I have a 331 Bobcat about a 1998 I am having a little trouble with and was hoping someone could point me in the right direction as what might be wrong with it. I am having trouble with a slow track drive on the left side, it's been acting up for a couple years now, and I have only noticed it toward the end of the season. Last winter I drained and refilled final drive gears with oil, and couldn't find anything wrong, but suspected final drive motors. I worked it last year without a problem until loading it on the trailer for the last time at the end of the season. Yesterday I unloaded it after sitting since last job to check things out. What I found out is if you curl the bucket at the same time as trying to travel the left track will slow down or stop, depending on how much you pull joy stick to curl bucket. I probably had one hand on that joy stick and one hand on both drive levers when I had the troubles. Last fall was only the 3rd time I had this trouble and each time it never lasted long. I don't use the machine daily, just a few septic repairs and about 4 septic installs a year. Is this problem something to worry about, and what could be the problem? Thank you, Woody
I always say follow the oil and you'll find your problem. Of course when you don't it's an electrical problem I'd recommend testing the pressures on your machine. Start at the pump. Then at the main control valve. If consistent flow and pressure, then check at the travel motor. You should be able to isolate where the problem is from doing this. From your description of utlizing multiple functions and having the track slow down I'd say the hydraulic pump is not performing optimally and not able to hold consistent pressure.
Hi woody, Does all your other digger functions work properly, nothing else is slower than it used to be? If so, you probably have a drive motor problem. You can sort of test a drive motor by checking the case drain on the motor. The case drain drains off internal leakage of the motor, which on a good motor is just a small amount of oil/flow. If a motor craps out inside, the amount of oil coming out the case drain fitting increases, indicating a bad motor. Lift your machine off the ground with blade and bucket (do not get body parts under tracks when doing this), disconnect the small hose that goes to the suspect drive motor, put an appropriate plug in fitting on hose disconnected from motor, leave fitting on motor open. Operate the track of that motor. A small amount of oil should come out of fitting. A good flow of oil coming from fitting would indicate bad motor. To verify, you could remove both motors and switch them, see if the problem moves to the opposite track.
Another quick telltale sign is to cut open the filter and check for brass. It does sound as though you may have a bad motor, typically if your pump is failing both motors or depending on the unit the boom functions will all be affected. If the case drain is within spec(a dealer can provide specs for that) and the filter is not contaminated with brass or metal you can check your schematic for common valves (flow dividers,cross-over relief), not sure what all that unit has in its drive circiuts it has been about 10 years since I put a wrench to a bobcat exc. I hope you post what you find the problem to be.
Thanks for the replies guys, I will preform some of the tests for pump and track motor in a few weeks. Right now I am in the middle of a kitchen overhaul. After your replies, I was curious so went out this morning to check a few things with the mini. I can use any of the other hydraulics as I am traveling forward or backwards and have no problem. The only time I have the problem is if I am curling or uncurling the bucket. It will stop the track completely if I curl the bucket to the limit as I continue to hold the joystick control to curl bucket. I also did this with the track in the air and same thing happened. When I am pulling back on the track lever, track turning, and stop the track with bucket curled, then let go of joystick that is curling bucket, but still have track lever pulled back, the track won't start until I release track lever and pull it back again. I hope I explained that ok. But it's just odd to me that it happens this way. I don't have any other troubles with the track other then what I explained. All hydraulics are as strong as ever. I guess the first thing I will do is remove the filter and cut it open to inspect it.
Any luck on the mini?
Slow/Weak drive motor I too am having the same issue with one of my track drive motors. It is slow and weak all the time. It is a Kubota KX121-2. Swapped pump outlet lines = problem stayed on same side. Checked pressure of FWD and REV on both motors (@ motor) good pressure aprox 3000psi. I checked the case draines on both motors with the tracks on the ground and under load. Normal motor = slight leakage. Slow/Weak motor = large amount of oil discharge. I'm going for the drive motor. I am researching on how to overhaul the "hydraulic" side of these motors, common wear items and how too's. Is there overhaul / seal kits available for these motors?
TCM - you are on the right path. Excessive case drain does point towards the motor. This particular drive is notorious for the motor shaft and sun gear wearing abnormally causing the motor to also wear out prematurely. Send me a private message, I can help you. Best for me to communicate via email. I don't get here as often as I'd like to anymore.
I can to send to send a privaye message, a "you are not authorized" message pops up. Is there a moderator around who can point me in the right direction? Asfor the motor, I have swapped the motors left to right and the problem follows the motor so I removed the Slow/weak motor from the machine. Now on the work bench I have seperated the valve assy from the body and I am looking at the pistion/swashplate assy and the valve body assy. The swashplate and pistion block assy look like new everywhere including the swashplate/pistons mating surface. I am going to dissasemble the valve block assy with hopes I come across some bad seals letting fluid bypass to the case drain. If someone can give some pointers, ie. what to look fo,r a good place to buy seals that would be great. Thanks
Welcome to the forum TCM. You don't have access to all the forum features as long as you're a probationary member. You need to get 3 posts in to change your status to Junior Member, then you can send PM to other members.
Thanks for your help folks.
I too, have a 331 that is doing the same thing I bought a used 331x to piddle with and build a seawall. The outfit I bought it from advertised "recent final drive work totaling $7000" so I figure the final drives must be OK (maybe not). The high speed drive has never worked but the switch is disconnected and I have not gotten to that problem yet. The machine worked fine for a while, had 10,000 hydraulic leaks and after renting hydraulic oil for about 2 months I finally got all the hoses replaced and the leaks stopped. The drive motor hoses were especially a lot of fun replacing the route they picked. After all the leaks were stopped the drive motors started giving me trouble, they did not stop all at once. Left side was weak at first now both have almost completely stopped working. We have checked the the pressures out on the pump, first stage pressures are from 2200-2700, second stage pressures that operate the travel motors and bucket curl range 500-1100. Bucket curl will operate but very slow, if you try to operate bucket curl with travel motors engaged the joystick becomes very stiff. I have talked to bobcat people and get a different answer every time. I'm trying to figure out if the pump is bad, the drive motors or the pressure relief device. I have worked on farm equipment, tractors and backhoes but never anything this complex and I think I'm in over my head. I don't mind spending money if I know it will fix the problem but I don't want to just start replacing $2000 to $4000 parts as this will get very costly very quickly. Anybody have any suggestions
Look at 2nd post in this thread. I have to ask...Have you changed the hydraulic filters and know that you have a clean hydraulic system? Have you checked pressures at the travel motors? From what you've described my vote is the pump needs to be rebuilt. Sounds like it may not be holding the pressure that it is building up.
yes, system has been completely drained, new filters and new fluid after all leaks were stopped. I have not checked the pressures at the travel motors yet (not sure I know what it needs to be-I have not found that in the book yet). It is the 2nd stage of the pump that is showing weak pressures ....... according to the maintenance manual it could be one of three pressure relief valves. I live in Shreveport Louisiana, only one company around here that works on final drives/travel motor and this type hydraulic pump but they say they can't test under load so I'm right back to throwing $$ at a problem that I'm not sure they are gonna fix. Any ideas on who might work on this stuff in my area ???
finaldriveparts.com - found these guys on youtube. I'm about ready to send in my drive motor, ther track will stop unexpectedly, the pressures are normal. I'm going to cut open the old filter and try to hunt down brass. GL woody!
I've got a two speed Bobcat, when I try to pivot the tracks in high gear it stalls. It turns fine in low speed. Traveling is done in high speed when not trying to turn. Is this normal ?