I did mine at 120k km. Belt broke as I was taking it out, too.

 

I just had my mechanic replace my belt at 90K. The belt was still in pretty good shape but good peace of mind to take care of it.

 

When you guys' mechanics are replacing yours, are the drilling out & pulling the gear?

 

not sure what the guy did, but I can give you the number to his shop, may be if you call he'd tell you?

 

Thats the only way the belt can be replaced,....

 

My mechanic, who looks amazingly similar to me, yes, is drilling out the pin and pulling the gear. See http://p-car.com/diy/dualbelt/.

 

One thing I'd love to change about the 993 is the ignition system. It's such an antique. The distributor belt is a PITA to replace, the bearings, caps, and rotors are expensive, and the wires cost a fortune and are a HUGE pain to replace. Altogether a crap setup -- high-maintenance, labor intensive, expensive.

Is there any good reason why someone can't make a kit for a modern, coil-on-plug ignition system? No distributor, no caps, rotors, or wires. Nothing to wear. I'd pay good money for something like that. The long-term savings would be immense.

I'm guessing the real problem here is the ECU, which is not designed to control spark, and can't be modified to do so. Sigh.

 

Yep,..thats right,....

Spend a ton of money on good aftermarket Engine Management such as Motec M600 and you can do it.

Unfortunately, it would no longer be smog-legal (OBD-1) or smog compliant (OBD-2).

That "old" distributor was a pretty cost-effective and reliable solution at the time. Current Motronic systems (M7.2 and later) supports C-O-P operation.

Given how long these things last and the annual mileage that most cars accumulate, IMHO its not an unmanagable expense.

 

Yep. Also, keep in mind the coil on plug systems have their own problems - just ask Cayenne, 996 and Audi owners (to name a few).

Cheers,
Joe

 

Somewhat of a hijack, but I agree wholeheartedly. I've had to replace indiv coils on a Nissan and Honda, so far (yeah, modern "reliable" cars!!). And I have replaced exactly one ignition coil and one distributor (points/condenser era on the distrib.) in decades of backyard wrenching for my entire family since I was a kid, extended family as I grew up, and friends throughout all those years. There is something to be said for simple solutions that work ...and reliably so over the years. One dizzy belt every 90K ain't bad in my book.

...and now that I think about it, that one ignition coil I did replace was a mod, and not due to its failure

Edward

 

Should the belt fail on the road, can one not run on the primary distributor to get home?

As for the secondary distributor, I'd pull the rotor and disconnect the leads going to that ignition coil. Would that make sense to do?

 

Hi Alex,

Yessir, in the majority of situations, the operational distributor will get you home without question.

The problem lies with where the lower distributor's rotor comes to rest when the belt breaks. If it stops while lined up with a cylinder's tab inside the cap, it keeps firing that cylinder at all the wrong times resulting in detonation and melted pistons, heads, broken rings, etc. Its truly expensive.

Removing the rotor is the best solution for preventing catastrophic engine damage until one can replace the belt.

 

Great tip, Steve! Hope it never happens, of course, but very good to know as a "just in case" survival point. Thanks!

Edward

 

Great advice Steve,

We really owe you and all the other Porsche techs for advice on these older Porsches!

Bert

 

Hi Steve,

OK, some thoughts. I may have tons of Porsche books, but I am new to these.

Is the hall effect sensor within the distributor and if so, then it would have a 6 pronged rotor. I may be an electronics tech, but I'm not up on hall effect sensors. Wouldn't it only trigger the coil if the rotor sweeps past the hall effect sensor?

And if none of the above is the case, what triggers the coil and where is it triggered from?

Also, a misfire is quite noticeable from experience. I'd pull in the clutch and turn off the ignition ASAP. Very little can happen in the way of melting pistons, etc. in a few seconds. Thats provided belt failure is noticeable.

I'll buy a spare belt and keep it with my DME relay.