81 240D electrical problems
 

I posted this in both 'Tech Help' and 'Diesel' forums, looking for help on this one. the niece wanted to 'drive' down the driveway so she gets behind the wheel and I start it up (4 speed) and she lets out on the clutch too fast and kils it. when i try to crank it back up, i get this odd sounding buzzer (not the normal inside buzzer sound) when the key is turned to 'glow' and then nothing when i go to 'start' with the key. the glow plug box on the front left fender well growls when the key is on 'glow' and the lights are dim. I've cleaned the grounding strap from the bell housing to the chassis as well as the battery cables/terminals. I've switched the aux fan and starter relays on the front left fender well to check those but nothing. ANY IDEAS?

Is the transmission in neutral and the clutch pushed to the floor ? Are your seatbelts fastened ?

clutch/seat belts
 

clutch wasn't depressed and seat belts were not in BUT, that's never been a requirement. it would/will start with the tranny (again, manual) out of gear and no 'foot on the clutch'. what puzzles me is the 'black box' on the drivers side fender well buzzing or growling when the starter switch is in the 'glow' position. Might be able to get one off of a parts car and replace it, if that works, I"ll post it. I've put 140K on the car and this is the FIRST time it's ever NOT started. Hope to put lots more on it. I'm about to the point of just getting my meter and starting at the battery and work out if the replacement doesn't happen.

Sounds to me like you have a relay or some other electrical connection loose. The buzzing is possibly a low voltage indication. Confirm by using your multimeter at the power supply to the glow plug relay (the thing you described making noise). If there is a voltage problem check to see obvious connections are not loose or corroded, or not fully engaged in a plug socket from the driveway experiment. I would check the battery terminals, the battery ground strap and go from there. Jim

closure
 

after much hand wringing and general crawling all over/under the thing, I followed my gut instinct and started at the battery by taking it to a buddy that tested it.........lo and behold, it was bad. replaced with a new one (that one was only about 3-4 years old) and it's back to its old stinky, noisy, slow chugging self.........320k and counting. :)

What was the buzzer sound ?

re:buzzing
 

The 'inside' door/starter buzzer sounded like it had a terminal illness. The one under the hood (front left fender)was the glow-plug relay and when I say buzzing, I mean it was almost a growl. With a failed cell (ground) in the battery that would mean a 'low-voltage/high current' situation provided that any voltage at all was getting to it, which it was based on the racket. I"ve talked with a mechanic friend who works on Mercedes and he said that a battery going bad can do really wierd things. He told the account of one he worked on that the guy was driving down the road and all of a sudden the dash lights came on (glo-plug, brake, etc. ) along with the 'inside' buzzer and the wipers. The battery 'went bad' and generated who knows what kind of currents through all sorts of things. Burnt up both wiper motors and some relays under the dash, so I consider my self lucky............