No idea what it is(85 Brat). But, it made it this morning, and yesterday, when it was very cold out, and the car was still very cold. Sounds like it's coming from under the hood on the driver's side, and kind of makes a whirring sound. Didn't seem to be related to vehicle or engine speed though. Made the sound for a few seconds, then stopped. Then did it again later, and so on. Seemed to completely stop after the car was good and warmed up.

 

Any thoughts?

Alternator is a good bet. Cold grease in the bearings, so they make noise. Having to charge the battery to make up for the starting draw might be a factor, as well. Mine does it too. It is a cheap rebuild, so my bet is on the bearings. Are you sure it wasn't engine speed related? Is there any other motor that starts running with the car, and would have cold bearings?

 

Rob.

Edited December 10, 200916 yr by robm

+1 on the alternator. Idler pulleys and distributors do this too.

Alternator is a good bet. Cold grease in the bearings, so they make noise. Having to charge the battery to make up for the starting draw might be a factor, as well. Mine does it too. It is a cheap rebuild, so my bet is on the bearings. Are you sure it wasn't engine speed related? Is there any other motor that starts running with the car, and would have cold bearings?

 

Rob.

 

Short answer: No, I'm not sure.

 

It happened fairly quickly, and it's very faint if I have the radio on. So a few times I didn't catch it until about 1 second before it went away, making it hard to determine for certain if it was or was not engine/vehicle speed related. But it didn't do it today, as it was above 20F outside when I went to use the car. Seems to be a <5-10F problem.

I had an ea81 hatch do this, it was the worn distributor bushings. Only when it was very cold, the shaft would chatter, once warmed up it would stop. Is there any play in the distributor shaft? Does your tach jump around when the noise is there? I remember it being a screeching chatter, not a rolling whirr. A whir like bearing noise would suggest the alternator, or maybe the idler pulley(s). At least to start with anyways .

 

Does your brat have AC? Sometimes the clutch will wear and the pulley will chatter and sound like a bell, or alarm clock.

I had an ea81 hatch do this, it was the worn distributor bushings. Only when it was very cold, the shaft would chatter, once warmed up it would stop. Is there any play in the distributor shaft? Does your tach jump around when the noise is there? I remember it being a screeching chatter, not a rolling whirr. A whir like bearing noise would suggest the alternator, or maybe the idler pulley(s). At least to start with anyways .

 

Does your brat have AC? Sometimes the clutch will wear and the pulley will chatter and sound like a bell, or alarm clock.

 

It does have AC, but there is no belt on it.

 

To my knowledge, there is no play in the distributor, but I haven't checked it lately. And I did not notice the tach moving around at all.