Reuben

Today, the third belt in a month snapped and I just managed to cruise home. I have added two shims and checked the tension with a 'Kriket' gauge. Short of adding more shims to be on the safe side, any advice? I even compared the tension (by hand) with a friend's 993, and my v-belt felt just fine. I noticed a bit of fraying, and should probably have changed the belt then and there. What could cause a new belt to fray within a week?

Many thanks in advance for your input.

guards red

I'd check the running face of both pulleys. The outer one is subject to an update so I'd check you have the latest halves too. Porsche charge silly money for the update, might be worth considering the RS pulley instead which works out a little more but you only need one belt with it.

Check also that you are rotating the engine as you progressively tighten the allen screws for the inner pulley and the large nut for the outer one. The pulleys should have little or no run out with the engine running meaning they should not look like there's any wobble when you look at them sidewards on.

Lastly, and perhaps firstly, check that the fan housing is sitting in the right grooves on the crankcase ensuring the belts and pulleys are lined up.

Best of luck
GR

black ice

It doesn't look like it could, but if the little wheel bearing on your belt sensor is worn it can damage your belts. What kind of tension are you getting on the Krikit? Which belt is failing?

dave

Reuben

Thanks, GR and Dave. The belt tension sensor was replaced not long ago.

GR: How does one rotate the engine when tightening the allen screws? By turning over the engine with the ignition key, but without starting it?

Akerlie

Whatever you do do not do that, the allen key will come flying !!!

There should be room to fasten the bolts with the allen key and holding/turning the fan with your hand.

Edit: ok, misunderstood you slightly you should be able to turn the fan by hand so you can reach the three bolts with your allen key, otherwise you could turn the fan by using a key on the hex not on the end of the shaft

Mike J

Do you have any picts so we can see the nature of the failure, i.e. snapped, worn through? Perhaps its too loose and you heated up the belt from slippage? Too tight? Are you fan bearings good so its easy to rotate, or is the belt working really hard?

Cheers,

Mike

guards red

I turn the engine by hand, 17mm (from memory!) cranked ring spanner on the crankshaft end bolt. I find it's the only way to ensure the pulley halves are seated squarely and correctly. I tighten the allen screws progressively then rotate the crank till the next screw is on top and repeat till it's seated and the screws are torqued. I repeat with the fan bolt rotating the engine a bit at a time. Make sure you only rotate clockwise. Done this many times with no problems.

C4SJOHN

Only use fan belts that have Porsche on them, after market belts don't work as well in the grove as well and brake up.....

Mike J

Yes, using Porsche brand belts is a good recommendation, often we get weird side effects using the alternative brands.

I also crank the engine over to make sure the belt is in the "groove" so to speak as I tighten up the bolts, but I pull the DME and crank the engine over...that way I get multiple turnovers to check the tension.

Garth S

To achieve adequate tension to rotate the engine when installing new belts ( as they are flopping around as you start to tighten nuts/bolts) ..... pinch the two long runs of the belt together between the pulleys, and spin the alternator shaft with either a 24mm wrench or 10mm 12-point: this works to get you to the position where the pulley halves close equally on on their shim stack & avoid pinching the belt.

96C4S

porsche has a pulley update.

Reuben

Thanks all, for the good advice. I shall start from scratch, and make sure that the various parts are seated properly before progressing.

And yes, I only use Porsche belts.

AOW162435

+1


Andreas

LuftKuhler

You may also want to check to make sure there is no debris in the engine compartment, for example, piece of the old belt....

Ask me how I know....