting the housing out in order to sort out the main shaft seal has turned out to be a nightmare. The bottom rear most bolt is almost impossible to get at...and even though I 0ulled the front drain plug, there is still 3-4 inches of chain case oil in the machine. I am going to purchase a 15/16" ratchet/geared ring spanner...its the only thing that will go in at the right angle of rotation in order to undo this last bolt (normal ring spanner either hits the chain case opening border or, hits the drive sprockets). Socket hits chains and brake plates! I would take a photo of this but with oil still in there, photo is pointless. Also need to syphon out the remain oil...which I estimate is at least 10 litres. How do they normally get out all the oil...as it is I would have to lift the back ofthe machine up at least 3 feet in the air to drain it through the front bung...that's ridiculous!
Should be a drain plug on the bottom of the case.
There's a drain plug at the rear of the chain case, access is under the belly of the machine, not that easy but it's there. Failed motor carrier seal is typically caused by failed or failing drive motor, too much internal leakage which puts pressure on the motor carrier seal and pops it. It can be caused by aged motor carrier seal, case drain filters give somewhat an indication of motor condition, filter full of debris for sure indicates failing/failed motor, clean case drain filter, mmm, could be just an aged and failed motor carrier seal. Removing that motor carrier is a real task. It's been years since I've worked on one of those so the cobwebs in my head are excessively thick, and I could be wrong, but seems I've replaced that motor carrier seal with the motor carrier still mounted. Been too many years for me to confirm that though.
How do they normally get out all the oil... willie59 could tell you about the SUCK BUCKET! HeavyEquipmentForums Joe H
I have done that, jack the rear of the machine up, drain all I can from the front fill/level plug, then get the remaining oil with the suck bucket.