"Dave Liquorice" wrote in message
idual.net...
On Tue, 24 Jul 2018 00:14:28 +0100, Dave Plowman (News) wrote:

But why would you bother when it's simple to just turn off the ignition?

'cause a diesel, burning it's own oil, will just carry on switched
off or not... B-)

Surely the important thing is to get the car to a standstill as safely
as possible?

So just use the foot brake a bit harder than normal to bring both car
and engine to a safe and controlled standstill.

The orginal start of this thread was based in the US. They mostly
drive automatics over there so the pigging thing will change down to
counter act the braking. Selecting N still doesn't strike me as
"right" though, selecting the highest fixed drive and braking ought
to work. Assuming the auto box and/or computers will allow that
change to happen with the engine under full throttle.

Yes, the whole concept of removing the mechanical load from an engine that
is running out of control seems counter-intuitive, when the object would
seem to be to remove the problem at source by cutting off the fuel which is
best achieved by turning off the ignition. That hinges critically on not
accidentally locking the steering wheel: the thing that the video said was
highly likely but people on this thread have said doesn't happen until the
keys are removed - unless anyone knows of exceptions to that for certain
vehicles.

Braking the engine when it is transmitting power to the wheels will lead to
a "fight" between brakes and engine, with the risk that the energy that the
engine is generating will heat up brakes too much. If you have an engine
generating maybe 100 hp, you've got to dissipate that sort of energy in the
brakes. What is the effect of the discs heating up dramatically: can it
cause loss of braking force? They did mention something about "burning out
the brakes" which was the reason for contemplating using the "emergency
brake" instead, as if that magically used different pads and wouldn't be
affected in exactly the same way by brake heating.