Centurion --- noisy fan ??

[Rooster]

My 1971 Centurion blower fan sometimes makes a loud humming / harmonic noise.

Lasts for a few minutes ( or longer sometimes) then goes away. First thought bearings in fan motor so took out and lubed them. Noise still there , only changing pitch slightly when put on fast speed which leads me to nothing wrong with motor. An ideas please. Ken.

[NTX5467]

When the "hummm" goes away (in whatever fan speed), does the air output from the vents increase or stay the same? Does the "hummm" return each time the fan is turned on or just the initial time it is used? Did you check for "end play" in the fan motor when you had it out? What method did you use to lube the bearings in the motor?

Sometimes, such a harmonic vibration might indicate a certain amount of imbalance in the impeller or total rotation assembly of the motor/impeller assembly. As you note the sound comes and then goes, that might not completely be the case.

Enjoy!

NTX5467

[Pete Phillips]

Is the noise coming from the fan or the water pump? Have you tried removing the fan and running the car for a few minutes without it, to see if it might be a noisy water pump?

Another suggestion: I once had a '56 Special that I thought had a noisy water pump (was more of a clanking noise than a hum). After buying and installing 3 water pumps in the space of two weeks(and raising the hackles of the local auto parts store when I kept returning them as "defective"), I finally discovered that the problem was a hairline crack in the fan pulley!

Pete Phillips, BCA #7338

Sherman, TX

[Rooster]

The noise generally starts when the ignition is first turned on, although sometimes during operation. I did not check end play , used oil on the bronze bushes. I have given the motor a thump during the noise phase and this stops it. Could blade assembly be slipping on shaft ?

Ken.

[Smartin]

Might be time to replace it..

[Rooster]

I've just pulled out the fan and found one of the end bushes was binding up. Apparently none of the lube I put in found it's way to where it should have --- my fault ! Put back in and no noise , BUT !!!! now can't get hood to line up between rubber buffers and sit down at windscreen end ??

Ken.