I'm new to the world of mercedes benz and to diesel cars and really hope you experts out there can help. I just bought a '78 240D with 59K miles. On a couple of occasions, I have turned the ignition key and had nothing happen - the engine didn't turn over and I didn't even hear a click (which I understand is the sound of a bad starter motor). This has happened when the car has been turned off for a relatively short period of time (less than 2 hours) and the temperature is in the 90s. The local mb repair shop says that the starter motor will sometimes "swell" and malfunction when it gets hot. The shop recommended that I bring it in for them to look at it, but I already took the car to a starter motor shop and they could find anything wrong. It seems to me that the mb shop won't be able to find anything either and that I need to wait until the problem becomes more frequent (if it does). Any ideas on what I should do? Thanks much for any wisdom or insight you have.

Probably the simplest and cheapest thing you could start off with is to clean all the electrical connections. Starting with the battery terminals, the ground cable(s), and the connection at the starter.

Not all that likely to be your problem, but certainly worthwhile to try this first.....

Ken300D

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1982 300D at 351K miles
1984 300SD at 217K miles
1987 300D at 370K miles

A good place to start is to be sure the Battery is in tip-top shape. Be sure terminals on the Batt. are clean and tight also. Then check the pos. connection at the starter and the grnd. connection at the body. If you scrape the grnd. contact point to bare steel, put electrical contact grease on it and tighten it back down with a star washer you then can be confident of current flow. An Ohmmeter is good to use here also if you have one.
Once you have this good electrical "foundation" you can then move on to the process of elimination.
I think I would next check for operation of the ign. switch and wire by checking for switched current at the starter solenoid.

P.S. Ken posted while I was composing, but we agree.

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Diesel-guy

I could also be a bad ignition switch or a bad neutral safety switch I had a bad ignition switch causing my starters to go bad by not letting enuf power to get to the solonid causing it to burn up the solonid. It happend to me.

Conanh,

Too many pronouns. What burned up?

P E H