Is there any way of seeing how much heat has been building up in my engine? Otherwise what is a good indication of when to stop the engine so it will not explode?
A pretty good indicator is the color of your engine. It starts out blue and cold, and then progresses through green and yellow to red. Once it goes red, it is a pretty good idea to shut it down so it doesn't explode. If you want to be completely safe, turn it off in the yellow stage, although it can be a bit time-consuming to keep watch and letting it cool down more often.
Although this is a good answer but i'm looking for something more practical. Something like "If you let it run idle for 300 second it will go KABLAAAM"– MadmenyoDec 23, 2013 at 8:45
2@MennoGouw it also depends on how much energy gets drained, if the internal energy doesn't get drained then it heats up more quickly. you can use a gate to monitor the engine and turn it off Dec 23, 2013 at 8:52