timing belts

[Indi9xx]

Well neither of our 924S's have them-but our original 924 Lux had one to cover the Hall effect sensor & shield it from ill effects.
As all the distributor does on a 924S/944/968 is distribute the spark to each plug in firing order,I would image the benefit of such a shield is not measureable.

The original question that spawned the explanation was what outside influences degrade the belts. Ozone created within the distributor cap is far more corrosive than oxygen, which is far more corrosive than the air around us, especially for rubber components.

Spark performance will indeed not change if the car has or has no ionisation/ozone cap.

 

[blade7]

There's a port on the belt cover on the right that's not connected to anything on my car , what's that for ?

 

[robwright]

That was originally to connect to the air box. As Jon has implied this was deleted by Porsche after discovering it had been the source of some hydraulic locks during heavy rain or driving through water.

 

[Waylander]

That dust cover is not listed as a part for the 968, it was never fitted to them

obviosly not needed or another cost saver

 

[Indi9xx]

968, 944S and 944S2 have a large flange on the bottom/back of the rotor arm to close up the gap between the arm and the diameter of the hole as well as quite close tolerances between the tin plate behind it which is also used as the missing tooth for the hall sensor.

Does not need to be air tight, just to stop it being open to the belt cover, or at least have more square mm of ventilation in the cover than it has between the cover and the distributor cap, if that makes sense.

 

[Indi9xx]

It's potentially not even a problem with the average annual mileage of a typical UK 944 multiplied by four or five years (or hours of exposure to a belt between belt changes) but none the less, a contributing factor that needs to be taken into account of what degrades a belt over time.

You could all decide that as your cars do not cover many miles per year that you could stretch out belt changes to 10 years, ditch the ionisation cap and all sorts of things like that, but that's cutting corners I would not want to cut.

 

[vitesse]

Well I'm not interested in cutting corners-even though both our cars are over 30 yrs old,I have always tried to maintain them as original spec,even to replacing the little rubber bung in the camshaft belt cover where it was missing or nicked after being at a garage.
I'm well aware of the ozone problem with belts but why would Porsche miss it off on our grey car where we are only the 2nd owners & can't see why it would have gone missing at 26K miles having been serviced by a main dealer,the original supplier.
As ozone is present everywhere,there is a continual air change in the engine compartment /distributor cap-differential pressures everywhere,it's effect can only be marginal for the average owner,who listens to forum posts & abides by the advice.

 

[PSH]

Thanks for the info on the 'ionization cap' Jon, I wasn't aware of this ..Mine snapped in half just recently, not bad for 30+ years I guess....I'll add it to my list of 'to get' items now...

cheers

Pete