Volkswagen Repair: 2002 Jetta 1.8T 5/spd man / MIL Light, water pump impeller, impeller blades


Question
Ever since I got this car in 2006, the MIL light comes one from time to time.  (Engine with a lightning bolt)

When the light is on.. there is a distinct 'back whine' noise at starting.  Sounds like a turbo malfunction or something.  You can get that *sometimes* even when the light is off.

I've tried everything.  No codes are stored.  Dealer at a loss can't find the problem.

I tried switching fuel brands, adding octane boost .. whatever.

Recently, I topped up the coolant and the light went out immediately and stayed off for almost 3 weeks.  Now today, it came back on .. even tho coolant level hasn't changed.

Extremely frustrating.  Any ideas?

Answer
John,
 One thing I can say is that a MIL light should get you a code in the computer.  Why the dealer can't see this is beyond me.  However the whine may actually be the cooing water pump; the cooling systems on some VW models are known to get "gunky" and need to be flushed and refilled with proper VW approved coolant.  Also some water pump impeller blades are plastic, and sometimes break a blade, which can cause noisy operation.

Rick