"Daz N" <darren.nicholl(AT)zen.co.uk> wrote in message
...
> Hi,
>
> The other day my wife drove my car and I drove hers, she decided to show
me
> how fast mine is by leaving me behind while pulling onto the motorway.
When
> she changed gear I was surprised at how much water came out of both
exhaust
> pipes.
>
> Any ideas why this happens?

One of the main gasoline combustion products is water which due to the
combustion temperature will be in the vapor phase as the combustion products
exit the engine through the exhaust valves. When you first start a car, the
exhaust system components will be cold and the water vapor will condense
out.in them - mostly towards the rear of the car. If you drive sedately
while the car warms up, this liquid water will gradually heat up with the
exhaust components and be revaporized and blend with the exhaust. What
likely happened is there was insufficient time for the water to be
re-vaporized before your wife put her foot down. The added rush of new
exhaust blew the still liquid water out the tailpipes and that's what you
likely saw.

I assume it was water, would it indicate a
> problem?

In the absence of smoke of some sort accompanying the water, it is unlikely
problematic. A similar thing happens in cold weather when the warm moisture
laden exhaust contacts the cold air outside the exhaust and the water
condenses to "steam".

> I hadn't just been through the car wash or anything and the road's have
been
> dry for several days, the car has also done about 5-6 miles before this
> happened so the engine was warm.
>
> Thanks in advance
>
> Daz
>
>