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What Causes a Fan to Rattle ?

Jakus

Jakus

Jakus

Soldato
Joined
31 Jul 2004
Posts
3,730
I have a fan in a special cooler that I can not replace starting to rattle
Anyone out there know what causes the intermittant rattling ?

I have My idea but would like to hear from anyone that's actually found the cause.

The fan has 1 ball and 1 bush bearing

Thanks
 
PC's that are not internally maintained can suffer from premature fan bearing failure especially the cheaper sleeve bearings. You could try to oil very light machine oil, (just a little bit) to help prolong the life but ultimately I think you'll find it's days are numbered.

The other issue I have actually witnessed is caked on crap and dust the unbalances the blades. Make sure they a clean.
 
Thanks for the input Guys,

We can rule out Dirt/balance

If it was the bearing would we not expect it to be noisy all the time ?

I think I know what the problem is but I'm looking for someone to suggest it first

I will say the Fan Runs close to the housing with part of the fan protruding through that housing . Yesterday I tried to shim up the bearing to stop the fan being physically able to rub the housing I also Modified the Housing to make it more Axial to the fan (which it was not and had never been)

I would also expect a running fan to push itself away from that housing when running due to air pressure, even though it's not a true axial type of fan
 
I've heard that loose fan screws can sometimes be the culprit.

One of my P180's case fans (Antec Tri-Cool) started doing this recently after I left it on High for ages (cooling the hdd chamber, ironically I killed the fan while trying to prolongue their lives).
 
Orangey said:
I've heard that loose fan screws can sometimes be the culprit.

One of my P180's case fans (Antec Tri-Cool) started doing this recently after I left it on High for ages (cooling the hdd chamber, ironically I killed the fan while trying to prolongue their lives).
Click to expand...

Nothing loose, and as I say random and intermittant
 
JAKUS said:
Nothing loose, and as I say random and intermittant
Click to expand...

could be that one small area of the bearing is damaged and that it only makes a noise when it makes contact?

you could try lowering the speed/voltage of the fan maybe to see if it makes the noise at low loads and if so what it sounds like........
 
I'm not 100% sure what causes the Rattle on some HIS ICE-Q heatsink fans but I've had a few of their cards and unluckily they all rattled. This was back in 2006 though and we all had radeon X1950Pro cards so I kinda thought the issue would have been solved by now!

A forum poster called Beast stuck a little blob of blue tack on the fans centre/spindle and that removed a fair bit of rattle? I did notice that when I lightly touched the spindle/hub when the card was running the rattle went away so perhaps it is a balance issue with the fan, dunno? :confused:

[edit] found an old pic!

Blu-Tack Mod
x1950histidyra9lt4.jpg
 
Last edited:
Ok, What I think the problem is is the Motor/controller these fans have a small DC brushless motor, basically the fan blades have a "fixed in" permanent magnet and the motors windings are switched by the self contained internal controller..Looks like a 4 phase motor on my Fan and I would guess at certain times and speeds that controller "is not fireing on all cylinders" ..so to speak, So essentially although spinning the fan it is running in "Fits and Starts" and generating the "rattle " from something within it's mechanical assembly which does not enjoy the Rapid Torque reversal's applied to the Fan.

This would indeed give some credit to the Idea of adding some weight to the Fan which would have the effect of dampening some of the unwanted/out of phase inputs the motor is receiving from the faulty controller
 
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