The car makes a humming noise and won't start

[Ayse]

I am writing about a car that made a long buzzing noise.
Two days ago, we pulled over in front of a store and my friend got out of the car, and when I attempted to start the car again to park it a few blocks further, the car would not start, and the engine started to make a humming, buzzing noise. The noise would not stop and we called a towing truck. The car continued to make the noise for 45 minutes until the towing truck driver disconnected the battery. We also would smell a burn with increasing intensity, and about 20 minutes or so in making the noise, there would also be some clicking noises.
The repair shop says the car runs just fine now, that it is not making any noise, and they have no idea what the problem may be. About a month ago, the timing belt broke and the repair shop had to rebuild the engine. And occasionally we would hear a humming noise when driving the car. I suspect that during the repair the repairshop made a mistake.
This is the recording of the sound.
Do you have any idea what the issue may be?

 

[C1]

Stuck electric cooling fan motor?

 

[Ayse]

Thanks for your reply. This can explain the noise. Do you think that could be the reason why it would not start as well?

 

[Ayse]

Here is the sound if it is of any help.

 

[BarkingGhostar]

With the battery disconnected, disconnect the starter motor hot cable. Now reconnect the battery and see if the noise continues.

 

[Ayse]

I am not sure if that is what the repair shop technicians did, but they say after they reconnected the battery the noise was not there so they can't figure out what happened.
My worry is without knowing what went wrong, the issue can repeat itself and I don't want to pay for another towing fee. And it is hard to know when it will happen again. Do you have any idea what may be the source of the problem?

 

[mindless1]

Diagnosing fan is easy enough, simply unplug it, then don't forget to plug it back in before further use, or if it's on a fused circuit with nothing else critical on that circuit, pull the fuse.

A bad bearing on something belt driven can also make a similar sound, and there you would pull the belt off then start the engine to see if the sound stops and while off, check all pulley driven things, the idler/tensioner for excess play or rough spinning. Don't run the engine long this way since you may have a belt driven water pump and the alternator too.

If it's the A/C compressor you can just turn all HVAC off and look at it to make sure the clutch disengaged it, though there is still the clutch bearing itself which gets covered by taking the belt off.

 

[Ayse]

Thanks so much for the suggestions. I will communicate these with the technician. But because the noise is gone now, they find it difficult to test what the cause was, I believe.

 

[mindless1]

When the car wouldn't start was it cranking (seeming to spin) at normal speed? If not, I would measure battery voltage (might have been low due to cold weather and in conjunction with a low charge level was not enough to start the engine).

If that's the case then my first suspect would be the alternator, though it is odd it then began working again, intermittent faults can be a PITA, especially if you have to depend on using the vehicle and don't want to risk getting towed again, which can cost as much as a new battery or alternator (depending on where you shop and if you DIY).

 

[Ayse]

When the car wouldn't start was it cranking (seeming to spin) at normal speed? If not, I would measure battery voltage (might have been low due to cold weather and in conjunction with a low charge level was not enough to start the engine).

If that's the case then my first suspect would be the alternator, though it is odd it then began working again, intermittent faults can be a PITA, especially if you have to depend on using the vehicle and don't want to risk getting towed again, which can cost as much as a new battery or alternator (depending on where you shop and if you DIY).

Thanks so much for your response. The battery is quite new, and we live in Vancouver, BC, so the temperatures are very mild. The car was not cranking at all when I tried to start the car while the engine was making all the buzzing/humming noise.