Cat 297c arm drift

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Cat 297c

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My 297c is having a arm and tilt drift problem. I have replaced the relief valves for lift and tilt. I have replaced the 4 check valves in the control valve also replaced the manual lowering valve. I have not repacked the cylinders since it was both lift and tilt I presume it is a valving problem. I have not replaced the main relief valve could it be it? The drift is the same with engine on or off. It does have the bucket leveling system and It has become very notchy when going up. It has started dropping down when you turn the key off.
 

Tazza

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It won't be the relief, that just regulates the pressure that goes to the control block.
It is possible the bucket positioning valve is at fault, it links the lift and tilt cylinders together.
Just how fast do the cylinders move on their own? It's normal for them to move slowly, as in a few inches per hour without a bucket fitted.
 
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Cat 297c

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It won't be the relief, that just regulates the pressure that goes to the control block.
It is possible the bucket positioning valve is at fault, it links the lift and tilt cylinders together.
Just how fast do the cylinders move on their own? It's normal for them to move slowly, as in a few inches per hour without a bucket fitted.
The lift arms will drop 1 inch in 15 minutes whether it's running or not. The bucket cylinder move about the same. It does have the bucket leveling system. So if I capped off the lines to the bucket leveling valve then that should tell if that is good or bad.
 

Tazza

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The lift arms will drop 1 inch in 15 minutes whether it's running or not. The bucket cylinder move about the same. It does have the bucket leveling system. So if I capped off the lines to the bucket leveling valve then that should tell if that is good or bad.
Depending on how the valve is plumbed, yes it would. Not sure you can simply cap off the lines though. They work by diverting a percentage of the oil going to the lift cylinders to the tilt cylinder, so it complicates things.
To fully by-pass it you would need to by-pas it with hoses too.
 
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Cat 297c

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Depending on how the valve is plumbed, yes it would. Not sure you can simply cap off the lines though. They work by diverting a percentage of the oil going to the lift cylinders to the tilt cylinder, so it complicates things.
To fully by-pass it you would need to by-pas it with hoses too.
I have the rebuild kit for the valve I am going to install tomorrow morning.
 
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Cat 297c

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Lets hope that does the job, the only other place is the control block.
I capped off the leveling valve still drifts down 1/4 of a inch per 15 minutes. Could it be the main relief valve the drift is both lift and tilt. Could there be a week spring in the control valve.
 

Tazza

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I capped off the leveling valve still drifts down 1/4 of a inch per 15 minutes. Could it be the main relief valve the drift is both lift and tilt. Could there be a week spring in the control valve.
It can't be the main relief, that comes into effect before that part. Some machines have a relief for the lift circuit, they screw into the control block near the spool for that section. I know Bobcat have these.
 
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Cat 297c

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It can't be the main relief, that comes into effect before that part. Some machines have a relief for the lift circuit, they screw into the control block near the spool for that section. I know Bobcat have these.
I replaced that valve it is a manual lowering valve and I capped it off too no change. The check valves are a little over a year old they do show wear I am going to replace them. Would it be possible for a weak spring on a spool valve.
 
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Cat 297c

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I replaced that valve it is a manual lowering valve and I capped it off too no change. The check valves are a little over a year old they do show wear I am going to replace them. Would it be possible for a weak spring on a spool valve.
I noticed a lot of air coming out of the leveling valve when I took the lines off to cap them. Could it be cavitating from a clogged strainer in the tank.
 

Tazza

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I noticed a lot of air coming out of the leveling valve when I took the lines off to cap them. Could it be cavitating from a clogged strainer in the tank.
I guess it is possible that the air is the issue. If you are getting air in the hydraulic system, you do need to work out why, a blocked filter could indeed be the cause.
 
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Cat 297c

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I guess it is possible that the air is the issue. If you are getting air in the hydraulic system, you do need to work out why, a blocked filter could indeed be the cause.
Well after changing the bucket leveling diverted valve and totally cleaning out system. The bucket and arms still drift. They drift both directions that means if I use bucket to push machine up it drifts up until machine is back on ground. I have not replaced the main relief valve. I have not checked each spool in the control valve, not sure what to Check next.
 

Tazza

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Well after changing the bucket leveling diverted valve and totally cleaning out system. The bucket and arms still drift. They drift both directions that means if I use bucket to push machine up it drifts up until machine is back on ground. I have not replaced the main relief valve. I have not checked each spool in the control valve, not sure what to Check next.
Did you repack the cylinders?
From what i read, i could see you have done just about everything else
 
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Cat 297c

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Did you repack the cylinders?
From what i read, i could see you have done just about everything else
Repack all cylinders. They did not show any wear but repacked. Today I changed springs on the spool valves and adjusted the tilt and lift relief valves. I just got it back together I marked cylinders and left them up to see how much drift. The first hour only move about 3/16 of a inch down on the lift. All the spools looked good no wear no scratches.
 

Tazza

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Repack all cylinders. They did not show any wear but repacked. Today I changed springs on the spool valves and adjusted the tilt and lift relief valves. I just got it back together I marked cylinders and left them up to see how much drift. The first hour only move about 3/16 of a inch down on the lift. All the spools looked good no wear no scratches.
That sounds pretty good to me. Hopefully you got it fixed.
I was once told that there was an acceptable amount of drift per hour, i believe that is less than what was specified.
Not sure why they leak down, it could be the nature of the seals that the piston never fully seals like a lip seal would do.
 
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