General Strange noise while on the move !!!

[dumbledore]

I was driving along about 40 mph and then some noise from the front of the engine comes.The noise is intermittent, and also intermittent changes pitch. Initially I thought a wheel bearing is gone but the intermittent sound makes me think is not. Then I thought the fan may be kicking in for no reason with this heat and making some bearing noise. Upon stopping and disconnecting the fan, I realised the noise is still there. So my question before I exclude the fan is there a possibility that the fan will rotate by itself when the car is moving at speed (40 mph) driven by the air that passes through the radiator? Is is possible the fan is still at fault. I also let the engine warm up to have a listen to the fan when operated by the car and noise was not to bad, but then when I closed the bonnet a change of pitch similar the one I was hearing in the car occurred.

Can't see what other moving parts in the engine will do this as the pitch does not seem to change with car speed or engine revs.

 

[Brendan W]

Fans can go two tone, high and low pitch, when the bearings are acting up. Yet to hear it from forward motion alone. Try getting a bit of light machine oil on to the fan spindle and see if it goes away - for a while

 

[dumbledore]

Fans can go two tone, high and low pitch, when the bearings are acting up. Yet to hear it from forward motion alone. Try getting a bit of light machine oil on to the fan spindle and see if it goes away - for a while

Cheers, while I was driving it today I just come to the idea to disconnect the fan and then tie up one blade to stop it moving just to confirm the noise is not there on the move. I'll to this next time I drive it for a longer time probably Monday now. If it overheats I just stop remove the tie and reconnect fan.

 

[dumbledore]

Fans can go two tone, high and low pitch, when the bearings are acting up. Yet to hear it from forward motion alone. Try getting a bit of light machine oil on to the fan spindle and see if it goes away - for a while

Looks like the fan is the culprit as I did the trick with the tie to stop the fan blades for rotating during forward motion. I am now suspecting that the new cheep ebay radiator I put recently was not designed properly. I remember when I inspected it that the cooling fins were less dense which will allow more air to pass the radiator which in term will cause the fan to rotate easier. So not happy, but at least the noise is not terminal.