I have had my 240D for 2 years now and it runs great, but sometimes it does not wanting to start for no apparent reason. When this happens, the glow plug indicator still turns red and then when I pull the pull start to the start position the engine does not even turn, which indicates to me that it has to be an electrical issue involving the ignition system. Now, I have searched for the source of this issue and have not found a solution. The neutral safety switch, located under the shifter boot on the passenger side near third gear, has been removed and the connection for the switch has been bypassed by my mechanic. This seemed to work quite well until recently when the problem has reappeared. Now, I believe that the source of this problem has to be in the pull start switch. Also I have read about other people having the same problem as I have been having, but I have yet to read of a solution to the problem. If anyone has any suggestions of how to fix this please let me know.

Never had an automatic in one of those, so I am not certain what to do about the neutral safety switch. It is feasible the fix by your mechanic has failed, though.

On the manual version there was an interlock that required the car be in neutral to start, and if you forgot and pulled the stalk out of the dash to the start position, nothing happened at all. Not even a dimming of the interior light if you either had the door open or turned it on. This was a dead giveaway that the switch was not getting juice to the starter.

When the starter failed in that car the symptoms were quite the same except I would get a bit of dimming of the interior light when I pulled the stalk past the glow plug activation point. The switch is an expensive item to replace. In my car the glow plug position failed to light the little indicator on the dash, so I used the dimming interior light to time the glow cycle as the glow plugs were activated, it was just the circuit to the dash indicator that was bad. The same set of events happens, the interior light dims again, when you pull the stalk out to start and the starter engages.

So, if your starting issue is limited to nothing happening when you pull the stalk out, and there is no further dimming of the interior lamp as you pull the stalk out, the problem is either the neutral safety switch, or it is an electrical connection on the switch connected to the stalk, itself. You will likely need to check the schematics to figure this out. If the interior lamp dims further when you pull the stalk out to start, the problem is likely the starter itself.

Good luck,

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)

On my 220D my dad installed before I got it, a push button switch under the dash to activate the starter. The wires run directly to the starter and the battery. No problems in 20 years so far.

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1976 240D
1976 240D parts car
1970 220D daily driver

The car is a manual, I know that the interlock system is not in the car, and the bypass in the gear box is a clip thing that has a piece of metal in it that penetrates both wires and connects the circuit between the 2 wires with out cutting and splicing the wires. When the car doesn't start, everything works like it would if it were going to start except for the car doesn't start. So the glow plug indicator lights and when I pull the pull start to the glow plug position and then to the start position the lights do dim. I have thought that the connection between the pull start and the starter could be the source of the problem. So could it be a dead spot in the starter? Could it be just the pull start? How can I test the system to find the problem area?

hmm the lights dim, I'd get out and hit the starter with a hammer and see if it starts. plan on pulling that bugger out and rebuilding it or repalcing it.

I have hit it with a hammer one of the time that it has done this, but because of the infrequency of the car not starting I don't know if it that's a valid test. Plus I am usually alone when it happens. Also don't you need to have the pull start pulled to the start position when you hit the starter with a hammer? Does Advanced Auto Parts or Autozone test starters?

Our 220D would act very similarly, especially after long hot runs. I finally decided that it was either oxidized contacts at the starter solenoid or inside the solenoid. Particularly since the starter would often respond favorably to shorting the correct terminals on the solenoid with a long piece of 1" brass rod. However the starter was at times also awakened by providing a strong hammer jolt from above with this same brass rod. The jolt was done before attempting to activate the gorilla knob.

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1961 190Db retired
1968 220D/8 325,000
1983 300D 164,150

Sounds like you are getting power to the starter and it is ignoring your command to turn the engine over to start. Take it out have it tested by a repair facility. Used to be that local repair shops for starters and alternators were plentiful, not so much anymore. So, if you don't have one, buy a new starter or a rebuilt one from FastLane as they have good quality rebuilds, at least for the 240D/300D in the W123 body based on my personal experience.

Looks like they are about $170 from FastLane, with a $72.00 Core charge. Been a while since I replaced one on your chassis, but last time I did it it was January, the car was stuck in my driveway over a frozen puddle, and I did the job laying on my back under the car in 15 degree F weather. You are in luck as far as time of year goes!

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)

Heh, anybody else look at this thread title and think lawnmower?
my first thought was tow strap/bar starting with car in 2...