ENGINE DOES NOT CRANK.Flywheel problem

[muneeb]

Hi guys,
I have 2005 LTZ Lumina.Problem started all of a suddent with no previous history.I am trying to start Engine but when i push the key a "tak,tak,tak" sound comes from downside engine and it does not crank and "SVS" message appears in message center.I switch off key and On it again then, during system check it says OK but when i start,same problem.I brought a mechanic, he removed Starter motor,rotated slightly the Flywheel and then fixed back the motor.Car is starting normally.As per him,some part of Flywheel is damaged(some sharp teeth,which are rotated with starter motor during crank of fly wheel maybe) and when they are in a position aligned with starter motor,Car is not starting.
I doubt in his statement,can anyone give any idea what could went wrong all of a sudden??

[Sabbath']

Broken flywheel teeth?

Except for the problem when it rotates back to the same spot. And you're in the same predicament. Probably will need a new flywheel at some stage.

[muneeb]

A Broken Flywheel..

This is what my mechanic has to say,But i want to know does it happen rarely??I believe flywheel is a solid IRON wheel and it should not be possible that it breaks like that.Although he is replacing it with the new flywheel, but i doubt how it is broken...

[Sabbath']

It does, and can happen.



So you're up for a new flywheel/flexplate.

[muneeb]

Dear
From the deepest of my heart, i am thankful to you for your detailed help.
One thing more.When my car is parked on unsmoooth road and i shift gear from P to R of D,it gives me a message" HILL DESCENT CONTROL OFF" with a car symbol.I want to know how this function works and how i can operate it?