Dr-Nab
MB Enthusiast
Well... yes is the simple answer to that.. but I don't agree with stop/start on turbo charged cars (petrol or diesel) because shutting the engine off after a hard drive isn't going to do the turbo any favours at all.
tali
MB Enthusiast
Trouble is 100% of diesels are ... Turbo -so stop start would be a no no on all of them it seems.
Pringles
Active Member
I think it saves a bit of fuel but my understanding is that it is mainly in use to reduce emissions. More to go wrong down the line perhaps....
stevieb15
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I read somewhere that if you're stopped for more than 18 seconds financially it's worth switching off, any less is a wot
NISFAN
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Technically speaking.....battery energy is used up to start the engine.....that energy needs to be replaced in the form of extra effort from the alternator, which in turn comes from extra fuel usage.
Therefore, provided the engine is switched off long enough, the amount of fuel it saves not idling will be greater than the energy required to top the battery back up.
Every car will have a different time for it to reach the break even point. That point will even vary depending on ambiant conditions (batteries take longer to charge when cold)
BMW take the whole thing further in that they have a bigger battery installed, and use the breaking event to switch the alternator into boost charge mode. Kind of 'free charge', which makes it more effective than most others.
Some smart petrol engines sense which cylinder is about to fire, and prematurely fire that cylinder to speed up the start process.
To answer the Turbo stop start issue meantioned earlier....although still an issue on a hard charging petrol engine, is no where near as bad as it was in the 'old days'. Modern turbo's are water cooled and oil cooled as opposed to the oil only cooling years ago. Heat soak is not as much of an issue, which used to coke the oil on the shaft. Oil has also improved to lessen the issue further.
On a diesel, exhaust gas temperatures are much lower than Petrol engines, so no issue at all. In numbers petrol engines can have exhaust temps exceeding 1000degC diesels are more like 600-650degC.
Therefore, provided the engine is switched off long enough, the amount of fuel it saves not idling will be greater than the energy required to top the battery back up.
Every car will have a different time for it to reach the break even point. That point will even vary depending on ambiant conditions (batteries take longer to charge when cold)
BMW take the whole thing further in that they have a bigger battery installed, and use the breaking event to switch the alternator into boost charge mode. Kind of 'free charge', which makes it more effective than most others.
Some smart petrol engines sense which cylinder is about to fire, and prematurely fire that cylinder to speed up the start process.
To answer the Turbo stop start issue meantioned earlier....although still an issue on a hard charging petrol engine, is no where near as bad as it was in the 'old days'. Modern turbo's are water cooled and oil cooled as opposed to the oil only cooling years ago. Heat soak is not as much of an issue, which used to coke the oil on the shaft. Oil has also improved to lessen the issue further.
On a diesel, exhaust gas temperatures are much lower than Petrol engines, so no issue at all. In numbers petrol engines can have exhaust temps exceeding 1000degC diesels are more like 600-650degC.
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st4
Banned
Is there not a wear and tear issue with the engine being switched on and off. I'd disable it if it were my car
jonnyMercUK
Active Member
It's habit for me now to switch it off.
I wonder if the engineers anticipated the fatigue life of the on/off switch in your car?
joecash
Active Member
would mercedes introduce it, if it were to prove problematic? time will tell
scillyisles
Active Member
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I read a detailed report some time ago - they quoted the figure as 6 seconds.
NISFAN
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jonnyMercUK
Active Member
Doubt it very much!
grober
MB Master
Almost certain to reduce the life of the starter motor and dual mass flywheel for starters I would expect.
PenelopePitstop
Active Member
I switch off start/stop - eco button when I start the engine. If I forget, engine dies when I stop to leave the car park which surprises me every time.
I use eco button when I'm stuck in traffic for a long time or waiting at red light and I know waiting time is long at this one.
I use eco button when I'm stuck in traffic for a long time or waiting at red light and I know waiting time is long at this one.
Bellow
Hardcore MB Enthusiast
Most manufacturers use conventional starter for cold start then once warm, the combined alternator/starter via a belt.
Except for smart on the MHD 451 where it's all done by the alternator/starter - which has a tendency to misalign the pulleys and shed the belt. Which is unfortunate as said belt is also the water pump drive.
If you count smart as an MB venture - your answer is above.
I would like to see something from MB to state that components have been uprated to compensate for additional startups. Also that NO damage will be caused to the turbo on a sharp shut-off after some hard driving. Consequentially, I assume now that with the ECO button cars there is no longer any need whatsoever to idle the turbo before switching off in any circumstances?
I do the same and wish you could change the default setting to 'off' rather than 'on'.
NISFAN
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I'm sure you will find that the alternator and battery have been upgraded on ECO SS cars. They do also seem to fire up quicker, so would imagine they have as Bellow has said, and alternator/starter, or a beefed up starter. The car has been designed for it.
Can you refer me to the section of the owners manual that even mentions Turbo cool down? ........Nope........because there isn't one.
Now if Mercedes didn't specifically mention it, surely that means that it is NOT necessary? after all they do have a section talking about cooling down the brakes if driven hard.
In any case, if you would prefer to cool the engine and turbo down by idling like they used to in 1985, by all means go ahead and turn off ECO mode. Everbody happy
Lol, at getting a statement that something won't ever get damaged. The manual talks about starting and driving the car....I'm pretty sure MB won't give me a written statement to say that running the engine and driving the car WON'T damage it.
