We have a 16 yr Merc 312 and I wonder what the optimum time is for turning off the engine - is it better to leave it running while stationary for x mins or turn it off? What is the shortest time it is worth turning the engine off for?
above advice is correct....let the turbo spin down and cool before switching off. probably about 2 minutes. then switch off if its going to be another 5 minutes. all depends on the health of the starter and charging systems though. no 2 older vehicles are the same
Putting aside turbo issues those on mpg economy competitions will turn off the engine after as little as 30 seconds - but this is with petrol engines and the optimum could be a bit longer for diesels. However, in a queue, think of those stationary near you and turn it off!
No turbo. The system seems fine. Diesel engine which regularly gets treated but can be a bit smokey so I tend to turn it off but wondered whether I would generate more emissions by turning it on and off regularly or leaving it on.