nassim ... 3/2/2013
2002 Audi TT Quattro Base 4 Cyl 1.8L
Is oil in intercoolers strict proof of turbo failure?
The breather system should be checked by removing the oil dipstick and use a vacuum gauge on the dipstick tube to measure engine vacuum in the crankcase. The needle should barely fluctuate plus/minus 1" of vacuum at idle. Should there be more vacuum than this or if the needle does not move and reads "0", then inspect the breather system for a blocked suction jet valve or bad check valve/breather. If that checks out normal then yes I would agree that the turbo is junk and that all your power loss might be also related to a now partially restricted catalytic converter that has been taking on oil from the bad turbo. Do the vacuum test next. If the turbo is replaced, make sure to completely drain and clean the oil from the intercooler. The turbo oil cooler lines should always be replaced when installing a new turbo.