grwoolf

I have a 97 with the original pulley and did not replace it when I changed out the belts. Based on the service records on my car, it threw a few belts when brand new and they replaced the original pulley halves under warrenty with another original-style pulley (before the new pulley was released). The car has not had a belt problem since. I figured the old pulley style is hit or miss whether you will have a problem. The pulley tsb wasn't a recall, just an update for those having a problems. If I ever have a belt problem, I would do the pulley update.

Edward

Grant raises an interesting point: is said TSB a "mandate" or simply a replacement for those experiencing issues? FWIW, I now have 122K or thereabouts on the orig pulley. Am I on borrowed time waiting for a pully to grenade, or is all well and good if it has been well and good thus far? In the three belt changes I have personally done so far, I saw no evidence if issues ...and truth be told if I had remembered at the time, I would have gotten the update, but since I didn't remember to order the new pully and already had belt in hand...you know how that goes

All the talk always gets me nervous as this "pulley thread" comes up regularly. But if it ain't broken ...well. Maybe next belt change I'll do it ...or sooner if it does grenade.

Edward

viperbob

The older pulley was still used up through '97. The TSB is a highly recommended modification (if it was a recall, then Porsche would have to pay for it).

IXLR8

I just replaced all three belts; fan, alternator and air conditioning.

Even my 760 mm belt was too tight, and that is with two shims between the pulley halves. I will be ordering some extra shims.

I took it for a short 2 mile drive to seat the belts (just running it in the garage did that) and when I got back, the alternator pulley was very hot to the touch. For comparison, the fan pulley was just above ambient temperature...or warm. I can't see the heat being generated due to belt slip on a belt that is too tight to start off with.

As for the AC belt, the Porsche parts catalog has it at a 12.5 x 1085, yet the one I got from Porsche is 13 x 1085 (same part number: 999 192 363 50). That would explain why it was tight with the compressor fully towards the loose side of the slots; in fact with the belt on, the compressor needed to be drawn down by the three bolts for it to seat in its mount.

Getting to that AC adjuster locknut... I ended up having to buy a offset box end wrench. Why Porsche didn't use a threaded collar with built in nut...

David in LA

Is the pulley update/TSB also applicable to Turbos, or just NA 993s. Is there a final determination of what year cars this covers?

geolab

This TSB is for both, but there is something peculiar about it.
if you read it quickly, you would order the new pulley and new belts, ASK ME HOW I KNOW.
even Chris and many others read it quickly

The new sized belt is for Turbo only.
so for carrera, same 76 cm belt.

for info belts for the outside pulley existed in:

9.5 x 75.3
9.5 x 75.7
9.5 x 76
9.5 x 77.6

this belt is one of the very few pieces that differentiate between a manual gearbox ROW engine and a tiptronic ROW engine if engine is nude without flywheel or bell housing on the back.

IXLR8

The numbers you quoted would be in centimeters (cm). All my Porsche belts are sized in millimeters (mm).

Add a zero or move the decimal over one place. ie 75.7 would be a 757 mm belt and 76 would be a 760 mm belt.

geolab

yes centimeters

I will have to google this, I am not sure.

IXLR8

Trust me, I am.

The belts are labeled as 9.5 x 760....the 9.5 is in millimeters as is the 760.

If you were dealing in centimeters, then you would need to change the 9.5 to 0.95.

Thats the beauty of the metric system, you can just move the decimal over to go from centimeters to millimeters. Try that with the foot/inch system.

chris walrod

I must have read it quickly, but so did the dealer I ordered my first pulley update kit -- they too sent the 757mm belt/

geolab

Alex Stop it. I was kidding, yes yes you are right.
I am in metricland,
TBH , nobody says seven hundred and sixty millimeters here in europe.
Its like saying seven hundred and sixty cents, bit odd.
That is where my commas came from, nature...

IXLR8

You mean in France...they are different there.

The belts I got from Porsche are made by DAYCO in Italy (so were the old ones that came off the car) and the outer edge lists...millimeters.

I'm going to check for a source of alternate sizes. The Porsche supplied AC belt is too short. It is labeled 13 x 1085 millimeters. The Porsche parts catalog says its a 12.5 x 1085 (go figure) which would make it longer since it rides lower in each pulley.

2Many Cars

I wouldn't want to run it much with a too tight belt because it'll kill the alternator bearings in fairly short order.

TheOtherEric

Lol, yeah, they don't tell you that you'll need a crapload of extra shims when you update the pulley halves. I learned that the hard way, and still haven't gotten around to installing my pulley halves since I need more shims.

If your belts are too tight and hot, I wouldn't dare run that car! You'll regret it.

IXLR8

Not to worry, I only ran it two or three miles. I checked the alternator bearings when I had the belt off and they felt fine so the heat build-up in the alternator pulley wasn't coming from those.

I'm about to order a few shims.