My work requires me to drive to various different locations within about a 10 mile radius. I'm usually at each one about 5 to 10 minutes. I've recently taken to letting my car idle while I go into each site. It seems to me that this would be better for the engine than continuously stopping it and starting it every time I arrive and depart a location. Anyone agree or disagree with this idea?

- Peter.

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2021 Chevrolet Spark
Formerly...
2000 GMC Sonoma
1981 240D 4spd stick. 347000 miles. Deceased Feb 14 2021
2002 Kia Rio. Worst crap on four wheels
1981 240D 4spd stick. 389000 miles.
1984 123 200
1979 116 280S
1972 Cadillac Sedan DeVille
1971 108 280S

Others will be able to answer with more expertise, I am sure, but for 5-10 mins I'd let her idle, too. Easier on the starter, if nothing else. On long roadtrips in my TDI, I let her idle at rest areas and short meal stops, etc... she's covered more than 500 miles w/o once being shut down before. When I am traveling alone, I carry a spare key to lock the door and a "Club" for the steering wheel; at least it's a little less tempting to smash & dash that way, and it may be a bit less of a liability too.

How *is* the pizza delivery business, anyway? (Just kidding )

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1992 300D 2.5T
1980 Euro 300D (sadly, sold)
1998 Jetta TDI, 132K "Rudy"
1974 Triumph TR6
1999 Saab 9-5 wagon (wife's)

I'm in the 'let idle' camp also, keeping a spare key in the car for just that purpose.

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1977 300d 70k--sold 08
1985 300TD 185k+
1984 307d 126k--sold 8/03
1985 409d 65k--sold 06
1984 300SD 315k--daughter's car
1979 300SD 122k--sold 2/11
1999 Fuso FG Expedition Camper
1993 GMC Sierra 6.5 TD 4x4
1982 Bluebird Wanderlodge CAT 3208--Sold 2/13

I would idle it too. You could always unplug the vac line from the fuel cutoff and take your keys with you. I've done that before.

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1979 240D- 316K miles - VGT Turbo, Intercooler, Stick Shift, Many Other Mods - Daily Driver

1982 300SD - 232K miles - Wife's Daily Driver

1986 560SL - Wife's red speed machine

Is there any negative impact from having the alternator turning with the ignition key in the off position?
I began to wonder this a few weeks ago when my shut off required sucking on the hose sticking out from the hood. I'd turn the key off, lock the doors, then suck on the hose to shut it down. Was I diverting the electrical currents in any detrimental ways?

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1977 300d 70k--sold 08
1985 300TD 185k+
1984 307d 126k--sold 8/03
1985 409d 65k--sold 06
1984 300SD 315k--daughter's car
1979 300SD 122k--sold 2/11
1999 Fuso FG Expedition Camper
1993 GMC Sierra 6.5 TD 4x4
1982 Bluebird Wanderlodge CAT 3208--Sold 2/13

just carry an extra key with u to lock the doors " as long as ur in a somewhat safe place where people arent going to steal ur benz" it will save the starter and keep your battery charged!

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82' 300SD

I wouldnt know. I'm a PC tech for a school district. But the "Pizza Dude" might just be doing better than me...

- Peter.

__________________
2021 Chevrolet Spark
Formerly...
2000 GMC Sonoma
1981 240D 4spd stick. 347000 miles. Deceased Feb 14 2021
2002 Kia Rio. Worst crap on four wheels
1981 240D 4spd stick. 389000 miles.
1984 123 200
1979 116 280S
1972 Cadillac Sedan DeVille
1971 108 280S

Not that I can think of. You just disconected the exiter circuit of the alternator by removal of the key disabiling the alternator charging while you were away from the car I believe. As soon as the key is inserted and turned back on so is the alternator. You could verify this easily if you read the voltage with the key on and off while the engine is running if you wanted to. The main item is no harm is being done really in my opinion. Now the qualifier. This approach should never be attempted on a modern diesel setup. For starters only the alternator is usually linked to the computor.