Originally Posted by
Blknight.aus
my 2 c on this...
dont idle your engine on startup let it get oil pressure, count to 10 then drive off... shut downs can vary.....
If youve been working the box off of it it will be hot even NA engines will benefit from a 2-3 minute cool down to "normalise" the engines themal loading. the reason is simple, if you shut down a freshly hard worked cast iron engine it has a lot of latent heat in parts of it (piston heads, the sides of the block, con rods manifolds) that dont have access to the "wet" cooling system. When you shut down you stop the coolant circulating and stop the airflow in the engine bay, as the parts of the block pass the stored heat back into the cooling system its possable to have the engine overheat while its shutdown.. The same holds true for an alloy engine but the times are shorter as aluminium is a much better conductor of heat. Turbo engines follow the same rule but also have the turbo to worry about for reasons that IMHO have been perfectly delt with already.
There are a few circumstances when you DO NOT shut down your engine for a prolonged holt. when its COLD... If your above the alpine line and its cold enough (below the minimum intifreze temp of your coolant) you dont shut down the engine for a prolonged halt. If the cooling system freezes you have to defrost it somehow before starting up or you will frell the engine.. In some cases if the battery is not preforming due to the cold and the block and air is cold enough a diesel wont create enough heat from compression to start itself which is why in places like canada cars are fitted with electric engine warmers.