AO Platinum Member
Join Date: Aug 2003
Location: London, England
no that's not normal!
It sounds like the piston rings may have gone.
Combustion pressure would blow past the piston rings and increase the crankcase pressure, causing the symptoms you see when you remove the oil cap.
Does the gas coming from the oil cap smell like exhaust?
(Don't smell it for too long though eek! )
You need to ask a garage to test do a compression test on each cylinder.
Sorry I don't know what the compression pressure should be, but if one cylinder is very different from the others that is a bad sign...
Oil will also be passing from the crankcase to the combustion chamber, this combined with poor compression will cause poor exhaust emissions.
Audi TT 3.2v6 DSG
xAlfa 156 Selespeed sp3 + Brembo conversion
Fiat Cinquecento 899cc