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Matt
Matt, Mechanical Engineer
Category: Audi
Satisfied Customers: 21994
Experience:  BEng hons Mech engineering, in auto industry 22 years
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Ive got a 2007 audi a4 170 tdi s line when starting the car

Customer Question

I've got a 2007 audi a4 170 tdi s line when starting the car cold and leaving it for about 5 minutes get blue smoke from the exhaust but when normal it clears the engine is all so a bit lumpy to until Norma temperature there are no fult codes or loosing power or using oil or coolant and sometimes get a strong diesel smell to please help my name is XXXXX XXXXX has 75000 miles on it and grits serviced every year
Submitted: 3 years ago.
Category: Audi
Expert:  Matt replied 3 years ago.
Hello


The first thing I'd check is the crankcase pressure relief valve (PCV) these are sprung loaded and are only meant to 'burp' excess pressure every now and then. The exiting gas is piped back to the inlet , however should the valve stick open then the engine tends to suck the air out of the crankcase all the time and this carrys oil over with it.

If you remove the air intake pipe and look inside where the crankcase breather is plumbed in you may find evidence of oil.

If you do find oil replace the valve. If this is all OK then its possible that the valve stem seals are past their best and are drip-feeding oil into the intake. These can be replaced without removing the head by a competent garage in half a day or so

Also check inside the intake just after the turbo for any signs of oil as this would be an indication that the turbo oil seal is starting to fail and a replacement / rebuilt turbo may well be required. Have a feel of the turbine wheel - there should be no play radially at all - but a little bit of axial / end to end float is normal