Re water in petrol

[Keith Cook]

Remembering the short discussion some time back about aqueous fluid in petrol
tanks I thought this bit I found on a "Mini" site (Hey - no-one's perfect!)
might be of interest.
"
Water in fuel tank, removal using meths
If you poor water into a running engine, it won't die, unless you get too much
water... If you get water in the fuel system, chances are it won't go into the
engine though. It will sit in the bottom of the tank (petrol floats on water),
in the metal pipe under the car, and depending on your type of carb, maybe in
the bottom of the float chamber (HS carbs will probably suck it up). Now, the
reason water doesn't mix with petrol is that water is polar, and petrol isn't.
Alcohol is a bit of both. If you mix petrol with water and shake, you get
little balls of petrol and water which eventually settle with the water at the
bottom and the petrol firmly on top. If you mix alcohol and water, or alcohol
and petrol, you get a homogeneous mixture, you don't get any seperation of the
fluids. Now, what if you mix some water, quite a lot of meths and petrol? The
alcohol and the water join together (at the molecular level) and such groups
can then mix with the petrol. So you get the water and the alcohol spread
through the petrol, and it all gets drawn through the engine. This isn't good
for the engine but isn't particularly bad for it either. Alcohol is very bad
for aluminium if it is left long enough, and in high enough concentrations. If
you end up with a mayonase type slimy mess in the tank, then you didn't do it
right, and probably need to add more meths, or a commercial dewatering agent.
Even better, dump it and start again."