Anchorman and others -
As always, a search can be done on 968.net for the whole thread, but long story short (and you know it won't be) <img src="/forum/images/smilies/968/wink.gif" class="smilie" alt="" /> ...
I was doing my first oil change at home after putting 3K miles on my new-to-me baby and found 7 gear teeth on my magnetic drain plug. Mind you, the car is my daily drive and I had been driving it that way for who knows how long - very much in danger of grenading the motor. Were it not for the coincidence of a timely oil change, I'd have never known. Yes, I had a PPI with all checking out great, and there were lots of records that came with the car, except I didn't know to ask to inspect the tensioner pad and the mechanic (3rd party in another town) didn't utter a peep about it.
Anyway, following STRONG suggestion from the 968.net list, I had my own mechanic pull the valve cover for insepction.
Outcome: 4 missing cam teeth on exhaust cam and 5 missing teeth on intake. Fortunately, there were no more than 2 teeth in a row missing, which kept the chain from jumping the sprockets. The remiaing teeth were pretty worn too. Furthermore, the tensioner guide had been worn down 3-4 mm, but didn't break or crack. I was DANG lucky.
From the worn tensioner pad, it was clear it had never been serviced in 145K miles. From the list I learned that chains stretch and sprocket teeth wear from stretched chains, and stretched chains wear even harder on weakening teeth - a viscous circle.
So I did the only thing a prudent owner would do. Not wanting to risk reliability issues, I replaced the cams with new ($730+/- each) and opted for new lifters for the new cams, plus new tensioner pad and new chain. The variocam unit was fine and in excellent shape. At $900 for new, I opted to keep that used part.
Other "while you are in there' stuff included new water pump, timing belt, seals, belt tensioners, etc. even though the belts had been done a year previous.
More while you are in there: drop the oil pan to find the 2 teeth still missing. "Long as you're in there" with the front cross members detached, I had the motor mounts replaced too, along with all new fluids. Total bill was about $4500.
Lesson: ALWAYS check the variocam unit, chain, and tensioner pads during the PPI and replace the pads and chain every 45-50K miles thereafter, assuming all check out well initially. My best guess is that the cam teeth will last forever if you replace the tensioner and chain frequently. But if the teeth are already worn, they will wear out the pad and chain in a hurry. The regular inspections and replacements would run about $300 parts and labor, I guess...well worth the price when you consider the possible outcome of destroying the engine.
Buzz
