"seeray" wrote in message ...
: Hey all a buddy has a Mercruiser 140hp IO, it has a cracked intake manifold
: and is leaking water out the side. He thought that he could run it like that
: for the summer and just replace it this fall. Well the problem is, is that
: it wont idle. It runs fine above 1500 rpm. Below that it just dies.

The crack lets air in, which leans out the mixture. Running it as lean
as he is considering the symptoms you write of, will hole a piston
and burn exhaust valves in very short order.

Dave