Is it safe to assume that I could diagnose white mist-like smoke coming out of exhaust by testing coolant system for traces of exhaust gases (using available kits).

If so, is the expansion tank a good place to try? My reasoning to doubt that being that the expansion/coolant tank may not be a direct part of the coolant circulation.

Ideally the test should be done on the radiator cap... of course there's no such opening.

Is there another service port where I could try that?

(I should mention that like most of you I feel comfortable doing repairs myself, having done jobs from chassis, to electrical problems, to cracked cylinder head)

 

In theory you could use a 5 gas analyzer and sniff for HC's (hydro carbons) at the coolant expansion tank. I have never done this on the cayenne so I can't say if it works or not. I would pull the plugs, inspect them very closely for signs of coolant. Do a leak down test, bubbles in the cooling system equals faulty head gasket, head, etc. Bore scope might shine some light on things too.

 

you mean the 3-5K toolkit revelaed when searching froogle.com. I'm afraid that's pricier than the cylinder head


I did buy a $45 kit from Napa (I'm in the States)

which works like this:


But I am afraid the expansion tank is not a direct part of the circulation (according to instruction the kit should go into the radiator cap opening... if the car has one. I did not find any other service port that I may use.

P.S. I did test the kit by "sniffing" some gas directly from the exhaust pipes in the back and the liquid turned nice yellow, so it was working...

Thank you for your help. Taking the car to another "reputable" dealer tomorrow. Wish me luck.