Hello everyone, I am new to the forum and bobcat ownship. I am very glad to find this wonderful site. I just bought a 89 853 loader. It has problem with the tilt control. The engine runs fine and the loader drives well. The lift controls are a little touchy/jerky but they work. However, the tilt cylinder only goes one way: down/forward. When I press the heel down, I can hear some hydraulic noise from below the seat, but the bucket does not move at all. I did some trouble shooting by disconnecting the hydraulic lines at each end of the tilt cylinder. The bucket moves back up if i disconnect the hydraulic line at the base of the tilt cyclinder. This suggests that there is some kind of blockage that prevent the hydraulic fluid from returning. I am not familiar with Bobcat hydraulics at all. I am curious if there are some kind of check valve(s) that may be stuck shut some where? thanks in advance for any help. toolnut
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I assume the noise you hear is a whistle, this is oil going over the relief valve. I can't think of what would be holding pressure in that hydraulic line..... Hopefully someone else will know what the cause would be.
There are load checks in the control block, but i wouldn't expect them to cause these problems.
There are load checks in the control block, but i wouldn't expect them to cause these problems.
The bucket on my 853 had no down pressure, like it was in float position. I could tilt it back, it had full power on the tilt back. I found a peice of metal had my releif valve stuck open, very small peice at that. Just lucky and found it the first try. I had replaced my hyd pump prior to the problem, that's where the metal came frm. dennis
PS I didn't notice no sounds
Sounds like that I should start tearing into the hydraulic lines to find out where the blockage is. Any suggestions before I dig into that? toolnut
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I'd start by unhooking that cylinder and and removing it. A bypassing piston seal in the cylinder can cause that sort of behavior.
After its off run the ram in and out by hand to remove the oil. pull the ram out by hand.
Plug the port that extends it the ram. Now hook your air compressor to the other cylinder port and put the pressure to it. It will retract the ram, and if the piston seal is good it will stay retracted. And if the piston seal is bad it will retract first and then extend.
I'd start there
Regards
Ken
As ken said, start there.
I wouldn't start checking hydraulic lines for blockages, with 2,500 odd PSI behind anything that may be in a line it would simply be pushed out, there would be a LOT of force behind anything in a line. I would seriously doubt anything could fall off and plug a line. If anything, it could be a stuck poppet in the control block, but they usually leak not stick closed. Start with the simple stuff, the ram. I'd un-hook the line that you removed to retract the ram and see if you can get oil to come out, if not the problem is in the control block. If you get a good amount of oil from both lines the problem is inside the ram.
I do get decent amount of oil out of both lines. I will check the Ram first, as suggested above. Thanks for all the input. I will let everyone know what I find. thanks
just a thought ---Not all machine have it as it is an add on , there is a orifice valve that screws in between the end of the hose and the rod end of the tilt cylinder , looks like a fitting with a steel peg thru it , they put them in there to slow the down stroke of the cylinder so if you have a heavy hammer of grapple full of weight and go down fast it doesn't bend the chrome rod , if you have this valve on your machine remove it if hose is long enough if not you can gut it by driving out the peg , removing the orifice and putting the plug back -----
Ok, not good here is what happened yesterday. We removed the tilt ram and took it to a Friend's bobcat 753 and hook it up to its tilt hydraulic lines. It worked great. Moved in and out smoothly, no problem. So the ram is good. Went back to my 853. Put everything back together. The very first try to get the cylinder to retract, it worked. After extending the cylinder out, then it was back to the same old self--the bucket does not want to tilt back any more. There is something else interesting about the hydraulics that I did not mention before. The control for the lift cylinders is a little touchy. When I push the toe down a little bit, the bucket actually moves UP, slowly. I have to really push it down with my toe to get it to go down. I did not mention this before because I figure it may just need a little bit of mechanical adjustment. However, I beginning to think that these symptoms may be related. Any followup ideas? thanks, toolnut
It could be an adjustment, but i'm not too sure how the linkage is setup on yours. Mine is a fixed length piece of steel bar with holes drilled at either end. If it is simply adjustment, you can loosen the bolts holding the pedal to the chassis and move it that way to get it at the same angle as the other side. If you are referring to the fact that you need to push the pedal a fair way down before it does anything, it does point to a possible control block problem, i just don't know what...
Are the bolts on the cap end of the controll valve spool tight and in place , is the cap which houses the spool spring cracked , early cap were thin edged and replaced with a thicker edge and longer bolts , I have seen quite a few break years back , also you could have bent the spool , does your machine have the white plastic pieces that contact the seat bar when down which unlocks the foot pedals , are they fully releasing the linkage , did you check to see if you had the orifice valve on the end of the hose going to the cylinder
