96 Passat Turbine-Like Whine

I’ve got a 1996 VW Passat GLX VR6 with about 111K miles on it. Recently, after I started the car, I heard a loud, turbine-like whine coming from the engine. It disappeared after a few minutes/miles; but later when I started the car cold again it re-appeared. It continued for a few seconds (5-10) even after I turned the engine off, then winding down.

I looked under the engine and saw a small plastic hose just behind the radiator that came loose, so I reconnected that and it didn’t make the sound anymore. This was about a week or so ago.

Now yesterday it started back up. Once again, it only lasted about a minute. I suspect it might be the starter not disengaging after the engine is running. But before I take it to the shop, does anyone have any ideas on what might be causing the problem?

I can post links to pictures of the hose I reconnected, or a video of the engine whine if that would help. I might just crawl under the car and bang the starter with a mallet to see if that stops the noise, at least then I would know what the problem is. But if anyone has any better suggestions, I would be grateful!

Cheers! M2

My guess - an afterun water pump that is running all the time, not just after the engine is shut off. It could also be a fan going bad.

Good luck - I rather doubt it’s the starter as I would think it would have failed rather quickly if it had to run with the engine the full time.

The noise you are hearing is the aux air pump.
The hose you re-connected is coming from or going to the pump. (The pump itself is behind the radiator just under the intake manifold.)
I’m not sure what’s causing the pump to make the noise (it’s going bad, maybe).
The mechanic should be able to track down the cause quickly.