Question about radiator fans

[Lord Derosso]

I havent had the Vulcan long and its the first bike I have owned with a large radiator with a fan behind it. On a hot day and riding in town traffic I have noticed that the fan will come on periodically, which is cool because a 750 I had years ago with a radiator used to overheat if stuck in heavy traffic and I even had to stop on the Auckland motorway once and leave it for a while to cool down in peak early morning mid week travel - I hadnt planned the return trip from Whangarei to Wellington to take in the sheer amount of traffic mid week!.

It was cool yesterday and my flatmate and I decided to go fishing as I have the week off and after a blast through town, we got home and the radiator fan wasn't running as I parked the bike. It seems to start if we get stuck at the lights but I am not 100% its the fan as the bike isnt exactly quiet. However on a hot day I have stopped the bike and the fan can run for several minutes after I have turned the engine off and it sounds like a turbo whine. The manual does warn owners NOT to put fingers near the fan as it can go on at any time, even after the bike is turned off.

My question especially to other Vulcan owners is how often does/did your fans go on and stay on while the bike cooles down, and should they make any noise? Ta.

[JimO]

the fan on my raptor comes on at 105dg and goes of after a minute or so , it only comes on when in slow traffic and last weekend on the toy run and it makes a fan type noise

[Conquiztador]

The water in to the radiator will be coming in from the top and go back in to the motor from the bottom. While the motor runs the water is happily pumped around. But when motor stops so does the pump.

So... as the sensor for the water temperature is at the bottom of the radiator where the water goes back in to the motor and the water comes in at the top from the cylinders and is at it's hottest it can take a while for the water in the radiator to cool down enough for the sensor to turn off the fan when the motor is not running.

By making sure you have that green/yellow coolant in the water and there is the right mix of it, you will keep the "water" at approx 10 degrees cooler.

but that is what the fan is there to do: to help cooling the water. Re the noise: Normally takin off the radiator is a simple task. (Two hoses and a bolt or two, and the sensor wires) and you will get to the fan to have a good look/test of it.

Oh, and by shorting out the sensor you will get the fan to run if you want to listen to it while bike parked.

Good Luck!

[Lord Derosso]

Is it a good idea to use something like WD40 or CRC and give the fan a quick spray when cold? I am not keen to use sprays around some parts of the bike, especially after an experience with a horn on another bike which ceased to work after an anti rust attempt with CRC. Had to open it up and clean off the spray. It has only really been of real concern once after a very hot day riding around town for an hour and it kept running for about three minutes and was quite loud like a buzzing or hissing fan sound but as you say, its on for a reason. The first time I heard it I thought the radiator had lost its tap as in a car when it overheats, but of course there was no leakage, just the noise. I think it must be set to run at different speeds depending on the load or temperature and on that particularly hot day and in slow traffic conditions, the engine must have got a lot hotter than normal. Though if the pump stops with the bike, why would the fan come on if the sensor is located at the coolest part of the radiator unless the water is still circulating down through the radiator therefore the hotter water quickly settles down to the sensor and sets off the fan, which is why the manual warns you not to go near the fan even if the key is turned off. The bike was recently serviced and runs well, just the fan is annoying me because its a new feature for me. Thanks.

[Conquiztador]

Though if the pump stops with the bike, why would the fan come on if the sensor is located at the coolest part of the radiator unless the water is still circulating down through the radiator therefore the hotter water quickly settles down to the sensor and sets off the fan, which is why the manual warns you not to go near the fan even if the key is turned off. The bike was recently serviced and runs well, just the fan is annoying me because its a new feature for me. Thanks.

This is how my logic tells me:

When motor running and pump is working the cool water that the fan cools down is then passed down and pass the sensor therefore turning the fan off.

When you stop the motor and the water is hot enough to start the fan, the water does not circulate, and so the hot water that sits where the sensor is will be hotter then the water that is where the fan blows air. After a while the cool water will slowly cool down the hot water over where the sensor is, but as there is no water circulation, it can take a little longer then when water pump is working.

Yes, you can spray CRC on the fan. But I be very surprised if it will do anything at all to fix it. Try to turn the fan by hand and check if it turns freely and if there is a noise like the blades are catching something? You might just have some rubbish in there.

Good Luck.

[slimjim]

remember too its external...unlike a car the fan's or fan is covered by bonnet,guards,grill, so noise is trapped more so by bodywork....on your bike it sits openly behind rad, and are loud via blades and air draw...if it doesn't kick in...then thats when you should be worried...otherwise its a normal sound,

[Rudra]

If it's the Clymer manuel you have, check page 278.

[Lord Derosso]

If it's the Clymer manuel you have, check page 278.

All I have is the owners manual and thats piss poor on the radiator.

Can you copy and paste a reply with the page please, or PM me?.


Cheers ROss

[AlBundy]

I'm a radiator fan too.

Without radiators, we'd be a lot worse off as far as performance and reliability...

Either that, or we'd have figured out a totally different way of cooling things...