low noise

Hi all i have a 2001 2.5 which has done 150k Ive noticed recently a low hum that starts at about 1000rpm and follows through you can't hear it when driving but if you take your foot of the accelerator you can hear it drop with the tacho.
It happens in park and neutral as well.
The car drives fine no other obvious noises , it has got the ace system but i couldn't tell you if that still works.

viscous fan stuck so it's running full bore without any slippage??

thanks I've checked that , i think your half right as its constantly running , but i took the belt of and it went away so i think its a stretched belt.

To be fair, the viscous fan "runs" all the time, it'll just slip more or less depending upon the temperature etc.

ok with the belt and the fan off theres no noise , but with the new belt back on the noise is back, does that mean a bearing on one of the pulleys has gone? i couldn't feel anything on them. it can't be the crank as that would have been moving with the belt off anyway.

Best way to check if the viscous coupling is working is to try and stop the fan with a rolled-up newspaper. When the engine is cold, you should be able to do so - and naturally when it is hot, you shouldn't

jimdonut said:

ok with the belt and the fan off theres no noise , but with the new belt back on the noise is back, does that mean a bearing on one of the pulleys has gone? i couldn't feel anything on them. it can't be the crank as that would have been moving with the belt off anyway.

Click to expand...

Probably a duff bearing yes - the idler(s) (depending if you AC/ACE etc) can be replaced relatively cheaply - gets a bit more complicated if it's one of the other pulleys...

Thanks I had another look , but I can't work out which one it is , I've got ace and ac . I could do with a shorter belt to miss a pulley out each time .

Have you tried taking the belt off and spinning the pulleys by hand/seeing if they have play?

Yes they all seem ok , but belt off and the noise is gone

checked again , is the ace pulley supposed to be stiff to turn?