tangram

I had work done on my '95 993 coupe this past winter that required dropping the engine. Since I've had the car back I've driven the car about 1,000 miles and have shredded two belts on two separate occasions. My conclusion is that the work done on the car has resulted in this problem but I would like input on what could be causing this prior to my next discussion with my mechanic.

In the case of last night's incident, the belt breaking was preceded by two instances where the belt could be hear to be slipping. The belt in question is the one that is closest to the back of the engine compartment.

Thanks.

Stealth 993

1st make sure the fan housing is seated properly, & the belts are not at any kind of angle.
2nd make sure the belts are not under/over tensioned.

tangram

The problem according to the mechanic is that the belt was slightly too wide. Apparently up until recently Continental was making belts that were within spec. The shredded belt was too wide. Also, I guess there was an early 993 service bulletin that recommended new pulleys (mine is a July '94 build date so qualifies as "early"). So we will see how things go. I have OEM belts installed now.

BobbyT

I have had best results using only the genuine Porsche belts. The correct part numbers for the 1995 are (inner) part# 999 192 338 50, (outer) part# 999 192 343 50, and (AC) part# 999 192 363 50.

There is also a pulley update. This is for the outermost pulley on the alternator. The factory-installed pulley halves are thinner than the replacements. The original ones can break, and the pieces can dent the engine lid. The new pulley part number is 993-106-268-01, two required.

Text from Porsche Tech Service Bulletin: When installing the new version pulley halves on the 911 Carrera and Turbo, the distance spacer is machined as part of the new version pulley and is no longer required. Because of this, it is no longer possible to store adjustment shims behind the distance spacer on the outside of the alternator pulley. Shims removed during the tensioning procedure should be stored in the vehicle tool kit.

I think it is critical to get the tension of the belts just right. Too much slack and the belts slip, too tight and the cord in the belts begins to fray along the edges. Too much tension may also lead to premature bearing failure. The belt tension gauge is very expensive from Porsche, but under $10 from Napa Auto Parts, sold as "Crikit belt tension gauge".

mhm993

Dont know why, but my car throws conti belts very quickly after installation, but never factory. Saw another car do the same, at the track today.