[Vwdiesel] 02 TDI, faint tapping when under load

[Doyt W. Echelberger]

How about nominating a serpentine belt itself as the source of the faint 
tapping?  Perhaps a frayed cord that is slapping a belt cover as it goes 
around? The belt is geared to a different rpm pattern than the engine by 
the pulley system of which it is a moving part. Or, perhaps something run 
by a belt, such as an alternator or an AC compressor?

Or, maybe some rotating component of a wheel, such as a wheel cover, or CV 
joint, or CV joint cover.

Doyt
playing the late innings of this guessing game
/>>>>>>>>>>>>>>>>>>>
>On Dec 18, 2011, at 6:52 PM, Stephen Sherman wrote:
>
> > My new to me 02 Jetta TDI has a faint tapping noise which has me 
> concerned. I've had a few people listen to it, and opinions vary, some 
> thinking it is in the dash, others (including me) thinking it is coming 
> from the engine or drivetrain.
> >
> > Symptoms are that when the engine is under load, accelerating or going 
> up hill, there is a faint tap, tap tap noise.  If you let up on the go 
> pedal, the tapping stops immediately (so it doesn't seem like it could be 
> wheel/tire related), and resumes as soon as you push on the pedal 
> again.  It does not tap if you just have it in neutral and rev the 
> engine, no load.  The frequency of the tapping varies a bit but is 
> generally in the 5-10 taps per second range (just rough counting here). 
> I've tried to notice if it changes frequency around gear shifts (auto 
> tranny) but have not gotten anything conclusive.
> >
> > I have tried listening with a mechanics stethoscope, but did not hear 
> anything that seem to be it (again doesn't tap when not under load. I 
> have checked the CV joints, and no obvious play in any of them.
> >
> > Any other things to check out? Ideas on what it might be?
> >
> > TIA
> >
> >
> >
> >