Hello, I recently picked up a 440 to have around my home. The possibilities seem endless with this little guy. I bought it from a guy that clearly didn't seem to know much about it. It has the Kohler17 engine that I tuned up and adjusted the governor, and it seems to be running pretty well. I had plans of doing a repower with one of the 22HP predator engines, but will wait for now. This is my first skid steer and I don't have a ton of experience with hydraulics. Everything "worked" when I bought it, and I didn't see any real leaks coming from it. The lift cylinders seemed to have a slight studder/pause when I raise them up, that seemed like some air in the lines to me. Yesterday, I was able to finally get it outside and give it a little workout for 30-40 minutes moving some chunks of wood/stumps, etc. I was generally pretty happy with it. When I was all done and putting it away in the garage, I cycled the lift and tilt hydros a few more times to see if maybe I did have air in the system. When I shut down the engine and used the pedals to release pressure, it almost sounded like some running water coming from the right side. I hopped out and noticed a bunch of oil leaking down the left side of the machine. Bummer. I figured that I had blown my first hose. (the hour meter shows 1508 hours and most hoses appear to be original) I've since spent quit a bit of time trying to trace back the leak. It seemed like a few quarts of oil at least, so surely it would be easy to spot the leak. No such luck. Naturally, the inside has not been cleaned in my years (or ever), so that makes it a bit more difficult, but I still could not spot anything. Originally, the oil level was little bit above the top mark, and after this leak it was closer to the bottom mark. So I decided to fire it back up and see if I could get it to leak more and again trace it back to the source. The lift still seemed like it had air in the system, but did function OK. I shut it off after a few minutes, but no leaks this time! I've been reading many posts on here and trying to study the service manual to understand how this machine operates as much as I can. The one suspicious thing I've noticed both times is that the reservoir appears to have TONS of air bubbles in it after I shut the machine down. This is now making me think that I have an air leak between the tank and hydraulic pump (or the pump itself), and that the fluid level raised up so much with all the air bubbles in it, that it just overflowed out of the tank. Does anyone have any other suggestions or ideas to try? One of the lift cylinders seems to seep out a bit of oil, but could air get sucked into the system any other way? Should there be bubbles at all in the hydro tank? I figured, even an air leak between the tank and pump would still seep out oil when the machine is not running? Thanks again for ant tips or advice. I'm loving this little guy and will be super happy when I get this particular issue resolved. PS, I forgot to add, that I have not changed the hydro oil or filter. I was going to try that this weekend to see if it makes any difference at all...or at least put a new filter on. I just don't know what oil is currently in there, and if I add something different, will it make a big difference. At only 4 gallon capacity, it seems like it might be worth it to just drain and replace.
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Good to hear you have it running pretty well.
As for the leaks, it is possible that your pump is cavetating causing the oil to foam up and over filling the oil tank, i'd expect it to not pour lots out as there should be a fabric material on the breather cap that will help prevent the oil just pouring out.
Not sure if this model has a suction line filter or not, but if it's plugged, it will foam the oil too.
A bad pump can cause this issue too.
As for the leaks, it is possible that your pump is cavetating causing the oil to foam up and over filling the oil tank, i'd expect it to not pour lots out as there should be a fabric material on the breather cap that will help prevent the oil just pouring out.
Not sure if this model has a suction line filter or not, but if it's plugged, it will foam the oil too.
A bad pump can cause this issue too.
Thanks for the tips. How does the pump cavitate? I guess the air has to be getting in somehow. I guess I'll try changing the filter and maybe oil to see if that makes any difference. If I can't find any air leaks, maybe I'll have to pull the pump off for a good inspection. Those should be rebuildable, right?
Pumps can cavetate from wear, air being drawn in or a restriction on the inlet.
If it's a gear pump, and it's bad, it will need replacing, you can't repair them. If it's a vane pump, you can repair them with a new cartridge.
I'd start with the simple stuff first, filters. I don't know if this model has a suction line filter or not, but if it does, make sure it's nice and clean.
OK The leak may well be from the hydraulic filter . I am going on what I know about a 500 I think the 440 is the same . The filter is under your feet . Raise the front of the machine and block or run the front wheels up on car ramps . Then you pull the floor boards . you have to unhook 1 control rod . This part is important . There is a square O Ring on the filter base that is not included in a new filter Car Quest can order filter and O Ring . You may need to use a big pipe wrench to loosen the filter can this time . replace the filter and the square O Ring and reassemble . The can seals on the inside of the can so it does not need to be super tight . People see the leak and tighten the can tighter witch does no good . I guess it makes them feel better .
6brnorma
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Gear.....this is not the M-440
Sorry disregard my post then . Is this a 440B
6brnorma
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I'm assuming so with the Kohler17 engine and a 4 gallon hydraulic fluid capacity.
The nameplate calls it a 440. I believe it was the predecessor to the 440b. I don't see many differences other than the 17hp vs 18 in the b. I'm sure there are other small changes. I think the 440 was made from 1983-1985, and then replaced with the 440B.
So I ran the 440 again yesterday in the snow. (Sure is fun in snow!). I have no issues with the hydrostatic system as it drives and steers really well. This time, I noticed that my hydraulics seemed to perform worse the more I used them. Again in the garage it dumped a bunch more oil. This time I had a better idea of what to look for and it definitely seemed to be coming from the top of the resevoir tank. Oil was filled with air bubbles. I've bought all new Poland a hydro filter to change it out, but I guess it's time to pull the motor and have a better look at the hoses. I can get the motor out without taking all the pumps out since someone modified the torque plate. I'm torn on whether or not to just try and put a new seal kit in the hydraulic pump. I've seen 2-3 other threads on here with issues almost identicle to mine, and it seems that many have rebuilt the pump and the issue was fixed. That doesn't totally make sense to me, as I'm not sure how it would suck air. At this point, the only thing I can tell for sure is that I'm getting tons of air in the system.
I pulled the motor out today. It came out pretty easy. The engine bay really needs a bath. I also drained the hydraulic oil and got a new filter for it. I wanted to check/replace the hose from the oil reservoir and the hydraulic pump. Any other areas to check for an air leak? Once the oil cooler and motor were out, I noticed that one of the steel lines for the lift cylinder was probably forced into place, and the line has a bit of a kink in it. The area seems to be reduced by about 50% or so. Could a restriction like this cause cavitation in the pump? Does anyone have a good place to source parts online? I'm surprised I cant seem to find much.
the kinked line would probably slow down the function of that cylinder somewhat. I would try carefully to remove the kink as best as possible without causing more damage to it. It could be causing some foaming as well, but probably not very much.
SkidRoe
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Hi Arik,
Just curious about the other threads that you read about rebuilding the gear pump. What model machine were they talking about? Are you sure they were talking about the gear pump?
The reason I ask is some other older models (i.e. 743) used a vane pump, which could cause a similar issue as what you are seeing when worn, and rebuilding would definitely help this situation.
I checked the Bobcat parts catalog, and there are no listings for a 440 with a vane pump; they only list gear pumps.
If you do find that it is the pump, I do not believe there are parts available for these older pumps. Loader Part Source sells a new after market replacement pump.
I would look at this after eliminating all of the easy, obvious stuff.
Hope this helps - SR
SkidRoe
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With respect to your damaged lines, I have ordered new ones from Bobcat before, they were no too expensive, about $50 each.
See the link below to identify the ones you need:
http://www.bobcatpartsonline.com/#/...004-Hydraulic System/0001-Hydraulic Circuitry
HTH - SR
Thanks SkidRoe, I will give the dealer a try to see what they would charge. I was also at the hydraulic shop today getting a new inlet hose made up, and asked about the steel one. They seemed to think it might be easier to just make up a new rubber one to replace it. Any issues doing something like that? The guy also seemed to think that my old hose was probably leaking, so I'm hoping that will cure my main problem. This thread sounded somewhat similar to my issues: http://www.skidsteerforum.com/DesktopDefault.aspx?tabid=54&frmView=ShowPost&PostID=4216 I think there was another one from "oldmachinist" that sounded similar too. Was the 453 also a gear pump? I think I even came across 1 or 2 more from 440b's in my endless google searching.
Of course After I got my new hose made up, I was able to try and test my old one. I called on end and put a valve with 80 psi on the other. Sprayed it with some soapy water and it seemed to be holding. Kind of a bummer since I was hoping that would be the source of my air leak. I guess I don't really like/understand why the oil that comes back from the filter, goes directly into a tee fitting and straight back into the hydraulic pump. Seems that it wouldn't give any air bubbles time to work themselves out. I guess I'll try to see if I can pull that tee fitting off the tank without removing it, and double check the o-ring. I'm running out of ideas for how so much air could get into the system.
SkidRoe
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That tee setup for the supply and return is kind of silly. I don't remember my 440B being like that.
Just thinking out loud, could you add another port to the top of the tank, by the breather, as a dedicated return? The fitting that you screw into this new port should have a dip tube brazed into it to get the return in below the oil level, so that the return oil does not free fall into the reservoir, and risk further aeration of the oil.
Then replace the tee with an elbow.
Food for thought - SR
I've been thinking about that as well. That's a good idea to try and mount something at the top of the tank, which would avoid any future leaks. I saw on one of the other threads, someone mounted a valve with some clear tubing coming out of the drain plug on the filter block and routed that back into the tank as a temp setup to see what was going on. I pulled the control valve and filter out of the frame last night, as those were the last parts still inside. Now I can get it outside (when it warms up) and give it a good power wash/degrease. I noticed that when I cracked the hydraulic lines on the lift circuit at the control valve, quite a bit of air and foamy oil came out. There was no pressure at the lift ports. I don't really what know what this means about the valve itself, but I am wondering if its possible that I just had a pocket of air stuck in there that wouldn't come out? Seems unlikely to me. More digging.
Skidsteer1
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Did you get to the bottom of your air leak ? I am going through the same issues with my 440b. I have replaced all the lines going to the pump , and the pintal seals . Still getting air In the tank and lift arms , I really appreciate any help .
