Alternator on its way out?
Discussion
Car's a 1990 Astra 1.4 petrol 
For a few months I've heard a whining sound when idling, but only when cold (as I thought - only just worked out that it's cold when dark, and when I have lights on...). Traced it to the alternator and thought nothing of it. The other day a mechanically-minded mate was in the car and commented on it, I said it was from the alternator, and he said it was probably a bearing. Anyway, approximately 10 seconds after dropping him home it starts rattling. b
d. Got back home and put on my rear foglights, noticed the rattling started again. Turned off all lights/heater etc and it stopped. Everything back on, and both whining and rattling started, both coming from the alternator.
This is intermittent though
And I've not heard the rattling since, just the whining. Any ideas from the PH masses what could be the issue?
Cheers
For a few months I've heard a whining sound when idling, but only when cold (as I thought - only just worked out that it's cold when dark, and when I have lights on...). Traced it to the alternator and thought nothing of it. The other day a mechanically-minded mate was in the car and commented on it, I said it was from the alternator, and he said it was probably a bearing. Anyway, approximately 10 seconds after dropping him home it starts rattling. b
d. Got back home and put on my rear foglights, noticed the rattling started again. Turned off all lights/heater etc and it stopped. Everything back on, and both whining and rattling started, both coming from the alternator.This is intermittent though
And I've not heard the rattling since, just the whining. Any ideas from the PH masses what could be the issue? Cheers
P I Staker said:
Hard to know without hearing it.
From how you describe it, could be alternator as you say, or a tensioner.
The alternator is constantly driven when the engine is running so from the sounds of it the noise coming and going was coincidence with you pressing buttons.
I'd be surprised if it was coincidence; probably did it 5 or 6 times. The more things on, the louder it was. From how you describe it, could be alternator as you say, or a tensioner.
The alternator is constantly driven when the engine is running so from the sounds of it the noise coming and going was coincidence with you pressing buttons.
The only way I can describe the whining is like when an old bus or lorry stops, but softer. Same sort of noise
P I Staker said:
The alternator is constantly driven when the engine is running so from the sounds of it the noise coming and going was coincidence with you pressing buttons.
It is but the electrical load and therefore load on the bearings, tension in the belt etc. varies depending on what you have switched on. Ever noticed a slight drop in engine revs at idle when you switch the lights on?Op, sounds like either a tensioner or the alternator itself. I'd just drive it until it gives up but then I do like getting into a muddle.
busta said:
It is but the electrical load and therefore load on the bearings, tension in the belt etc. varies depending on what you have switched on. Ever noticed a slight drop in engine revs at idle when you switch the lights on?
When you put it like that, it makes perfect sence. Thanks. P I Staker said:
busta said:
It is but the electrical load and therefore load on the bearings, tension in the belt etc. varies depending on what you have switched on. Ever noticed a slight drop in engine revs at idle when you switch the lights on?
When you put it like that, it makes perfect sence. Thanks. To make things more confusing, some modern cars only switch the alternator on when you are slowing down.
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