Chain sound?

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ThomasM

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Hi, I have a 743B with 3700 hrs, everything works great, but when I run the machine at 3/4 to full throtttle and drive it around I hear a metalic grinding noise comming from the left side, maybe both sometimes. Less than 3/4 it does not seem to be noticable. Sounds like a chain grind when turning or full speed ahead, also when going down hill or if you hit a bump, its like the chain "catches up" and makes this sound. I thought that this thing had auto adjusting chain? or is it just plain stretched out?? And how do you adjust it or fix this? Thanks!
 

Tazza

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The chains are not self adjusting.
It is normal to hear a bit of a chatter of the chains when going down a hill at speed, you will hear the chain slapping against the plastic guides. It shouldn't be so stretched that it will touch the base of the chain case.
The noise you hear may not be the chains.... Could it be the park brake not dis-engaging fully? this could make a metal scraping sound as the brake disc rotates past the brake assembly.
 
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ThomasM

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The chains are not self adjusting.
It is normal to hear a bit of a chatter of the chains when going down a hill at speed, you will hear the chain slapping against the plastic guides. It shouldn't be so stretched that it will touch the base of the chain case.
The noise you hear may not be the chains.... Could it be the park brake not dis-engaging fully? this could make a metal scraping sound as the brake disc rotates past the brake assembly.
I will have to look at the p brake. I also hear it when putting the left side under load (turning on pavement with that side)....At full throttle this sound is loud. like stop and see whats going on. Maybe like you say it is just hitting on the guides. Could it by a hydraulic motor issue?? Thanks!!
 

OldMachinist

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I will have to look at the p brake. I also hear it when putting the left side under load (turning on pavement with that side)....At full throttle this sound is loud. like stop and see whats going on. Maybe like you say it is just hitting on the guides. Could it by a hydraulic motor issue?? Thanks!!
Block the machine up in the air and have someone sit in it and operate the steering. See if you can hear the noise and from where. Also make sure that tires on same side turn the same to make sure a chain hasn't jumped off. If that all looks good, turn machine off and have the other person hold one tire and you rotate the other tire back and forth on the same side to check how much slop the chain has. Do this on both sides to see how much difference there is. Also check each tire for end play and up and down play. Let us know what you find
 
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ThomasM

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Block the machine up in the air and have someone sit in it and operate the steering. See if you can hear the noise and from where. Also make sure that tires on same side turn the same to make sure a chain hasn't jumped off. If that all looks good, turn machine off and have the other person hold one tire and you rotate the other tire back and forth on the same side to check how much slop the chain has. Do this on both sides to see how much difference there is. Also check each tire for end play and up and down play. Let us know what you find
Hi, I did what you suggested above. No end play, No up and down play. All the chains are connected. With the whole machine jacked up, the wheels have about 1"-1.5" of play at the top of the tire when you try rotate it. It makes NO noises when running the motors with the machine jacked up. Does not seem like much slop in the chains to me with only 1" of play. The tires are badly worn. Hope it is not a motor issue. Thanks!
 

OldMachinist

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Hi, I did what you suggested above. No end play, No up and down play. All the chains are connected. With the whole machine jacked up, the wheels have about 1"-1.5" of play at the top of the tire when you try rotate it. It makes NO noises when running the motors with the machine jacked up. Does not seem like much slop in the chains to me with only 1" of play. The tires are badly worn. Hope it is not a motor issue. Thanks!
I think you pretty much eliminated the chain and bearings and will have to look at the motor. You can try swapping the motors from one side to the other to see if the noise follows the motor. Tazza can tell you how much of a job that would on your machine.
 

Tazza

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I think you pretty much eliminated the chain and bearings and will have to look at the motor. You can try swapping the motors from one side to the other to see if the noise follows the motor. Tazza can tell you how much of a job that would on your machine.
Swapping motors is fairly easy, still not really pleasurable! Just remember to remove the tyres first, it makes it a lot easier!
Its really hard to say, you could have a problem with a sprocket in the chain case, bad chain or a motor issue. The only thing you can really check is that BOTH the rear and front wheels on each side move forward and backwards the same amount, this will indicate if the front or rear chains have stretched. You don't want more play in the front than the rear. Remember one side at a time, checking fronts or rear together will proove nothing.
Nothing else springs to mind that could be a problem.....
 
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ThomasM

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Swapping motors is fairly easy, still not really pleasurable! Just remember to remove the tyres first, it makes it a lot easier!
Its really hard to say, you could have a problem with a sprocket in the chain case, bad chain or a motor issue. The only thing you can really check is that BOTH the rear and front wheels on each side move forward and backwards the same amount, this will indicate if the front or rear chains have stretched. You don't want more play in the front than the rear. Remember one side at a time, checking fronts or rear together will proove nothing.
Nothing else springs to mind that could be a problem.....
Hi, Ran it again tonight to check it out closer: here is when this chain grinding sound happens: 1. 3/4 + throttle 2. Both sticks full forward and then slightly pull back on just one stick (left or right stick) the left stick seems to make more noise. 3. It does not make the sharp metallic noise if you have both sticks 7/8 of the way to full and then pull back on one or the other. You can do circles all day on the pavement and it will not do it. Only does it as described above. Weird. \ Any more ideas, thanks for the ones so far.
 

Tazza

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Hi, Ran it again tonight to check it out closer: here is when this chain grinding sound happens: 1. 3/4 + throttle 2. Both sticks full forward and then slightly pull back on just one stick (left or right stick) the left stick seems to make more noise. 3. It does not make the sharp metallic noise if you have both sticks 7/8 of the way to full and then pull back on one or the other. You can do circles all day on the pavement and it will not do it. Only does it as described above. Weird. \ Any more ideas, thanks for the ones so far.
Is it a grind or more of a squeel? The hydrostats do make noise when they are running, i'm thinking it could simply be pump noises.... With the way you have described it, this only happens at high throttle which is exactly the opposite to what normally happens. At low RPM the pumps growl and high they seem to be quiet and happy.
How do the sticks feel? do they shake when you hear this sound?
Another thing could be bad oil, what colour is it? is it foamy at all?
 
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ThomasM

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Is it a grind or more of a squeel? The hydrostats do make noise when they are running, i'm thinking it could simply be pump noises.... With the way you have described it, this only happens at high throttle which is exactly the opposite to what normally happens. At low RPM the pumps growl and high they seem to be quiet and happy.
How do the sticks feel? do they shake when you hear this sound?
Another thing could be bad oil, what colour is it? is it foamy at all?
It is more of a metal grind, yes there is kind of a feel in the sticks: As you pull slightly back on one stick while the other is full forward it kind of feels like it does not want to be pulled back and then it makes this noise but once you pull it back enough so you have more of a differential travel speed between the two sides then it quits making the noise like it breaks free from the other side even know they are independent. I did adjust the linkage so the neutral is correct. I also noticed that the linkage between the two sticks are semi-independent of each other as they travel together if you move only one stick forward. Is this correct? This is hard to explain! I have changed part of the oil out. 10w-30 now. I do not notice the oil being foamed at all. Thanks.
 

Tazza

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It is more of a metal grind, yes there is kind of a feel in the sticks: As you pull slightly back on one stick while the other is full forward it kind of feels like it does not want to be pulled back and then it makes this noise but once you pull it back enough so you have more of a differential travel speed between the two sides then it quits making the noise like it breaks free from the other side even know they are independent. I did adjust the linkage so the neutral is correct. I also noticed that the linkage between the two sticks are semi-independent of each other as they travel together if you move only one stick forward. Is this correct? This is hard to explain! I have changed part of the oil out. 10w-30 now. I do not notice the oil being foamed at all. Thanks.
Its normal for the sticks to move a little together, don't worry about that.
The noise i believe is just pump sounds, they do make grinding and squeeling sounds. Has it gotten better with the fresh oil?
 
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ThomasM

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Its normal for the sticks to move a little together, don't worry about that.
The noise i believe is just pump sounds, they do make grinding and squeeling sounds. Has it gotten better with the fresh oil?
No difference with new oil, I was thinking though, maybe if the linkage could be adjusted so the sticks can only go 7/8 of the way, then the noise would be gone. maybe they are overtraveling if that is possible?? Is there an adjsuter to adjust the max forward travel? Thanks!
 

Tazza

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No difference with new oil, I was thinking though, maybe if the linkage could be adjusted so the sticks can only go 7/8 of the way, then the noise would be gone. maybe they are overtraveling if that is possible?? Is there an adjsuter to adjust the max forward travel? Thanks!
There is no adjustment for that. And no, there is no such thing as over travel with this pump setup. All it has is a maximum angle it can rotate to give a maximum flow of oil.
The last thing you can try is swapping motors over. If the noise changes sides its a motor if not it sounds like the pump may want some work doing to it...
 
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ThomasM

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There is no adjustment for that. And no, there is no such thing as over travel with this pump setup. All it has is a maximum angle it can rotate to give a maximum flow of oil.
The last thing you can try is swapping motors over. If the noise changes sides its a motor if not it sounds like the pump may want some work doing to it...
Ok, thanks guys for the good information. I will have to look into it more.
 

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