n1gels

I finally tracked down the source of annoying engine rattle on my 997.2. The torx screw that secures the water pipe to the thermostat housing was loose and the pear shaped plate it secures was free to rattle on the pipe. See the left image.

While tightening this screw I noticed a threaded screw hole that looked suspiciously clean, as if a screw had fallen out. See the "?" arrow in the second image. I checked the Porsche parts catalog and can't identify it. Is something missing? My best guess is that this might have held a clamp for the water pipe, but there are no telltale marks on the pipe where one might have been. So, perhaps this is supposed to be unused, but I figured I'd ask.

Finally, while in the parts catalog I noticed that this washer appears to be a threaded plug with a pear shaped flange, rather than a plug and a separate washer. Oddly, this part is not numbered in the catalog. I've circled the part in the catalog image below. Now I'm curious whether this is supposed to be a single part and the one on my car is broken. I'm also puzzled as to why my car didn't dump its coolant when the screw and pear shaped plate was rattling loose. Plain dumb luck?

Thoughts?

Fred R. C4S

Plain dumb luck?

Bingo! It appears from the exploded view that this pipe is pushed into the hole, against an o-ring and held secure by the pear shaped plate and screw. Not the best method, but considering the space in which the designer had to work it is effective. You're lucky that there is not a lot of room in the area for the pipe to back out. I also wonder what the apparent ridges on the end of the pipe represent. They may be what initially keeps the pipe in the hole with plate and screw as a more security.

n1gels

I wondered if they're screw threads, but it makes more sense that this is part of the pipe (hence no separate part number), and that the plate just holds it in. When I tightened the screw, there was no indication that the o-ring was being compressed. I'm assuming that the pipe is a tight fit and the o-ring is stuck to the pipe and the hole and would require some force to remove it. That's what kept it from dumping coolant and converting my 997 into an air-cooled model