1983 300SD electrical problems - PeachParts Mercedes-Benz Forum

adiaw83 · #1 12-17-2007, 12:30 PM

My 1983 300 SD had been running well until about a week and a half ago when the battery died on me. I took the battery to autozone, they tested it and the tester said bad battery. I purchased a new battery prorated of course and put it in the car. Back in business for the time being. 3 days ago, the car did not sound that good while starting. The starter was not cranking as hard as it normally does. On Saturday night, I was driving the car and the radio went out and the headlights started to dim. I tried to use the windshield wipers and they barely made it across the windshield and back. The speedometer needle would jump as I sat at stop lights with the turn signal on and the headlights dimmed every time I braked or the blinkers were on. I have not been able to start the car without a jump since this point. My belts had been loose for a while and I checked them out and saw that I had lost 1 of the 2 alternator belts. The other belt is still turning the alternator although it is squeaking as well. I have a multimeter but haven't been able to run any tests. Because it was not with me at the time. I replaced the started last year and the voltage regulator the year before that. Does this sound like a bad alternator to you all? thanks for the help

vstech · #2 12-17-2007, 12:35 PM

uh, it sounds like bad belts to me...

kerry · #3 12-17-2007, 12:41 PM

Replace the belts then get a voltage reading at the battery with the engine running.

tankowner · #4 12-17-2007, 12:47 PM

If you are losing power while you are driving, then the battery is not getting charged properly from the alternator. First thing first, make sure those belts have proper tension. You probably want to run her back to AutoZone and have them put a load on it and test the alternator and see if it is going bad. I had the same symptoms once before and I'm pretty sure I just replaced the alternator to fix the problem. Check the belts and then have the alternator tested and let us know how it goes. If that all checks out good then you might be looking at a parasitic drain, but clear the other options before going down that road. Good luck!

adiaw83 · #5 12-17-2007, 01:07 PM

Thanks for the responses. I won't be able to do anything until this weekend but I will post my results.

adiaw83 · #6 12-17-2007, 01:51 PM

One more thing. The heater motor has been out for some time now. It will come one sometimes and other times i can hear it but it sounds weak and will hardly blow any air.

vstech · #7 12-17-2007, 01:54 PM

welcome to the club on the blower motor... the buy parts link at the top of the page sells them for around 120.00, best price I have seen so far... where are the 25.00 new motors with the cage installed?

chetwesley · #8 12-17-2007, 02:50 PM

Are you the other me?

I had to check to make sure this wasn't my own post because aside from the belts on the alt, everything else you described is happening on my 83 300SD.

Check out this thread where a lot of this was gone through recently:

http://www.peachparts.com/shopforum/showthread.php?t=203111

adiaw83 · #9 12-17-2007, 03:09 PM

Thanks for the post chet. I think I am going to start with the battery terminals and work my way down from there testing as I go through each step. Hopefully it is not something too serious because it looks like you had to put a lot of work in.

toomany MBZ · #10 12-17-2007, 05:28 PM

Check this link. http://www.peachparts.com/shopforum/showthread.php?t=192846

Newguy · #11 12-17-2007, 06:10 PM

Before you loosen the alternator bolts, check to see if the alternator has any play.
I put new belts on mine because the old ones were loose and it had been a while.
Next day, belts were loose again. Then I discovered that the mounting hole in the bottom of the alternator was worn out. So, even though the bolts were tight, with the vibration from the engine, the bottom of the alternator would move.
This also caused strange problems like dash gauges going crazy and headlights flickering.
Thats because the alternator is grounded to the engine through this same bolted connection. So, I added a ground wire from the ground stud on the back of the alternator to the chassis ground. Strange electrical problems solved, even with the loose alternator.
I've got a replacement alternator on the way.

Good luck.

toomany MBZ · #12 12-17-2007, 06:37 PM

Quote:

Originally Posted by Newguy

So, I added a ground wire from the ground stud on the back of the alternator to the chassis ground. Strange electrical problems solved, even with the loose alternator.
I've got a replacement alternator on the way.

Good luck.

What car do you have?

adiaw83 · #13 12-21-2007, 01:49 PM

I just tested the battery and it was at 8.22 volts. The battery is a week and a half old. Once I get it charged and the car started I'll do a test do see what it reads.

Newguy · #14 12-21-2007, 03:01 PM

Quote:

Originally Posted by toomany MBZ

What car do you have?

Sorry, forgot to turn on the email notification.

Its a 300SD 1980.

Skid Row Joe · #15 12-21-2007, 03:11 PM

Sounds like the alternator should have been replaced at the same time the battery was. Been there done that on an '83 300SD. --Certainly, the belts should be replaced too.