Volkswagen Repair: MKIV Golf, starter, fly wheel, golf gl

Question
Hi,

I have a 2000 Golf GL with a 2.0 L engine.  170 000 km.  No major repairs on the engine or car in general.

I have had to replace the starter twice in the last couple of years.  When it started to go bad, starting cold (and in cold weather) would produce a whirring noise.  According to my VW mechanic (independent, not a dealership), the starter was sticking in the engine as it turned over and was forcing the starter gear/arm (not sure what it is really called) out, causing the noise.  

However, the noise has started again, after it was replaced a year ago.  Am I just receiving faulty replacement (re-built) starters or is there something more to this?  I believe the last time, they filed the teeth on the fly wheel (or whatever the starter engages in the engine, as they noticed some burrs) that may have been causing the starter arm to not release correctly.

After starting it and running for a while, it will not make the same noise until the next morning.

Otherwise, the engine runs fine.

thanks

Answer
Arnold,
 As you probably understand, the starter gear must be engaged only when starting, and then released.  Now, the release is accomplished by the key being released, which de-energizes the solenoid(mounted to the starter) and then a built-in return spring pulls the starter gear away from the engine flywheel.  So given this scenario, either:
- The signal from the key is constant.
- The solenoid is stuck.
- The starter gear is stuck.
- The starter gear return spring is broken.

The first is unlikely.  For all the others, the starter is bad.  Why? Well, cheap or poorly rebuilt starters can go bad prematurely.  And if the starter gear does not release, this causes to starter to spin at engine speed the whole time your are driving, which it is definitely not designed to do, and can very well be expected to fail prematurely.

I have never hear of a chipped/burred flywheel "making" the starter gear get stuck and not release, it seems physically impossible if the starter is not already broken.  However, bad teeth on the flywheel (or the starter) could cause the starter to "grind" or "whirr".  At first the grinding will be occasional, but the more it happens, the worse it will get as it wears the teeth of both the starter and the flywheel.  If there are enough bad teeth on the flywheel, then obviously replacing the starter may not be enough, but the flywheel will have to be replaced.
 I would have the starter removed and have all the flywheel teeth inspected closely.  Then make sure you get a quality replacement starter.
- Rick