My first question is Diesel related:

Why does a Diesel engine not produce any manifold vacuum and therefore require a vacuum pump, while a gas engine creates its own vacuum?

My next question is Mercedes specific.

What's the logic behind the two settings on the light switch that turn on left or right side signal lights?


Going by past experience in reading posts here, I'll bet that Longston will have the most thorough answer to both of these questions. Thanks.

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Dave
1995 C280
1999 Triumph Daytona 955I - my speed fix.
1982 300TD - Gone, but not forgotten.

Can't answer the diesel question but here's what the side light business means as was told to me.

In Europe on small streets which are not lighted, these lights serve as a 'marker' if you will, so you car is not sideswiped. That's succinctly said in two lines.

For the 'long'-ston story, stay by!

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Regards . . . . JimF
-------------------
'94 S500 Cpe

Visit my Mercedes Web Page

In a gas engine there is a throttle which is restricting air flow at idle and while cruising. Inside the intake manifold between the throttle and the cylinders, the pistons are trying to draw air, but when the throttle is closed, or partially closed it cannot get enough air, thus it draws a vacuum, just like putting your hand over the hose of a vacuum cleaner. The throttle is necessary because the power in a gas engine is regulated by the flow of the fuel/air mixture.

In a diesel engine there is no throttle. The cylinders are free to draw as much air as they can get whether the engine is idling or at full power. The power is regulated by the amount of fuel that is injected into the cylinder. Since there is no throttle to restrict air flow, (no hand over the vacuum cleaner hose) there is very little vacuum created.


JimF is exactly right about the single side parking lights. The Germans have their act together about common sense safety. They are required by law to light the road side of a car that is parked after dark. This is most commonly seen in small towns. The streets wind around with very little room for parking a car, or to get by one.

The Germans, for the most part, actually follow these laws if you can imagine such a thing. In Germany it is a long arduous ordeal to get a drivers license. Because of this, they do not want to lose their license, thus they obey traffic laws. An additional reason that they obey traffic laws is because that by nature, most German people are obedient and orderly.

Have a great day,

Thanks for the replies, Jim and Larry.
The vacuum explanation makes perfect sense.
The signal lights...Are German drivers then required to keep these lights on all night long if parked on the street? Or are they only permitted to park on the street for a short period of time? I've always been concerned about draining the battery by leaving those on and I live in Southern California where it never gets very cold. I can't imagine leaving the signal lights on all night in a very cold climate.

__________________
Dave
1995 C280
1999 Triumph Daytona 955I - my speed fix.
1982 300TD - Gone, but not forgotten.

If it's parked in a way that requires them, the lights must be on while it's dark. They don't run down the battery, because they burn the lights dimmer than the regular driving lights. In Europe, I think they even have smaller bulbs for this purpose. The draw is minimal and if the battery is in good shape, there is no problem.

Have a great weekend,