loud buzzing noise under the air filter.HELP!!! - PeachParts Mercedes-Benz Forum

asti84 · #1 05-20-2007, 06:34 PM

I drove home last Friday and when I turned the engine off, there was a loud buzzing sound coming from under the hood. I couldn't figure it out but after a few minutes smoke started coming from the engine. I took off the battery terminal and the buzzing turned off. Before I did this, I tried turning the engine back on but the engine wouldn't turn over. I also observed the temperature gauge and it was around 80. I put back the terminal today and the buzzing sound came on again. Any guesses what this is.What should I do HELP!!!

THANK YOU FOR YOUR HELP.

1984 300d Turbo- 370K

Douglas.Sherida · #2 05-20-2007, 07:05 PM

I have no idea what it is but I would guess one of two things:

1) Aux water pump for the heater (black motor with coolant lines running to it, about the size of a skinny soup can). In front of and below the turbo, between the alternator and the fender.

2) Starter motor. Behind and below the turbo.

It sounds like something shorted out and is operating when it shouldn't be, especially since it stopped when the batttery was disconnected. I really can't think of anything other electronics below the air cleaner.

#3 05-20-2007, 07:12 PM

Sounds like a fried starter solenoid.

300SD81 · #4 05-20-2007, 07:22 PM

When my battery was almost completely dead, the glow plug relay started making a buzzing noise when I tried to start it, not sure if its a related problem, but worth checking..

PatricdeBoer · #5 05-20-2007, 08:13 PM

Sounds just like a stuck starter solinoid. Put the battery terminal back on, and if the noise starts again whack your starter with a pole or crowbar. If it stops, the starter is definitely your problem.

asti84 · #6 05-20-2007, 08:29 PM

thanks for your answers, we'll give your suggestions a try tomorrow...