screeching sound when cold start

[tlkchew]

E46 318i FL model.
Every morning or when cold start, i hear this screeching sound.. something like the starter motor over cranking for about 1-1.5secs after engine is started.

anyone experience this before?

warm engine seems fine.

Cheers

 

[centurion]

Re: screeching sound when cold start

drive belt koyak. Probably alternator drive belt. But if your car has extensive serpentine belt, you just have one thing to change. when you start your car, the alternator has a big load trying to charge the battery, and has big resistance. If the belt is not tight enough, the alternator pulley is slipping hence the sound.

You may also have the sound when you turn your car hard, loading the Power steering pump.

 

[tlkchew]

Re: screeching sound when cold start

Oh Ok.. Thanks for the information, another "bomb" coming hehe..
better get it changed before i cannot start. hopefully it can last till the next 10k servicing. which is another 8k more!

 

[centurion]

Re: screeching sound when cold start

30K replacement interval lah, typically.

 

[R2D]

Re: screeching sound when cold start

Actually the belt is not always the problem, most of the cars that we've seen have the same problem. Can be traced to a worn tensioner bearing and also idle pully bearings. The N42 engine uses a loooong belt to go round all the ancillaries. (air con compressor, power steering pump.... BMW chose to wrap the belt around each pully and the typical contact patch is around 180 degrees around the pully.

most of the time its the pullies...

Dun worry it is a relatively fast fix (about 20mins) and really quite cheap..

 

[centurion]

Re: screeching sound when cold start

yes. the main issue is belt tension insufficient, so the tensioners if poorly designed can be a cause of this too.

Anyway, check out your mileage, if it justifies, even if the belt not at fault still can change.

 

[tlkchew]

Re: screeching sound when cold start

kewl! whats the life span of the belt, i think my next change requires that as as well. i'll check the stiff nees of it.. and get it swapped out...