Hey, i've got an 83 300D Turbo that's causing all sorts of havoc for me. First the car would hold a charge for about two weeks, then there would be a voltage drop on startup, then kaput, no starting. I replaced the battery and everything was fine for a bit, then it began to happen again. I let my mechanic take a look and he narrowed it down to and replaced the voltage regulator(Tuesday), which was reading incorrectly before it was replaced and correctly after it was replaced. Wednesday evening I stopped by to pay him for the tow truck and on trying to start it to leave the mechanic it wouldn't crank. This was accompanied by a buzzing from the glow plug relay so we replaced that, assuming that it was dead, indeed it was, and was burned inside as well, it looked like something blew and blew big time. Then about an hour ago, getting in the car at home to go to a cousins birthday party it was dead again. Any help would be appreciated, these Tow trucks do get expensive after a while. I drove the car my normal distance each time in between problems (about 25 miles)

Bob:

Dead battery or no crank? Do the lights go dim (or out) when you try to crank?

You have several possibilities here. You could have a bad battery cable, on either end, you could have a bad starter (shorted armature), or you could have a bad alternator.

I had a diode out on the 220D -- would have to charge the battery once in a while to keep it starting, and if I didn't, when I had to use the headlights the battery wouldn't stay charged.

I had it checked, it was bad, so I took it to the local rebuild shop (very good shop, incidentally) -- got it back with totally new guts -- both windings, diodes, and regulator were bad! Works fine now other than the usual "won't start below 32 F" problem that is probably the starter.

I suspect a bad alternator, just like mine -- do you have a battery charger? If so, just try to charge the battery (or have it done!) -- if it charges up OK, you don't have enough output to charge it in the car -- voltage will be OK if you have a diode or two out, but the alternator will only produce 10 or 15 amps (mine was only 4!) and the battery will go down each time you start until there isn't enough battery power to crank the engine.

Peter

__________________
1972 220D ?? miles
1988 300E 200,012
1987 300D Turbo killed 9/25/07, 275,000 miles
1985 Volvo 740 GLE Turobodiesel 218,000
1972 280 SE 4.5 165, 000 - It runs!

For what it's worth---just went through a similar, frustrating problem with my 1984 300 D. tried everything---new battery, alternator checks, you name it. On a lark, installed a new rear window defogger switch---thought the old one was shorting out and staying on all the time. Apparently, I got lucky. Have had no problem since installing the new switch. Also, check trunk light.