With any internal combustion engine, while the engine is running it is generating a fair amount of heat that is mainly collected by the oil & coolant circulating & dissipated thru the various cooling systems, but all the metal bits & the oil & coolant & everything will get quite hot..... albeit usually only to a controlled level dictated by how effective the cooling systems are & what temp the thermostat opens at etc. Shut the engine down & the oil & coolant cooling systems are no longer running either, & the engine is not getting rid of all that heat into the atmosphere, so it 'soaks' the immediate area & surrounding components, especially if contained under a bonnet or as in this case, the tupperware. If you turn your engine off but leave the ignition on so you can still watch the gauges on one of these hot days you are experiencing atm, or if you want, use another thermometer to watch the temps - you'll likely notice that immediately after shutting down, the temperature of the gauge can actually rise & stay high for maybe as long as 5 mins after shut down before beginning to cool off..... that's Heat Soak, or at least the heat soak we are concerned about here! :thumbup:
So if you only shut your engine down for a short period on a hot day, there's a good chance that if you re-start again within just a few minutes of the last shut-down, things will be somewhat hotter in the engine than they were & that can set all the high temp alarms off; but once the cooling systems are running again, circulating oil & coolant around everything & pumping that thru the various radiators & heat dissipation devices so that it can radiate it into the now moving air, the temperature of everything will come down very quickly & you can ride on happily. :yes:
Edit: if the pavement is already hot from the sun, the added high temps from the engine radiating out can be reflected back into the engine etc, further compounding the heat soak issue. If it's a really hot day & your engine's cooling systems are at or near capacity anyway, simply shutting the engine down can sometimes cause the coolant to boil!! That's one reason that some drivers won't switch off as soon as they pull up, especially if they are driving a diesel engined truck that's been working hard (diesels generally run a little hotter than gas engines) or a turbo-ed vehicle that's been running hard for a while - and it's why many owners here in Aust fit 'turbo-timers' to allow a wind-down/cool off period on stopping, especially for their turbo diesel engined vehicles! The heat soak on & immediately after shut down can actually damage things if it does push the temps up past boiling point!!
This shouldn't be an issue on our Spyders if their cooling systems are otherwise working well, and it's not such a biggie on vehicles that
are not running close to their cooling system's capacity all the time either, but it's still something to be aware of & keep in mind on really hot days if you are working your engine hard &/or close to capacity for a long time! If your temp is up high anyway, then slow down & fast idle for a while to let it cool down a bit before switching off, and don't be surprised if the high temp alarms scream at you if you start up again within just a few minutes - if you do, watch for the temp to come down fairly quickly once you start moving again, & remember, you probably only need to worry if they don't!
