Luis de Prat

As far as I know, I tensioned both belts to the "ideal" settings using the Arnnworx P920X taking care to snap the gauge repeatedly for an accurate reading. I'm not getting any other vibration from the engine except for this momentary "scraping" sound.

Mark944na86

If it were me, since the noise is coming from the front, I'd pull the covers off to double check everything and to make sure nothing's come loose that shouldn't have, e.g. a roller is coming loose (I'm not saying it is likely, just that I'd stay awake thinking about the possibility until i'd checked it.)

Luis de Prat

That's a thought, but I don't understand why would it not manifest itself revving at idle. It only does this in gear.

jstand22

Actually a slightly incorrectly tensioned or misaligned balance belt is usually only apparent at like 2,500 rpms - 3,200 rpms.

But maybe it is a heat shield somewhere? The one over the cat maybe?

Luis de Prat

Really? There's a guy in the 968 forum who just found out he had no balance belt on his car and he could never tell from driving it.

I find it hard to believe that tensioning the belt to the ideal setting with the Arnnworx tool I'd be worse off than by setting the tension by feel like most people do with the balance belt, but I guess it's a possibility.

The sound is just too metallic to make me think of a belt. I also conscientiously tightened each idler, roller and sprocket to 45 Nm with a torque wrench.

Makis

The balance shafts do not remove completely all the engine vibration it just suppresses them. Some vibration modes do eventually cause some rattles as the car milages increases as car bits loosen up. I have driven my car without the balance shaft belt connected at the engine feels quite buzzy. If I drive it like that lots of rattles will appear in time. I get even worse results if the shafts are not alligned correctly. Also I expect the balance shafts are less effective on the S2 3.0 liter engine then on the standard 2.5 liter engine because of the extra capacity.

jstand22

I'm not saying that's what it is, just suggesting, but if I were you I'd go with your gut....Is it more of a noise? Or a vibration? check the clearances on the heat shields on the car, one may be rattling against something....Also check the belts anyways for alignment or a loose roller (easy). Maybe take a video and post it up and maybe someone will hear it and know. Maybe the torque tube bearings have had it.