I was out in the bush today with my fj40 and just as i finished climbing and then descending a big hill my friend looked back and noticed a huge cloud of white smoke coming out of the tailpipe. i shut it off but couldn't identify any problems so i drove home and noticed the smoke was much less as soon as i started back home. does anyone have any ideas what could have caused this? oh yeah just after that the gasket between the exhaust manifold and the first pipe started leaking a little bite. thanks for the help