Tractor Transmission noise

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Banjo

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I have a Agco Allis 6690 that makes some gear noise when its in gear....but it is inconsistent, sometimes it only does it in the forward gears and then sometimes only in reverse. When it is in neutral and running there is no noise. Oil levels are good...but the noise sounds like you hear the gears in the trans turning. Otherwise it shifts and runs just fine, Anybody have an idea of what may be causing it? Its only noticeable inside the cab and mostly in the higher gears.
Maybe worn bushings or spacers in the transmission?
 
Any hydrostat functions? Pump whine could be your culprit. Whine as I know it is usually bubbles in the system caused by cavitation due to an irregular obstruction in the system, like a flow limiting orfice that causes laminar flow to revert to turbulent, or a pump compressing fluid....aka hydrostat.

I have a small manual tractor other than hydro steering, and I hear it at certain steering positions. Have another larger with hydro steering and shuttle shift, manual otherwise, and it usually (comes and goes) is quiet till I get up to within 200 rpm of rated (2600) and then quiets somewhat above that....gov. lets it get on up to kissing 3000 (factory setting) where it's nice.

I hear some folks with full hydrostat complain about it. Can't comment on that.
 
The steering, hydraulics, and transmission all pull from the same reservoir, but the the transmission is all manual shift. It doesn't make a whining sound too much, its just like you can hear the gears tumbling.

I have a jeep that does almost the same thing when I put it in 4 wheel drive.....a loud rumbling sound. But it works fine.
 
Could be bearings ,won't notice as much under a load,,, my old international did it,,, though ain't telling you,,, you should do it..but I put a bottle of Lucas in mine,, quite it down a lot
 
Maybe start by cutting open the hydraulic filters and looking for metal debris.

If none is there, nature of the beast. If there is some, you have a problem somewhere.
 
How many hours is on the tractor. Also if it has wet brakes, I am sure it does it takes special hydraulic oil for those. It may have the wrong oil and the brakes coming apart and causing problems, stopping up filters, oil lines, etc. as it does make a mess and is not that uncommon. If you bought the tractor new you know the history and that will eliminate some things. I would change the hydraulic oil with what is required, filter ASAP and see if that helped.
 
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jltrent":13uj7z47 said:
How many hours is on the tractor. Also if it has wet brakes, I am sure it does it takes special hydraulic oil for those. It may have the wrong oil and the brakes coming apart and causing problems, stopping up filters, oil lines, etc. as it does make a mess and is not that uncommon. If you bought the tractor new you know the history and that will eliminate some things. I would change the hydraulic oil with what is required, filter ASAP and see if that helped.
Click to expand...

7000 hrs. I changed the hyd filters a while back, but not the oil. the oil level was low then so I added more to it to bring up to level. I also put lucas oil in it...as someone mentioned thinking it just wasn;t getting enough oil on the gears causing them to be noisy....but it hasn't helped.
It could be in the brakes maybe. I'm gonna have a local mechanic look at it next week. I've owned it about 2 years.
 
Banjo":3hna0kn7 said:
The steering, hydraulics, and transmission all pull from the same reservoir, but the the transmission is all manual shift. It doesn't make a whining sound too much, its just like you can hear the gears tumbling.

I have a jeep that does almost the same thing when I put it in 4 wheel drive.....a loud rumbling sound. But it works fine.
Click to expand...

Let's flip it over. I have a couple of 1960's Fords, 2000 and 3000. Not too long ago I changed tranny fluid and went from gear oil to 134A (JD 303 for a popular reference). Since gear oil is 90 and this oil is in the 10-30w category, it's much lighter and as such doesn't coat the gears as heavily as regular gear oil. Hence much noisier shifting and running, especially considering the age of the OEM bearings involved. Bright side is that in the winter it shifts easier but that wasn't the reason for the change.
 
A friend of mine who does some tractor repair told me to drive it and apply the brakes or each brake one at a time and see if the noise stops. I did that and it doesn't stop.
I cut one of the hydraulic filters open ....with a chop saw.... I did see metal shavings but I think it was mostly from the chop saw...Hmm. I probably need to use a can opener.
I'm starting to think it may a bushing or bushings in the transmission. All last week it only made the noise in the forward gears and not reverse. Today, its quite as a mouse(normal) in the forward gears and noisy in reverse.

Its as if something is changing positions every so often....
 
Sometimes you can speculate what it may be... I've been around tractor ""brand" mechanics that can diagnose one,upon hearing it... But sometimes it takes exploratory surgery.....
 
Banjo":12wpnw1u said:
A friend of mine who does some tractor repair told me to drive it and apply the brakes or each brake one at a time and see if the noise stops. I did that and it doesn't stop.
I cut one of the hydraulic filters open ....with a chop saw.... I did see metal shavings but I think it was mostly from the chop saw...Hmm. I probably need to use a can opener.
I'm starting to think it may a bushing or bushings in the transmission. All last week it only made the noise in the forward gears and not reverse. Today, its quite as a mouse(normal) in the forward gears and noisy in reverse.

Its as if something is changing positions every so often....
Click to expand...

Best to use a cutter that's made for it.

Anyone who races or builds engines will have one handy.
 
Might be worth the expense of having a one-time trans/hyd oil analysis done before you spend big bucks going in to the innards of the thing. It will at least let you know how much metal or fiber particles may be in the lubricant.
 
greybeard":1iqecdpi said:
Might be worth the expense of having a one-time trans/hyd oil analysis done before you spend big bucks going in to the innards of the thing. It will at least let you know how much metal or fiber particles may be in the lubricant.
Click to expand...

Where would you have something like that done?
 

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