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!