Hi all,
I have a classic MY99 Impreza Sti. Done about 86k. Recently I noticed that when I switch off the engine, there is about 1-2 seconds of whirring coming from the engine bay.

Done some diagnostics myself, removed aux. belts and it's not PS pump/alternator/AC. I'm leaning towards starter motor? No lights on dash and otherwise good as gold. Doesn't sound muffled like I'd expect a water pump to be.

It whirrs longer if the engine is warm, maybe 2 seconds after the engine is quiet and only half to 1 second on a cold engine.

Any advice on further diagnostics?

Cheers in advance

 

turbo spinning down with loud bearings?

 

Oh! completely forgot about the turbo! That's a good shout. Any ideas how to test that theory?

 

It's almost certainly the turbo, and when you can hear it very plainly (rather than a soft whisper with the bonnet open) then chances are the bearings are on the way out.

 

Ah okay, do turbos get rebuilt these days or do we just buy new ones?