Rumbling noise from late 2013 21.5: iMac

From your description of the problem it would seem the noise is originating from an exhaust fan, which may be worn or contaminated with debris.

Have Apple evaluate it. Use the https://www.apple.com/support/contact/ link to find authorized service in your area.

Replacement, if required, is not particularly difficult or expensive.

They're right next to each other, so it could be the hard disk drive. It's not as inexpensive to replace that part, but certainly not one of those "uneconomical to repair" items though. Once the Mac is disassembled replacement is easy.

Back up your Mac if you have not done so already. To learn how to do that read https://www.apple.com/support/backup/. To learn how to use Time Machine read Use Time Machine to back up or restore your Mac.

You might be able to use Apple Hardware Test to either correlate the noise with fan activity, or eliminate it as the cause. Apple Hardware Test is for Macs produced prior to June, 2013. Later Macs use Apple Diagnostics.

Steve-999 wrote:

A few months ago I became aware of a rumbling sound. At first I thought it was distant thunder and ignored it, but after the noise continued for a few weeks I realised it was from the computer, a late 2013 model 21.5" iMac.

The noise is intermittent and not heard every day but certainly most days. It 'rumbles' for a couple of mins then stops for some time before doing it again. It appears to be from the rear left (as I look at the screen).

Any ideas / suggestions would be appreciated.

Thanks.

Have you used the diskdoctor (utilities menu) to see if the disk is going.

On my power mac- the rumbling was the disk -- and the message showed in disk doctor without having to test the drive (make sure you look at the drive-not just the tabbed in part).

A rumbling noise that you might mistake for thunder probably isn’t the hard drive but to be sure you should run the Disk Utility program to check it out. Drives tend to click or when they are in great distress, squeal. (That is something you don’t want to hear and you won’t hear it for long!) A rumble would more typically be the fan blade hitting the housing because dust has accreted on one blade more than the other so it is unbalanced. It might also be the speaker and quickly tested by changing the volume.

By the way I recommend you do not use any so-called disk "doctors", "medics", "cleaners", "experts" or similarly ill-conceived non-Apple garbage to do anything whatsoever with your Mac. Those things are not only worthless, using them will accelerate a hard disk drive's eventual demise. All you need is a reliable backup strategy, in preparation for that inevitable event. A hard disk that has failed should be discarded, with its replacement's contents restored from the backup.

Steve-999 wrote:

Thanks.

I have just run Disk Utility and carried out First Aid on the internal HDD. The report showed no problems. 🙂

Is it distant thunder -- my Power Mac did not have an internal fan (G4Cube) and a rumble - did over time turn into a failing hard drive.

Did not have enough RAM for what I was working on in Photoshop and could not upgrade same so too much swapping was the issue.

So keep an eye on the drive - as I kept checking it and didn't get the failing message right away.