on my broz, the heating had stopped working an hour or two before whilst he was on his way home. He was home for about an hour and a half then went back out, Checked the plugs leads for any water going in, was dry. then we set of to go have some 'fun' and he'd parked up 5mins later saying his temperature had shot up. found his rad was pissing out the front. luckily had a spare. got that in and now its running fine.