LS180 Right Servo Sticks on in Forward

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sfosmith

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Joined
Jan 18, 2011
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I have a LS180 year 2000. This winter the right side drive wheels stick on especially after a little push. The right wheels will turn even at low RPM. I have to shut off the motor to stop the hydraulic drive. I believe it is the control mechanism in the right side servo. Is there an easy solution to getting this to work right or is it a motor pull? This year machine called for using motor oil instead of hydraulic fluid in the system. This is central California and not below freezing but wondering if the thick cold oil is a problem. I've never had a problem in the last 9 years. Low time machine. Looking at the parts schematic for the right side servo is complicated and hard to understand the forward, reverse and neutral control mechanism, which I suspect is the cause of the sticking.
 
It could be a couple different things causing your problems. First I would look at the motor mount under the seat, it is between your servo pumps, make sure that isn't blown out or the rubber is broken loose from the metal plate that bolts in place. That will need to be replaced first to get your steering where it should be. Next question is does your steering handle move freely with the machine running or does it feel jammed up? I have seen snap rings in the servo assembly break and jam the servo in the forward or reverse position and the control handle won't move. If the control handle is free to operate normally It sounds like your cam bushings inside the pump are wore out. They have a thin layer on them that will tear up over time and cause the swash plate inside the pump to stick in the direction you are trying to go, it will also make it difficult to neutralize the pump to make the machine sit still. It sounds like you will have to pull the pump out of the machine and pop it apart to find out what is wrong. Only a couple hour job to drain the oil, pull the pump and have it apart on a work bench.
 
It could be a couple different things causing your problems. First I would look at the motor mount under the seat, it is between your servo pumps, make sure that isn't blown out or the rubber is broken loose from the metal plate that bolts in place. That will need to be replaced first to get your steering where it should be. Next question is does your steering handle move freely with the machine running or does it feel jammed up? I have seen snap rings in the servo assembly break and jam the servo in the forward or reverse position and the control handle won't move. If the control handle is free to operate normally It sounds like your cam bushings inside the pump are wore out. They have a thin layer on them that will tear up over time and cause the swash plate inside the pump to stick in the direction you are trying to go, it will also make it difficult to neutralize the pump to make the machine sit still. It sounds like you will have to pull the pump out of the machine and pop it apart to find out what is wrong. Only a couple hour job to drain the oil, pull the pump and have it apart on a work bench.
Thanks for the reply, Aaron. Everything checks out ok on the outside so it is an internal problem. Now I'm looking for a repair manual on the servo pump after I get it out. Either that or a hydraulic motor shop. I'm not impressed with my local New Holland dealer's service facility. I don't understand the design of cam bushings and swash plates, so will have to dive in if repair shops to expensive.
 
Thanks for the reply, Aaron. Everything checks out ok on the outside so it is an internal problem. Now I'm looking for a repair manual on the servo pump after I get it out. Either that or a hydraulic motor shop. I'm not impressed with my local New Holland dealer's service facility. I don't understand the design of cam bushings and swash plates, so will have to dive in if repair shops to expensive.
A repair shop shouldn't be very expensive, they shouldn't have much more than an hour into it, and once they find what it needs the NH dealer should have the parts in stock. The most expensive parts will be the labor to remove the pump from the machine, and then the parts internally in the pump. Since you will have it out I would replace the pump seal, the o-ring where it mounts to the bell-housing, and the o-rings on the external fittings if they haven't been done recently. There is also an o-ring and a gasket that seals mating surfaces in the pumps that they may want to replace, and most likely the cam bushing is your problem. I have seen the internal servo arms bend also, but usually there is a larger problem that causes that.
 
A repair shop shouldn't be very expensive, they shouldn't have much more than an hour into it, and once they find what it needs the NH dealer should have the parts in stock. The most expensive parts will be the labor to remove the pump from the machine, and then the parts internally in the pump. Since you will have it out I would replace the pump seal, the o-ring where it mounts to the bell-housing, and the o-rings on the external fittings if they haven't been done recently. There is also an o-ring and a gasket that seals mating surfaces in the pumps that they may want to replace, and most likely the cam bushing is your problem. I have seen the internal servo arms bend also, but usually there is a larger problem that causes that.
In the past Ive had trouble with one side drives faster than the other. Or when in neutral it would creap a little. I do have to say that i have never fixed it myself but usually take it in for maintenance they would correct it. Had always been told its just a minor adjustment in the linkages. And i can tell by what it cost it was just labor and not much of it. I wouldn't be to quick to start the tear down so fast. Some one in here can explain the process way better than i understand it.
 
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