» » »

Audi Q&A

Ask Your Question

2004 Audi A6 Question: White smoke

 

Question

bretsinclair, V6, Floral Park, NY, January 27, 2010, 03:09
 Rookie

Hi, I have 100k on the clock and the car works fabulously. It does however emits rather thick white smoke from the tail pipe almost all the time. Whether it is cold or hot. The cooling liquid does not seem to be dropping fast. I have done almost 250 miles with it without having to refill.
It went through a brand new MOT and has been serviced 4000 miles ago.
Any advice welcome thanks

2 Answers
Flag This
  • Answer #1

    patrick mannion from Greg Solow's Engine Room, January 27, 2010, 19:58
    Profile_thumbnail
     Master

    On first start up of any car in the morning fuel is not being atomized properly and doesn't burn properly until the engine reaches proper operating temperature. An engine that is burning oil emits blue colored smoke that has an odor of burning oil. It is heavy blue to blue gray in color. If the engine has worn valve guides or valve guide seals oil may drip into the cylinders when the engine is turned off and allowed to cool, then when you start the engine up in the morning you get that trail of smoke out the exhaust. light colored smoke out the exhaust is normal until the engine warms up, especially noticeable on cold mornings dense air. White or sweet smelling smoke out the exhaust perhaps accompanied by rough running would be a sign of a blown head gasket. You will notice grayish colored smoke out the exhaust pipe until the engine warms up. If you are loosing coolant and having to top up the coolant level frequently it may indicate signs of a blown head gasket and needs to be investigated to avoid doing serious engine damage.
    The most accurate way to test for a blown head gasket on a gasoline engine is to test for the presence of carbon monoxide in the cooling system. Snap-On, Matco (part # CO 2000), and Napa sell a tool to check to carry out this test. Another link to a supplier of this tool is http://www.etoolcart.com/combustion-leak-detector-lis75500.aspx. Carbon Monoxide is only present if there is a blown head gasket or cracked cylinder head. http://www.arrowheadradiator.com/head_gasket_or_combustion_leak_test.htm I think the napa part number 700-1006. http://www.blockchek.com/instructions.htm . Signs of a blown head gasket are coolant loss (frequently have to top up the coolant level of the engine without seeing an obvious leak), experiencing over heating or rough engine running or the presence of white sweet smelling steam from the exhaust. A badly blown head gasket may allow engine coolant and oil to mix.

    Flag This
  • Reply

    bretsinclair, January 27, 2010, 23:50
     Rookie

    Hello again, yesterday night I drove the car for 1 hour coming back from work. I observed the following:

    The cooling liquid level still has not moved.
    The car does not seem to emit fumes/smoke while being driven, it is mostly when it is idle at the light with or without a gear in.
    If I put my glasses over the exhaust it steams them quickly so it looks like it could be vapour.
    The smoke has no specific odour.
    The fumes come from either side of the pipes (there are 2) and sometimes both.
    The temperature level when hot is set to 90 deg Celsius and never moves.
    There is full power and I am not sensing any loss of compression.

    Isn't that something that would be seen on an MOT if it was the head gasket?

    The car works fabulously, I have done almost 300 miles with it and have never refilled the coolant and the coolant sensor isn't flashing.

    I bought it 2 weeks ago with full Audi service history. It went through a brand new MOT with nothing at all and has been serviced 4000 miles ago. Next service is due in 14000 miles.

    The only thing I had to to is fill up the oil with 1 litre as the oil warning went on. Other than that, no loss of compression, no loss of power, it sounds and drives perfectly.

    I noticed the smoke sometimes stops coming out and then comes back so there obviously is something weird. But it is thick white smoke and not blue or dark smoke.

    Thanks and regards

    Flag This
  • Reply

    patrick mannion, January 28, 2010, 20:19
    Profile_thumbnail
     Master

    No loss of coolant, and no overheating issues are a good sign. Perhaps carry out the mentioned chemical "block check" to put your mind more at ease about the head gasket being sound.

    Reply
    Flag This
  • Medium-star Best Answer
    January 30, 2010, 18:08
     Journeyman

    if your glasses dried clean and not streaky, oily or slick then it may just be water vapor. try using a white paper towel over the tail pipe to catch and filter the exhaust. if it dries completely without color its water. any colors or slickness can help determine what it is.

    Reply
    Flag This