Hi, new to the forum, looks like a valuable resource. I have an 825 skid steer which I was using to move snow. With the loader all the way up to dump, there was some growling in the hydraulic system, sounded like cavitation. Went to turn around and the right side would not go forward, only backward loudly. The left side drives fine. I noticed that one of the hydraulic spools sprung a leak, and the oil level was below add, but not excessively when I checked it right after this issue happened. Both drive pumps are rebuilt with very few hours. Could the right side motor be shot, can this happen so quickly and still drive backwards? Or is it possible that the low oil level caused air to enter the system and this is the result? Any ideas? Thanks.
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sterlclan
Well-known member
- Joined
- May 1, 2004
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- 528
sounds like a broken part.....chain? check the drive motor mounting bolts and the sprockets in the chain case low oil"could"be some issue not sure if it would stop the drive though.....good luck..Jeff
Even with low hours on the pumps its still possible a part has broken. If its only one direction it could be a relief on the drive system but you did say there is a lot of noise. It could be the motor too, if you can swap motors from side to side and see of the problem goes to the other side you know what is causing the problem.
With the extra noise, was there more resistance on the steering stick? vibrations?
MMLee
Member
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- Dec 22, 2008
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- 6
The first thing to look at is the chain and sprocket to make sure they are in tact. If they are then the next thing I would do is to flip the relief valves in the drive pump. It could be that debris has gotten into them from the recent rebuild. low oil wouldn't cause this otherwise it would happen on both sides and in both directions. These are fairly simple checks to do before condemning the drive motor. Best of luck!
I am helping a friend fix a Bobcat 720 that he got for 500.00. It has the same problem and we disassembled it yesterday. The drive motor was in good shape and I connected it to my bobcat for testing, motor works fine. The Vickers hydraulic motors are all steel inside and cannot "just go" unless the shaft broke in which case there would be no drive. As mentioned above try removing and exchanging your replenishing valves, and inspect for dirt causing them to stick. Also hook up an oil pressure gauge on your hydraulic filter and measure charge pressure. My shortcut for testing motors is simple if you have extra hydraulic hoses- remove the lines going to both hydraulic motors and put hoses to the "bad" motor to the "good" side and loop the "bad" side fittings. If the "bad" motor works by operating the "good" side you need to pull the pump and inspect it. The 700-800 series machines of the 1970's have some really strong hydrostatic systems and are generally easy to diagnose.
This happened to my 825 last summer. After tilting up the cab, I removed the fiberglass cover over the pumps and motors, and found the ball end on the control rod had fallen out. It looks like a little tie rod end, and there is a steel ball held in place with some plastic? material. Anyway, the material was gone, melted, dissolved, I don't know, but the Bobcat dealer ordered up a new one, and it turned out to be a cheap fix, for a change, (not counting my time!) Mine wouldn't go forward, and after a time or two it wouldn't go in reverse either, but luckily it wasn't serious. I hope your fix is easy as well. Jerry
I also have an 825 that is doing the same thing except on the left hand side. reverse works fine, forward does nothing. hydrostats have supposedly been rebuilt by previous owner. left side works fine. What ended up being the solution to your problem cyuskiw? my drive chains are good, linkage is in tact and moving as it should, all 3 filters have been changed. Any other 825 owners/mechanics know of anything these machines are bad about that might cause this problem? where are the relief valves located on the hydrostats so I can check/clean and polish them if they are a possibility.
The relief valves are screwed into the drive pump.
It could also be a shuttle or seal in the drive motor, can you swap them from side to side? see if the problem moves. If it does, its the motor, if not pump/relief.
You can swap the relief valves. The front section drives the right side, rear the left. The relief valves are on the square part of the pumps, at the top. Swap'em. If it changes,THERE'S YOUR PROBLEM. Hope this helps. PS. The motors are hydrostatic/piston motors. If you had a problem with them. It would be in both directions, plus alot of case drain flow.
i also have an 825 and this happened twice,once on the left and once on the right.both times it was just a hydraulic hose going to one of the drives.you have put the machine on blocks and lift the fiberglass cover and move the levers while its running.if the leak is submerged in fluid it might be hard to see.any hoses in there are a bear to change
Bobcat blood
New member
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- Oct 15, 2022
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Hello, i am also with a 825 clark issues.
What would be alot of case flow ? Applying the left Forward nothing unless full throttle it will jerk.
And alot of case flow when applied.....
Any chance relief valve could cause the Jerks and noise? Half throttle no left joy control forward .but reverse will work occasionally.
What would be alot of case flow ? Applying the left Forward nothing unless full throttle it will jerk.
And alot of case flow when applied.....
Any chance relief valve could cause the Jerks and noise? Half throttle no left joy control forward .but reverse will work occasionally.
