Just noticed I have a loud hissing sound coming from driver side front of the engine bay. It sounds like it's near to the alternator. When I turn of the engine it continues for a second almost like something depressurising. Anything to worry about? Car is having some work done this weekend so might as well add it to the list.

On 20/03/2015 at 16:37, Nikonite said:

Just noticed I have a loud hissing sound coming from driver side front of the engine bay. It sounds like it's near to the alternator. When I turn of the engine it continues for a second almost like something depressurising. Anything to worry about? Car is having some work done this weekend so might as well add it to the list.

 

hi, did you ever found out what the issue was? i'm experiencing the same. 

@Bertie90

 

5 year old post!

Overwintering snake?

Sprag clutch bearing AKA the one way clutch bearing in the alternator pulley.

 

When the engine stops the pulley stops but the alternator continues turning until its inertia is lost through the bearings.

 

While still fully functional they will start to make a hissing noise on engine shutdown and as they get worse there will be noises and snatching of the aux drive belt when running.

Edited 8 February, 20206 yr by J.R.