babymog,

Ever hear of residual magnetism? That's the small amount of magnstism that remains after the electric current going thru an electromagnet is turned off.

If your theory was correct, an alternator would never work when a battery was dead. We all know that is not true.

Actually a gasoline engine starts easier with a roll start because the starter isn't causing a lower voltage to the coil so the spark is hotter.

P E H

First, the manual for the older cars says they, including the W114/115 cars, will all "push start" with automatics. It is not a recommended daily practice, but it will get the engine turning over at a speed that will generally address the symptoms of a weak battery or weak starter, or, as is usually the case, both.

And, long before the battery loses all charge, permanently and is actually dead, it will stop being able to perform the usual funcions, possibly even holding a charge. We typically call that a dead battery. But it will still do a nice job of partially exciting the alternator which is all that is needed if you get the car rolling above the speed it runs at with the engine at idle speed. And, the rotor of the alternator is likely weakly permanently magnetized as well, as PEH noted. This won't be enough magnetism to make full voltage but it will "bootstrap" the alternator up to full voltage if the thing spins fast enough, which, using the MB prescribed method shouldn't be a problem.

Jim

__________________
Own:
1986 Euro 190E 2.3-16 (291,000 miles),
1998 E300D TurboDiesel, 231,000 miles -purchased with 45,000,
1988 300E 5-speed 252,000 miles,
1983 240D 4-speed, purchased w/136,000, now with 222,000 miles.
2009 ML320CDI Bluetec, 89,000 miles

Owned:
1971 220D (250,000 miles plus, sold to father-in-law),
1975 240D (245,000 miles - died of body rot),
1991 350SD (176,560 miles, weakest Benz I have owned),
1999 C230 Sport (45,400 miles),
1982 240D (321,000 miles, put to sleep)

When I was little my grandfathers work truck had a very weak battery. Long story but he didn't want to change it, the truck was a 1986 F150 with a stick. It would run with a damn near dead battery, just needed a roll/push to get it going.

__________________
1999 SL500
1969 280SE
2023 Ram 1500
2007 Tiara 3200

gasoline igniton uses miliamps to run a car... its all about voltage.

__________________
Have you ever noticed that anybody driving slower than you is an idiot, and anyone going faster than you is a maniac?

As long as they would add one additional commandment for you to keep thy religion to thyself.
George Carlin (Wonder where he is now..)

1981 240d (engine donor 1983 240d) recently rebuilt engine hurray! - No more.. fought a tree and the tree won.

pearl black 1983 240d 4speed (Converted!@$$%) atleast the tranny was rebuilt.

It's a little more than that, but unless the battery is completely shot, there is more than enough energy generated by the rotation of the engine being push-started to operate the sparks.

__________________
'83 240D with 617.952 and 2.88
'01 VW Beetle TDI
'05 Jeep Liberty CRD
'89 Toyota 4x4, needs 2L-T
'78 280Z with L28ET - 12.86@110
Oil Burner Kartel #35

http://i16.photobucket.com/albums/b1...oD/bioclip.jpg

Cervan,

Yes, gasoline spark ignitions uses milliamps to run the car: Thousands of them.

There may only be milliamps at the spark plugs but there a few amps going into the coil. That's why the battery goes dead if U leave the ignition switch on. This may not be true of electronic igition systems but it was on the old point ignition systems. U could actgually see the ammeter move when the ignition switch was turned on if the points were closed.

P E H

Old300D,

It not the rotation of the engine that makes the energy to "operate the sparks", its the rotation of the alternator.

If the battery was completly dead and the alternator didn't work, a spark ignition engine would not start no matter how far it was pushed.

P E H

I know that. Push starting will turn the engine, hence the alternator. Obviously if the alternator is dead, you will not generate any electricity to spark the engine, but it works if you have a dead battery ( provided it's not internally damaged.) Older cars without computers would run without a battery, but newer ones need a certain battery voltage to operate.

__________________
'83 240D with 617.952 and 2.88
'01 VW Beetle TDI
'05 Jeep Liberty CRD
'89 Toyota 4x4, needs 2L-T
'78 280Z with L28ET - 12.86@110
Oil Burner Kartel #35

http://i16.photobucket.com/albums/b1...oD/bioclip.jpg

No, an alternator will always generate current, even into a completely discharged battery. It may current limit, and that can damage the alternator, but the alternator does not need a battery to operate.

__________________
'83 240D with 617.952 and 2.88
'01 VW Beetle TDI
'05 Jeep Liberty CRD
'89 Toyota 4x4, needs 2L-T
'78 280Z with L28ET - 12.86@110
Oil Burner Kartel #35

http://i16.photobucket.com/albums/b1...oD/bioclip.jpg

To all,

Do any of U remember the Chrysler ads when they first started using alternators? They ran a test car across the US without any battery in it. The alternator supplied all the electrical power necessary. Of course, they couldn't stop the engine and restart it.

P E H

I pull started my daughters 85 300D after it sat for about 14 hours in the High school parking lot one night after a ball game, it was some where around -15F. It works!

Key difference Gas vs Diesel: you DON'T need ANY electricity to run the vehicle if you can get it started. (unlike a gas vehicle, which requires some electricity to run the spark plugs) You can run the diesel car without the battery at all, in an emergency. The only problem in that circumstance is lack of electrical accessories, such as headlight, taillight, turn signals, which can be dangerous to lack. But in a post-nuclear apocalyptic raptue-on-outta-here world, where all the electronic ignitions have been fried by electromagnetic pulse from exploding nuclear weapons, it should still be possible to start and drive a diesel mercedes. With the standard transmissions that people have mentioned, push starting it is not a very impressive feat, as the manual transmission's drive train can be physically connected to the engine by releasing the clutch. With non-Mercedes transmission (and more modern Mercedes transmissions than my 123 deisels), I am not sure if it would be possible to hill/tow start the vehicle.

__________________
Der Panzermann und Fraulein Fahrvergnuegen

1991 420SEL 201K "The Big Blue One"
1985 300DT 205K chassis/285K engine nee California emissions "Goldbug"
1983 300TDT 255K "The Womble"
1983 300 DT 214K "Sea Sprite"-Rear-ended a truck
1983 300SD 285K "The Donor" Gave his life so that others can live
1980 500SL Euro 105K "Der Panzer"

P. E. Haige brought up that old advertisement of Chrysler and their wonderful new alternator. And it really was a great improvement over the generators we had for ages. But in 1966, when Oldsmobile brought out the Toronado, which along with the Cadillac El Dorado were the first American cars with front wheel drive since the demise of Cord in 1936. So Olds, for an interesting ad, hooked up their new Toronado to I believe an Air Stream travel trailer and drove it from New York to San Fanciso without rear wheels and tires as the basis for their ad. It did attract a lot of attention. I suspect they somewhat modified the equalizer hitch to insure that the unit stayed "in line" for the whole trip. It must have been a bit troublesome in 1966 to fuel up, because large Gas Station fueling areas as we now have, especially on the Interstate, were rarely available in 1966. And this was a very long and inflexible assembly. The price of gas was no problem though, as gas was typically selling for $0.31 cents a gallon.

__________________
Junqueyardjim
Christianity, if false, is of no importance, and if true, of infinite importance. The only thing it cannot be is moderately important. C.S. Lewis



1983 Mercedes W123 240D 4 Speed 285,000 on the road with a 617 turbo, beautiful butter yellow, license plate # 83 240D INDIANA

2003 Jaguar Type X, AWD. beautiful, good mileage,
Mom's car, but I won't let her drive it!

LOL, I remember when that car came out in '66, I was about 8 and my grandfather (who always bought a new Caddy every year) decided to get one. He hated it, it lasted about 6 months before he traded it for another Caddy. He wasn't exactly a "car guy."

Junqueyardjim,

I don't remember the Oldsmobile ad but I remember a similar one with a Chevy.

P E H