I use an electric powered pressure washer, on a lowish spray setting.
Don't spray directly at dizzy or the black boxes. And not on hot engine.

It gets the dust off at least. The purple stuff works great but
don''t let it sit on the aluminium too long, when you find a good trap.

the controversial simple green works less well, after removing dust
and engine still wet.

alistair

On 24-Jun-10, at 7:14 PM, Mike Rocket J Squirrel wrote:

After doing a lot of dusty dirt roads, my van's engine is looking
decidedly furry on top. It's effectively dirt-colored now.

Can you just hose the thing off with some purple power cleaner? I don't
want to use anything that can't go down the storm drain.

I don't know if Bend (Oregon, USA, Earth) has any carwashes with proper
traps for cleaning engines.

--
Mike "Rocket J Squirrel" Elliott
84 Westfalia: Mellow Yellow ("The Electrical Banana")
74 Westrailia: (Ladybug Trailer company, San Juan Capistrano, Calif.)
Bend, OR
KG6RCR