Finding a manifold leak.

[David Boreham <uunet!inmos.com!davidb@EDDIE.MIT.EDU>]

Run the engine (idling). 
Pour a bucket of water over the inlet manifold.
If the engine speed drops or steam comes out of
the tailpipe then you've got a leak.
More accurate pouring will locate the leak position.

(Don't throw so much water over that the exhaust cracks!).