Dave just left, got everything done in about two hours. Replacing the regulator proved to be more difficult that replacing the whole alternator, so I went that route. He's still got some electrical gremlins to sort out but at least now the alternator works! Battery dash light never came on after the swap.

Seeing as how it's 2:30AM I didn't take any pictures, and we worked quickly. His starter seems to be toast, even jumping it didn't work. Probably a stuck bendix or bad solenoid. Cluster stuff also seems to have a bad ground or power source.

Overall it's a nice car! Definitely had some front end work done to it in the last few years, and despite having a bad starter we were able to push start it no problem.

Here is a common issue on the cluster.
http://www.peachparts.com/shopforum/general-information/296474-w123-instrument-cluster-printed-circuit-board-repair.html


.

Just wanted to thank you again Colin, and the rest of the board, you guys have been a great help for me. Unfortunately, I'm still having problems with the battery charging. The battery died on me the day after Colin put the new alternator on, which to me told me I just didn't charge the battery enough. So that night I put the battery on a charger, and I was able to drive the car yesterday. I was able to put on a good 45 miles around town, however later that night, after a trip back and forth from the airport, which is about 30 minutes each way, with the lights and the wipers on, I found my headlights were dim, and my sunroof struggled to shut itself.

So my battery is back on the charger now, and hopefully today I'll be able to test the battery a second time as well as the alternator. Since having the battery tested at Wal Mart I've run it down twice so it's possible that if it was holding a charge before, it's not now.

On top of the charging problem, I'm getting a rattling sound from the engine or something attached to the engine. When I listened under the hood it sounds like its coming from the lower passenger side of the engine. My oil pressure is a solid 2 at idle and 3 when I blip the throttle. I thought maybe my oil was low, it was down 2 qts but I topped that off, however the noise didn't go away. It isn't a constant rattle but it is relative to engine speed. What I mean is it'll rattle for a couple seconds and then stop, and start again after so many revolutions of the engine.

I took a look under the hood this morning and my belts look good. I turned the alternator cooling fan and it turns freely but then gets some resistance halfway through it's revolution. I really hope that's all that's causing the noise I'm hearing, or maybe my pulley is loose. I've gotta get this alternator off and see if the noise goes away after that. And then I still gotta get to the bottom of this charging problem. I will be inspecting the battery to block ground strap, the electrical connections between battery, starter, and alternator and see what's happening here.

Have you looked at this thread?

If there is damage to the circuit board, or someone installed the wrong cluster it can cause charging problems.

.

I remember you pointed that out, but it wasn't rattling before, it presented itself yesterday afternoon. When I first heard it, I thought it was something internal, which I guess could still be a possibility. How low would my oil need to be to do any kind of damage because that's what I'm most worried about. I pulled the dipstick and the oil was right below the low oil reading, so I topped it off with 2 quarts and its reading a little above the high mark on the dipstick. And what could that tranny line be hitting that would cause the rattle to be in sync with engine speed? It sounds like metal to me.

I guess the circuit board could be damaged, but as far as I know that's the stock cluster that came with the car. I'll take a look at the cluster when I get a chance. I very well could just need a new battery and that's why the battery is draining so quickly.

Was the charging voltage checked after the new used alternator was put in? It should be between 13 to 14 V. Autozone can test it for you if you do not have a DVM.

__________________
85 300D turbo pristine w 157k when purchased 167,870 July 2025
83 300 D turbo 297K runs great. SOLD!
83 240D 4 spd manual- parted out then junked

As there is almost no such thing as a turbo diesel with a manual from the factory, verify the ground strap from frame to engine is connected. Can cause all kinds of problems. I havent read anywhere that the alt charge was low...

__________________
http://superturbodiesel.com/images/sig.04.10.jpg
1995 E420 Schwarz
1995 E300 Weiss
#1987 300D Sturmmachine
#1991 300D Nearly Perfect
#1994 E320 Cabriolet
#1995 E320 Touring
#1985 300D Sedan
OBK #42

Also if you buy an alternator from Oreilleys get the higher priced one ,the replacement ones Id been recieving turned out to be for another car ,3 different times gets real old ,real quick.

^^I've seen a handful of this symptom at Pierre's shop when I've been there. It's not uncommon at all.

The more I think about it the more I believe there is some sort of electrical issue with the car. I told him that when he gets his vac pump done next week to have his mechanic take a look at the electrical system and make sure it's all functioning properly.

Interesting. And I know that alternator is good.

That rattling is that spare tranny line that's just hanging down there. I think I pointed that out the other night. You'll see it if you get under there.

Best guess..

Is it possible one of the alternator bolts worked loose, or the bracket lower front ear fractured?


.

If it were that wouldn't the belt be slipping?

Not always, if the ear fractured, it can cock at an angle pounding against the bracket.


.

Well I'll have to check it out, I just hope the sound is related to something external and not something internal

84 Mercedes 300d Turbo Rattling Sound - YouTube

I looked close and I could see the cooling fan for the alternator moving out of place when the rattle would happen.

I'm relieved because I thought I messed the engine up running it low on oil, but I need to figure out why the alternator isn't charging.

I couldn't get an alternator reading from the Bennet Auto Supply near myself, but when I shut the car off the battery was at 12.39V and had 760cca, it read that the battery was @ 80% so it's good, just not getting charged.

The weather, though sunny in the video, has taken a dramatic change and is thunderstormin right now, gotta love the sunshine state with it's summer "monsoon season".

Hopefully tomorrow or Monday I'll be able to check it out, I'll have to just put the battery on the charger in the meantime.

I may take the cluster out tonight and take a look at it to see if it's preventing the battery from charging.