Two things common to this.
1. In warmer weather, you will see the fans locking up a little more, this is normal and will cause a noise.
2. The front bearing bracket will fail on these and cause a noise, however, it usually will not go away.

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Benzmac:
Donnie Drummonds
1992 500E (very soon I hope
1981 280GE SWB
ASE CERTIFIED MASTER AUTO TECHNICIAN
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