It’s the scene every 996 owner fears most. You start the car, there’s a puff of smoke followed by the death rattle and it’s game over. Time for a new engine. (Or more likely, a new car as engine and car are about the same price these days.)
The interesting thing here was that there was no rattle, just smoke. I had been at Summit Point the previous day and had a huge smoke cloud come out after turn 10. Coolant was a bit low which was worrying, but the smoke was just there at startup which usually indicates a bad Air Oil Separator (AOS), which is a common failure on these cars.
We sent an oil sample off to the lab just to be safe and had the car towed to TPCRacing in Jessup. They did a great job sorting it out and getting me back on the road again. It turns out I had two unrelated problems: leaking water pump and bad AOS. I had planned to have the AOS changed whenever the next time I got a new clutch and I suspected it was about time for the water pump, but probably should have had it done already. So I dodged a bullet.
The water pump (996-106-011-57-M100) was leaking at the housing and through the pulley seal. You can see from the photo below that the play in the bearing had allowed the blades to touch and score the block just a bit.
Many people make the mistake of using a pump with metal blades thinking it would be an upgrade. The problem is that when they contact the block, the debris can be catastrophic. The plastic impeller fails more gracefully.
Early expansion tanks have a tendency to fail on track cars, so we got the updated tank while everything was apart (996-106-147-56-OEM). Shop around. Genuine Porsche tanks can run as much as $600, but you should be able to find them for around half of that (which is still nuts…) if you shop around a bit. In this case, the hoses were also brittle and failing (996-106-850-05-M100).
The Air Oil Separator is supposed to separate oil vapor from the crank case and return it to the intake path. This appears to be an original item. They have gone through a couple of revisions since (996-107-023-55-M100). When they start to fail, you get about a tablespoon of oil that pools in your cylinders causing smoke at start up (see video.) When the fail completely, you can hydrolock the engine. Given where it sits on the engine, it’s impossible to inspect visually. You should think of it as a wear item and replace it whenever you get a clutch (like the IMS bearing.)
We rounded out the repairs with a new idler pulley and belt. The idler pulley felt OK when it was on the car, but fell to pieces when we took it off.