Cool down?

[B.K.]

I'm going through the manual and somewhere it says one should cool the car down after hard driving before making a stop and shuting it off. I understand this is necessary for turbo charged cars, but why the heck this one needs a cool down?

[willyjp]

I'm going through the manual and somewhere it says one should cool the car down after hard driving before making a stop and shuting it off. I understand this is necessary for turbo charged cars, but why the heck this one needs a cool down?

always a good idea if you've been running HARD

if you've just been going with the traffic, probably doesn't matter

everything that gets real hot benefits from a slower cool down than an abrupt one...less sudden expansion/contraction stress on all the joints between parts; more time for the oil and water cooling systems to catch up with the heat load and begin to drain it off....etc., etc..

check some of the threads on brakes and rotor warping...at track training events they typically warn you NOT to set your emergency brake when you come into the pits with hot discs, to avoid warping the rear rotors...same goes for holding the brakes on once you stop

the thing about turbo chargers came, especially, from non-water cooled turbos; my '84 Maserati 2.5 bi-turbo was a good example: after hard running (where the turbo was spun up most of the time), the only source of cooling was the oil circulation and if you shut the engine down, you stopped that!

conventional oils were very susceptible to "coking" (carbonizing) in the turbo bearings under those conditions, shortening the turbo's life

water cooling of turbos and synthetic oils have done a lot toward mitigating that particular problem, but gradual cool down is still a good idea....for cars OR horses!....after a hard run.

[HovyR8]

I dont think its only for turbochargerd cars. Any car driven hard needs to cool off by having the engine run for 5-10 minutes. I was told driving the car at low speed instead of just running the engine while steady is even better.