RE: Whirring Sound - not good
 

If you noticed, MANY mechanices (porsche trained and dealers themselves) install new belts at 4.0 for both timing and balance shaft. Only the 944 mechanics (or the ones who know their way around them) know the little bits and pieces that the manual specifies.


Worse case scenario of over tightening balance shaft belts? amazingly rought idle with a jet-engine sound comming from the engine, along with a smoking exhaust, balance shaft bridges chatter (yes they get noisy) and the whole car shakes like an LA earthquake hitting 10+ on the scale (if it ever did :p) That was the case done on my 88 NA (RIP) and turned out that the factory tool was out of calibration and the belts were on a 5.6 if i recall. Which is extremely over the limit.

BUt even now when i tell then, call them and fax them regarding tensioning the belts, they seem ok with the timming, but still have a ~3.0 on the balance shaft belt (which is acceptable since the manual specifies 2.7 +- 0/3 i believe).

RE: Whirring Sound - not good
 

Check the tension on the belts. Sounds like they may be too tight. The manual says to set them to 2.7. This is a setting for a new belt. As the belt is worn, it will stretch a bit. Keep in mind that the tension must be checked at 1500 miles, and then again at 15K. If they sound too tight, back them off a bit. When tight, the balance shaft belt will feel LOOSE. You can easily turn it 270 degrees from the middle of the run from lower to upper shaft.