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Discussion Starter #1
I got to blow a little bit of snow recently here in MN. While doing that I was reminded of a question I had last winter that I never got around to asking...

With the tractor running at full throttle and the snowblower on I occasionally hear a curious noise. It sounds sort of like a radiator fan spinning up, staying on for a random amount of time, and then going away. This happens randomly, but fairly frequently. Tractor was nowhere near being hot at the time, though the engine was fully warmed up to operating temp. I didn't think the x7-series tractors have electric fans.

I don't recall this noise in the summer, but the only time I run wide-open in the summer is mowing and I always have hearing protection or noise cancelling headphones on while mowing, so I may just have missed it.

This is 100% NOT the sound of the snowblower auger or impeller. That sound starts when I hit the PTO switch and stays constant. Being that I'm blowing snow at the times this happens I'm not in a position to get off the tractor to look closer or open the hood.

Any thoughts?

Rob
 

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And when the blower is down or up, it seems to change pitch/frequency, I have it too at times. Im guessing its the chain that drives the auger.
:bigbeer:
 

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Not in my case. Doesn't seem affected by blower position or whether I'm actually moving snow. And it isn't a whine like a chain, it is really like a fan spinning up. Like a 'whirrrr'. To me it is identical to what I've heard on electric radiator cooling fans that only come on at high temps (I believe my VTX motorcycle does this in extreme situations).

Rob
 

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Not in my case. Doesn't seem affected by blower position or whether I'm actually moving snow. And it isn't a whine like a chain, it is really like a fan spinning up. Like a 'whirrrr'. To me it is identical to what I've heard on electric radiator cooling fans that only come on at high temps (I believe my VTX motorcycle does this in extreme situations).

Rob

On them 700 series tractors I believe a belt/pulley mounted to the engine drives the fan. Not an electric motor like most of the cars. Most belt/pulley drives use what is called a clutch fan. Meaning that the fan is not mounted solid to the pulley like the good old days. The clutch is a viscous coupling between the fan and pulley. Normally the fan will spin with the pulley but doesn't have any actual drive to it. So the fan essentially free wheels most of the time. When the clutch reaches operating temperature it will lock up putting power to the fan blades. This is when you will notice the noise of it actually moving air. When the temperature drops enough it will go back to free wheeling.

So during cold operation the fan won't take long to cool down the engine enough to turn off. In the summer the fan will have to run for longer periods of time if not constantly to cool things down. This may be why you didn't notice the noise until now.

I believe manufacturers started using clutch fans for noise reduction and fuel savings.

Another thing to note is when first starting a cold engine. The clutch will drag and engage the fan till it warms up.

With the engine off try to spin your fan by hand. If it moves you have a clutch fan. If it is solid you do not.
 

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On them 700 series tractors I believe a belt/pulley mounted to the engine drives the fan. Not an electric motor like most of the cars. Most belt/pulley drives use what is called a clutch fan. Meaning that the fan is not mounted solid to the pulley like the good old days. The clutch is a viscous coupling between the fan and pulley. Normally the fan will spin with the pulley but doesn't have any actual drive to it. So the fan essentially free wheels most of the time. When the clutch reaches operating temperature it will lock up putting power to the fan blades. This is when you will notice the noise of it actually moving air. When the temperature drops enough it will go back to free wheeling.

So during cold operation the fan won't take long to cool down the engine enough to turn off. In the summer the fan will have to run for longer periods of time if not constantly to cool things down. This may be why you didn't notice the noise until now.

I believe manufacturers started using clutch fans for noise reduction and fuel savings.

Another thing to note is when first starting a cold engine. The clutch will drag and engage the fan till it warms up.

With the engine off try to spin your fan by hand. If it moves you have a clutch fan. If it is solid you do not.
I was thinking the same but looking at JD parts on the breakdown it looked like solid mount and nothing in the description.
 

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On them 700 series tractors I believe a belt/pulley mounted to the engine drives the fan. Not an electric motor like most of the cars. Most belt/pulley drives use what is called a clutch fan. Meaning that the fan is not mounted solid to the pulley like the good old days. The clutch is a viscous coupling between the fan and pulley. Normally the fan will spin with the pulley but doesn't have any actual drive to it. So the fan essentially free wheels most of the time. When the clutch reaches operating temperature it will lock up putting power to the fan blades. This is when you will notice the noise of it actually moving air. When the temperature drops enough it will go back to free wheeling.

So during cold operation the fan won't take long to cool down the engine enough to turn off. In the summer the fan will have to run for longer periods of time if not constantly to cool things down. This may be why you didn't notice the noise until now.

I believe manufacturers started using clutch fans for noise reduction and fuel savings.

Another thing to note is when first starting a cold engine. The clutch will drag and engage the fan till it warms up.

With the engine off try to spin your fan by hand. If it moves you have a clutch fan. If it is solid you do not.
Interesting. That may explain it. I'll have to see if I can see the fan while the engine is running and maybe check to see if that's what is making the noise.

Rob
 

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On them 700 series tractors I believe a belt/pulley mounted to the engine drives the fan. Not an electric motor like most of the cars. Most belt/pulley drives use what is called a clutch fan. Meaning that the fan is not mounted solid to the pulley like the good old days. The clutch is a viscous coupling between the fan and pulley. Normally the fan will spin with the pulley but doesn't have any actual drive to it. So the fan essentially free wheels most of the time. When the clutch reaches operating temperature it will lock up putting power to the fan blades. This is when you will notice the noise of it actually moving air. When the temperature drops enough it will go back to free wheeling.
I could be mistaken but I believe the configuration you are describing is used mostly on cars and trucks. The thinking is that as you travel down the road at high speed a belt driven fan can actually inhibit the air flow. So once you reach a certain speed the fan slows or stops and you have straight air blowing through the radiator. When you slow down the fan starts spinning again.

I have never seen this type of clutch fan mounting on a tractor. My 2720 fan for example is mounted tight to the pulley.
 

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I could be mistaken but I believe the configuration you are describing is used mostly on cars and trucks. The thinking is that as you travel down the road at high speed a belt driven fan can actually inhibit the air flow. So once you reach a certain speed the fan slows or stops and you have straight air blowing through the radiator. When you slow down the fan starts spinning again.

I have never seen this type of clutch fan mounting on a tractor. My 2720 fan for example is mounted tight to the pulley.
I was also thinking about air flow while moving. Seeing on the 700's the radiator is behind the engine. So the hot air exits out the front grill. Instead of cold outside air coming in the grill like cars and trucks.
 
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