Air in Cylinder?

KWentling · Jun 30, 2003

I have a BX22 which seems to always get air in the bucket tilt cylinder. Even after fully stroking the cylinder and holding it until the relief valve bypasses to expell the air, after a few cycles it will have air in it again. Its only in the direction of dumping. Once you get it tilted down to a point it will freefall. Makes it a pain when trying to keep the bucket level when cutting. Anyone else have this problem? I have not talked to the dealer yet. Is the cylinder defective? It's been this way since new. Coming up on a year old now with 105 hours on it.

jrlichina · Jun 30, 2003

Do you have the 4-way valve that has the "fast dump" feature? If you push hard to the right when dumping and if it "clicks" over a bit more you have just pushed over into the fast dump mode detent(it has the same feel as the float detent) which has the floppy bucket feel. My guess is that this is what you are experiencing. If that's not it then you have a leaky connection on that end of the cylinder allowing air to enter but then you should also see fluid leaking there too. Answer number one is the most likely reason.

KWentling · Jun 30, 2003

Don't think I have the fast dump feature. It doesn't have the feel like the float does. Manual makes no mention of that feature. Also no leak at the hose fittings. I went over all the fittings to be sure they were tight and not allowing air in. I would think a leak at a seal that would let air in would also let oil out. The only other source of air would be from the hydraulic system itself, I would think. It has Super HDT in it and the oil level is full so I don't know what to think. Thanks for the response.

Mike_Dumond · Jun 30, 2003

Just FYI, you can have an airleak without oil coming out. Might be a seal, fitting or the valve body itself.

Anonymous Poster · Jun 30, 2003

You sure can have an oil leak without having an air leak, it's rare but can happen. Remember the seals were designed to keep fluid in more than air out. I'd extend the cylinder and check the rod to see if you can determine if there's a problem you can see.

marknh000 · Jul 1, 2003

I was having the same experience with my bx22. It turned out to be my "misuse" of the four-way valve. I was pushing the lever right past the normal dump position. The quick-dump position is difficult to feel unlike the float position. I wonder if there is an adjustment that can be made to the valve?

KWentling · Jul 1, 2003

That's must be what I'm doing also. I went back to the manual again and found where it does have this feature. It's in the preoperation section and not in the operating section. So to avoid the air getting into the system, you don't use it? Is there some way to use it that doesn't cause it to suck air? If not, what good is it? I'll try it again this weekend and see if that it what is happening. If so, I'll look into disabling it. Maybe a stop or something could limit the travel of the lever. Thanks for the info guys.

KWentling · Jul 5, 2003

Here's what I did. Went over all the fittings and checked that they were tight. Took the cover off the 4-way valve and checked those connections. Cut a piece of pvc pipe and slipped it over the plunger on the bucket valve so it couldn't get into the fast dump position. Then I cycled the bucket numerous times, holding the lever till the the bypass valve opened. Ever time it would take 3 or 4 seconds to push the air out when in the dumped position. I stopped once in the dumped position to see how much of the stroke had air in it. Almost half the stroke! I could grab the bucket lip and raise it that much. I wonder if the quick couple in that line could be the culprit or if the cyclinder is more likely?
Guess I need to get the dealer involved.

DavidJ · Jul 5, 2003

If you could collapse the cylinder half way by lifting on the lip of the bucket it is a lot more than half full of air. It would need to be about 3/4 full because you're compressing the air as you move the bucket. That seems like a lot of air getting into the cylinder especially since your not seeing a leak.

Just a thought here that I'm sure you've already checked. Are you sure it's air and not something like a valve sticking open allowing the fluid to free flow? I'd agree that it's time to get the dealer involved.

KWentling · Aug 30, 2003

I finally got the BX22 to the dealer this past Monday. I demonstrated the air in the cylinder for the mechanic. Unfortunately it wasn't nearly as bad as what I had been seeing. Called them Friday to see if it was ready. Mechanic says he ran it for quite awhile and could not duplicate the problem. Thinks that I'm not running enough throttle. I suppose that may be a factor, but I don't think air in any hydraulic system could be considered normal, especially in an unloaded condition. I told him I still think there is a problem. He said he would call the Kubota rep. and see what he had to say about it and get back to me. I didn't here back him so I'll have to call on Tuesday and see if they had any ideas. I'm going over to get it this morning so I'll give it a try. If it's still doing it still, I guess I'll have to do the troubleshooting.
Kim