Tapping, rattling, clicking...?

All, Here's an issue I've noticed a few times: If I leave the car sitting for a while (two weeks or more), I hear a kind of tapping or clicking sound coming from the engine area. It rises and falls with revs. Sounds like it could be in the area of the water pump. This sound goes away after about 5 minutes, not to return until the next time I leave the car for too long. By way of background, the car is a 2004 C2 with about 37,000 miles. I will have to wait a while to get a video of the sound, because I'm going to be using the car pretty often for the next month or so. But until then, does this, uh, sound, sound familiar to anyone? Thanks

Leaky lifter?

could be a pulley bearing ... or any number of other issues... what oil are you using, how often is it changed, what filter, any water consumption, frequency of ticks...(one/sec, 10/sec) - stock exhaust? cats every been replaced - you know...the variables

Perfectly normal with the 996 MKI but not sure about the the MKII. This happens to my MY99 996 when it sits for a week or more. Noisy hydraulic lifters caused by oil draining into sump when the car has not been driven for a while. Do a search on Renntech as this has been discussed in length.

Thanks for the replies. Oil - Mobil 1 0W40, changed it about a month ago. Have heard this noise both before and after the change. Used Porsche filter. Old filter had no metal at all in it. Timing of noise is probably 3/second, increasing linearly with revs. Exhaust is Fabspeed, just the cans. Cats are stock. The car has run very well, no CELs, was fast at NJMP last weekend, no problems w engine response, no other issues. I will check out the RennTech forums to see if I can find a similar situation. Thanks guys.

the ticking does happen when lifters over time "de-flate" but 5 minutes seems a little long for a lifter IMO removing the belt takes like 20 seconds...try removing it and seeing if the ticking is still there next time it sits. that will eliminate all the belt driven devices

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If the noise is from the engine simply sitting unused for a couple of weeks, the Porsche techs I consult with tell me that to reduce the amount of noise at cold engine start after the car has sat a while since the engine last run Swepco 502 Oil Improver is recommended. I had some analyzed and it contains 200ppm moly. I'm not an oil additive fan, but I decided to try this just to see if there was any difference. I have used this additive in both of my cars and can't tell the difference, but my Porsches do not sit very long between uses and the engines are pretty quiet from start. Sincerely, Macster.

great solution here, ditch the second car and drive your Porsche more often, it's a car, it was made to be driven, not worshiped in the garage.

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I totally agree with that. This actually is my only car, and I've put 20,000 miles on it in the two years I've had it, including about 1,200 track miles. It unfortunately doesn't even get worshiped in a garage, more like put up on a lift and surrounded by minivans and BMWs sedans (and a couple 993s - one reason I thought the garage was OK). Problem is, living in Manhattan, driving is pretty much a weekend-only activity. And in the summer it's typical for me to be away for one or two weekends in a row. I'm taking the car in tomorrow for DE inspection. I will ask about lifter issues and the additives suggested by Macster. I won't be able to replicate the issue, but for $189/hour, hopefully they will have some thoughts. Thanks to all.