I will look at that too, thanks. The front is looking fine but there might be something I am overlooking. It is full of bugs but it still let's enough air through from that side methinks.
This would be 5 mins or something. Last time was in an open garage when it became pretty hot and that was about 15 mins (was stationary before that for about 5 mins as well) .
The fan just doesn't spin and for the rest it all seems OK (as fair as this leech in cars knows ).
Why? If you mine in tunnels you mine straight which means that the lava would flow towards you. Since the lava does that really slowly you can place blocks to prevent that from happening. That is also why I do not mine up or straight down.