2.0 TDI A4 - Smoke/steam from exhaust | Technical matters | Back Room Forum

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Wed 3 Aug 2016 00:33

2.0 TDI A4 - Smoke/steam from exhaust - Roy Brown

Hi, bought an a4 2.0 tdi b7 a few weeks back

I had went on holidays and the car had sat in my garage

Today when I started the car, i noticed that there was a clear/smoke steam from the exhaust after sitting on idle for a while. I then revved it and it spat water out of one of the tail pipes (no smoke/steam from the other)

Could this possibly be due to it sitting for a while and just needs a good drive to clear it? or does it sound like the start of a DPF regen (already has had a new DPF and egr fitted within 12k miles)

Any help welcomed, thanks

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Wed 3 Aug 2016 09:21

2.0 TDI A4 - Smoke/steam from exhaust - RobJP

Could just be condensation in the exhaust.

Basically, when you burn petrol or diesel, the 2 main end products are carbon dioxide and water (as steam). If the exhaust system isn't up to temperature, some of the steam comes into contact with the cold metal exhaust, and turns into liquid water - think of a hot kettle next to a cold window. As the exhaust system warms up over a few miles, that water gets boiled off again, and expelled into the atmosphere.

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Wed 3 Aug 2016 09:46

2.0 TDI A4 - Smoke/steam from exhaust - Fernando P

Hmmm! Hot water "smoke" can generally only be seen from a diesel engine exhaust in very cold winter weather, when the exhaust metal is suitably cold. Does the engine start up and run smoothly?

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Wed 3 Aug 2016 10:20

2.0 TDI A4 - Smoke/steam from exhaust - edlithgow

Considering worst case scenarios, head gasket?

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