Intermittent Grinding Noise

[stutto 0]

I have been getting an intermittent grinding noise, occuring during the early part of some journeys (so far only once per journey). Today when it happened I saw the battery light come on. It has only happened when turning left or shortly after, although this may be coincidence as I take two lefts in quick succession when I leave work.

 

My thinking is that an alternator bearing is on its way out, and that it may be happening when the revs rise above 3k for the first time. At idle the alternator does sound a bit noisy.

 

Does this sound right or could I replace it only to find out that it is the water pump? (I've not noticed high coolant temps or coolant loss).

[cir287 0]

sounds like its probably the altenator alright, if water temp is ok and no coolant loss then water pump is most likely ok.

you could try loosen the altenator belt and see if there is any play in the pulley/shaft, even if this seems ok it could still be fault.

one way to find it is to leave it get worse till you can definately identify, but you may be left stranded if the altenator packs up, water pump may also stop.

 

probably best to get altenator checked out sooner

just my opinion

[aCe 0]

One way to eliminate the Alternator would be to disconnect the alternator poly v belt all together and run it up for a short period (There is enough energy in the battery to run the car for probably around 20mins). You don't have to do it for long but straight away you shoul;d be able to tell if the noise is gone- If it has then its something on the poly v belt sequence, if not cambelt area?

 

Hope that helps, good luck

[stutto 0]

Thanks for the replies.

 

The problem with disconnecting the belt is that it does not happen every journey and so far has only happened once per journey. May have to disconnect it just to see if that quietens the noise from the engine bay at idle.

[unariciflocos 49 1 Cars]

Drove my 405 for 50 miles with no alternator and headlights (had no choice, alternator fried in the mountains at night) so you could try a short run with no alternator belt.

[stutto 0]

Well I replaced the alternator yesterday afternoon, the old one had play in the shaft plus there was something rattling around inside.

 

Better now than waiting for complete failure, although the noise hadn't repeated since I started this thread.