Blue smoke on trackdays

[victortun]

My high mileage (100K miles) facelift 996 C2 2001 blows out sudden surge of blue smoke when accelerating after a longish bend when track driving (enough to be black flagged and others to ask re health of engine). This only happens if the oil level is above a quarter and does keep happening til the level drops during the day. Engine also smokes on starting after sitting in pits for a while.
Local Porsche specialist said this is a known problem with pre-facelift models and for them changing to a modified oil separater stops oil going into the breather hose. Post facelift models have the modified separater.
We tried changing it in my car and not surprisingly found it had the new design separater and it wasn't possible to see if the old one was faulty in any way.
I'll see what happens at the next track day (if I'm brave enough to fill the oil to the top) but any ideas?

 

[hothatch2002]

I used to race modified saloon cars, and oil surge is a common problem with cars when driven hard on a track. High mileage cars will have more engine wear than ones with less miles (this is obvious), but some people have a knee-jerk reaction to this statement and assume their engines are knackered - not true!! The amount of wear is very small when measured (thousands of an inch) but it makes a difference none the less. Most common reason for oil surge is when the piston rings are worn and causes crankcase compression at high revs, which in turn causes oil to enter the breather pipe which is connected to the inlet hose on the throttle housing. The resultant smoke is the burning off of the oil entering the engine via the breather, not a huge problem from a mechanical point of view. What most people do on race cars is to disconnect this breather pipe from the throttle hose and connect it to a small plastic bottle to act as an oil surge catch tank. This will stop the smoke, and hence the black flag. Be careful to keep an eye on your oil level and pressure. My advice is to keep the oil topped up in the sump and let it surge into the catch tank, then refill after your session. Find somewhere in the engine bay to cable-tie the bottle in place, then secure the pipe into this - remember to put some small holes in the top of this bottle to allow the air out during surge or it will just blow the pipe out and spray the oil all over your engine bay - nice!! You will also need the blank off the hole left in the throttle hose where the breather pipe used to go. As for the condition of your engine - I wouldn't worry too much, it is probably fine. You must remember that when the oil gets really hot ( track day hot), it will become very thin and tends to find its way to all sorts of places. Good luck.

 

[carrera4boy]

Happens in my pre-face lift 996 occasionally, mainly when i'm burning round the Ring or at Asda getting the shopping[8|]. Nothing to worry about. Thanks Hot Hatch for your expert analysis, very appreciated.[]
Si

 

[victortun]

Thanks Hothatch, for a very reassuring and knowledgable reply. I thought I may have been looking at reconditioning the engine (or selling the car [] ). As it's not really a race car I won't rush into fitting the catch tank but I'll save your post for future reference. As carrera4boy said, very much appreciated.
Victor