Weird Electrical Problem

[Ol'Smokey]

I am having a few electrical issues on my 81 240d. Shortly after I bought the car the alternator seized up one day so last week I put in a new one (reman). Tonight I was driving home from work and every now and then my headlights would get really bright and then dim back down to what I assume is the normal level. It would only happen once and awhile. Flare up, dim down, etc. Also a few days ago when I would turn on the lights my glow plug controller would make an inconsistant buzzing sound. It was fairly loud, I could hear it in the cab with the car running. But it would only do it with the lights on. It seems to have stopped doing that for now. Also my speedometer needle gets jumpy now and then. I'm not sure if these could all be related or not. The car has a new mercedes battery in it (october 2010), and as I stated above a new alternator. The battery connections are good, the battery ground cable connection is good, the wiring to the alternator is good and the connections on my glow plug controller are good. What do you think? Ground issues?

[layback40]

this sounds like earth connection problems. Best you check every connection to the body you can find. Also check the connections on the back of the alt. Clean them so you have a tight metal to metal contact.

[vstech]

and have your "new" alternator tested on the car. it sounds like a regulator issue as well...

[jbach36]

Plus, I have a W124, not 123 like you do.

If you have the old silver fuses, change them all to the newer copper ones. The old ones get pitted and (?) increase resistance, causing other problems is what I was told. I think I'm repeating that back properly. You can probably replace all of them for $12.

[jbach36]

If your speedometer is jumpy, if yours is the old type they used to have on most cars, you can probably replace it for $15-$20. You can try to lube it, but you'd need a very thin grease so it gets all the way down. Might be best to use Liquid Wrench Silicone Spray (not nut and bolt remover), as its sort of like an oil, very thin, but better.

[charmalu]

My guess on the spedo would be the cable. remove it and hang it up, then pour in some atf or lite oil and let it soak in. the cables are sealed so you can`t remove the center from the sheth.

Check the ground from the eng to body on the lower left side down low.

Charlie

[Ol'Smokey]

Thanks for the input guys. The connection on the back of the alternator is good, it's clean and tight. I will check the engine to body ground tonight. Are there any other major grounds anywhere I should check? Also, what kind of fuse's do I use to replace the old ones?

[Ol'Smokey]

Oh, I also checked the output of the alternator with a multimeter and it is right where it's supposed to be.