I have heard a lot of hot engins cooling down, did you know even sheds make the same noise when they are cooling down from the hot sun in the outback, this noise is created because the atoms are losing there heat energy and inturn vibrate less, meaning they need less room. therefore the metal shrinks... It is quite a different noise than an motor that is still trying to run.
please don't ? my intelegence and obsevation skills.
I believe Jamie responce was a fair one due to the lack of information, however if you had read my second post carfully, YOU would know why Nick has resopnded with the correct info...