I've got a 1979 240D that I"m having some electrical problems with. It drove fine up until one day i went to start it and it just clicked over and over. I figured dead battery charged it overnight and same result. I tested the battery and it was still fully charged. To finally get it started I had to put the charger on start and hook up jumper cables and it finally cranked up. I drove it around and it was fine except the lights flickered a little when i turned on teh radio. After i shut it off it would'nt crank again not even click. I was thinking maybe it was the starter selonoid or voltage regulator do these sound like solutions? thanks

It may take a little more effort to narrow the problem down, but the very first thing you need to start off with if you're convinced the battery is good - is the battery connections.

It sounds like they are dirty and not making a good connection to the battery posts. The supporting evidence is your being able to start the car with jumpers, which grab onto the battery cables directly.

Whether it is ultimately the cause or not, you should take the battery cables off and clean the battery posts and the inside surfaces of the cable terminals until they are shiney. Then reassemble and coat with something to prevent corrosion. I happen to like regular grease, thinly spread.

If this doesn't help, then the next place to check for corrosion is where the ground cable hooks to the chassis - clean that too.

Ken300D

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

Providing the battery light is functioning normally the next time you start the vehicle try checking the charging system output. If the voltage is not over twelve volts at idle I would begin by disconnecting the "Glow Plug Relay" and see if the voltage increases.

If it is sticking it will cause all the output from the alternator to be consumed through the glow pugs.


My .02