Posted by casebro on Monday, August 18, 2003 at 5:11PM :
In Reply to: What causes a "heat sink" type of condition? posted by Chris Lube Lublin on Monday, August 18, 2003 at 2:25AM :
The cylinder walls and head have a blast furnace burning inside. It takes time for the heat to soak out through the cast iron, which is normally OK since the cooling system is removing the heat as it soaks out. When you shut down your cooling system, the heat will contiue to soak through the block, but the coolant isn't being pumped through, so the coolant gets hotter than usual. If you leave it shut down, convection current (better in the old vertical tube radiators- cooler coolant sinks, drawing hot coolant out of engine) would cool the block pretty soon. If you restart too soon, the coolant has picked up the heat from the block but not had the time to bring heat to the radiator. Newer cross-flow radiators are a trade off- less convection cooling but they suffer less loss of cooling area as the coolant drops due to leakage.