Cooling Fan Issues

[Crow911]

Started car up the other morning and heard funny noise—ping, ping, etc. Drove to the office the home. Pulling into driveway and the noise was loud. Opened her up while idling in the garage and immediately diagnosed sound coming from cooling fan which was hitting the shroud. Took belt off and confirmed not play in alternator shaft. Reinstalled belt one sim loose and sound went away. Drove to office next day without noise but on way home noise returned. Took out fan, shroud, and alternator today. Confirmed no play in alternator shaft but discovered the fan was bent. New fan on order. Other than age (38 years old) what would cause this?

[Crow911]

[Crow911]

[Trippyloaf]

Check the housing for cracks, causing it to be out of round.

[Crow911]

When I replaced the alternator about 10 years ago my magnesium shroud was cracked. I replaced it with an aluminum one and it is still perfect.

[Flat6pac]

You have to balance the fan in the housing adjusting the 3 through bolts on alternator to center the fan.
The other 3 through bolts holding the extension need to be snug but not as tight as the ones used to center the fan
Bruce

[Crow911]

When I replaced the alternator about 10 years ago my magnesium shroud was cracked. I replaced it with an aluminum one and it is still perfect.

[gled49]

Looks like an electrolysis corrosion fungus growth distorting the fan from the hub. That’s a new one on me.

[gamin]

Aluminum fan and housing is the way to go.

[Crow911]

Decided to drill out rivets to see if distortion in fan could be corrected with some soft mallet convincing. No joy. most of the fan returned to original location, but developed a chunk of magnesium which separated from fan leaving a small hole. Now the fan will be worked with filler, painted and converted to clock with appropriar nut.

[911obgyn]

Looks terminal🥺
I wonder if the paint or coating trapped moisture?
When i rebuilt my alternator i spent an hour or so on the fan with a scotchbite pad then coated it with ACF50, re applying it every year. Supposed to keep corrosion from getting into the magnesium.

[Shaun @ Tru6]

It's very dirty and the image is small so hard to zoom in, but those rivet heads don't look original. What do they look like underneath?

Of the 200+ fans and housings I've restored, I've seen 3 or 4 where the machined ring for the hub cracks around the perimeter and the fan is toast. This looks like that. Have also seen plenty where the balancing holes from the factory have very early gone through the fan top side perimeter ring.

[Crow911]

they protruded through the hole and were slightly rounded on the end. I drilled them out and they were aluminum. No evidence of being anything but original.