All of the indicator lights (from the battery icon to the ABS) on the dash turns on intermittently. It happened a while back (about 4 months ago) when I was stuck in traffic for 3 hrs, but when I revved the engine all the indicator lights would turn off.

The other day it turned on as I was on the freeway. I did a search on this forum and took out the regulator behind the alternator. The brushes were fine, but there were black debris on the diode (electronic part of the regulator). I cleaned it up and put it back in. All the indicator lights are now off, but it flickered on twice when I tested it earlier.

The engine runs fine whether or not the indicator lights are on. But the car does seems to lack electricity for the radio and lights when all the indicator lights are on.

I have a hunch my alternator may be bad, but why would all the indicator lights from the battery icon to the ABS turn on. I would think only the battery icon would light up if the alternator was bad.

What should I do?

jrmd01@yahoo.com

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JR
1986 Gold 300E 4Dr automatic

Yes...it is definitely the alternator...all the indicator lights on my car were on when the alternator died...when I revved the car up, the indicator lights go off one by one...if you think about it, most of the sensors for these indicator lights are electric...so when the source of electricity is low/gone...they would most likely report a malfunction also...I would get the alternator rebuilt or replaced...

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1995 black pearl/black Mercedes-Benz E420 :

The symptoms you describe are usually caused by an alternator fault. The warning lights are wired in such a way that they all illuminate until the engine starts and the alternator generates an output. This gives a warning lamp test at each start. Loss of alternator output will illuminate all lamps, not just the battery warning.

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107.023: 350SLC, 3-speed auto, icon gold, parchment MBtex (sold 2012 after 29 years ownership).
107.026: 500SLC, 4-speed auto, thistle green, green velour.
124.090: 300TE, 4-speed auto, arctic white, cream-beige MBtex.
201.028: 190E 2.3 Sportline, 5-speed manual, arctic white, blue leather.
201.028: 190E 2.3, 4-speed auto, blue-black, grey MBtex.
201.034: 190E 2.3-16, 5-speed manual, blue-black, black leather.

I'd throw a new $25 regulator at it before throwing a $250 alternator at it. If it's not the regulator, you have a spare.

BTW, did the brush contact surfaces have a similar wear pattern? Were they both shiny or was one dusty?

Sixto
91 300SE
87 300SDL
83 300SD

how long were they? Is this the original alternator?
Also, check your grounds and the OVP. Is your car running fine?

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J.H.
'86 300E

I am the 2nd owner of this 86 300E so I'm not sure if this alternator is the orginal one that came w/the car. Although I'm pretty sure it is.

The car runs fine whether all the indicator lights are on of off. BUT I do notice lack of electricity to my radio and lights when all the indicator lights are on (from the battery to the ABS)

I put in a new OVP (behind the battery) a few months back.

The brushes were both shiny w/grooves on the surface. The brushes were worn down unevenly. One was maybe 3/4 of an inch long and the other was about 1/2 an inch long. The shorter one was closer to the diode.

The diode was very dirty with black debris/grease (or something). It kinda looked shorted out. I was going to install a new one, but it cost somethng like $80 here in Hawaii. So I just cleaned out the orginal one. When I tested the car the other day (after reinstalling the cleaned up regulator) all the indicator lights flickered on twice. At present, all the indicator lights are off and the car runs fine. I'm just afraid that this is a temporary fix. I'd hate to get stuck somewhere. Right now the car is home and I can easily replace the alternator or the regulator if needed. I'm tempted to take a chance on a new regulator (vs getting another alternator). Where can I get it for $25 as someone said it cost?

Thanks to everyone who are replying. Your input is helping out a lot of people. I'm sure I'm not the only one with this problem.

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JR
1986 Gold 300E 4Dr automatic

That does NOT sound right!
Try to get a new one from FastLane, on top of this page. Just click on it and follow the directions. Support this site and save money at the same time!
Good luck!

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J.H.
'86 300E

I drove my car to an alternator/starter re-build shop. When I got to the shop, I heard weird noise from under the hood. The mechanic tested my battery and it was charging at 12.62 volts. He also noticed the noise and said that it was definitely my alternator.

Now, I'll do a search on replacing the alternator. I know there are 2 bolts for the alternator, but I'm a bit confused w/the tensioner.

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JR
1986 Gold 300E 4Dr automatic

The M103 tensioner is not for the uninformed. There's a long hollow 13mm nut behind the power steering reservoir and a 19mm head bolt under where the tensioner pulley and power steering puller almost meet. Loosen the 19mm bolt a couple of turns. Don't remove it or you're in for a heck of a time getting the tensioner back together. Then loose the 13mm nut until you can slip the belt of the pulleys.

When putting it back together, locate the indicator on top of the tensioner. Look behind the power steering pulley for a pointer near a triangle and a line. Hard to envision but you'll probably know it when you see it. Tighten the 13mm nut until the pointer is past the triangle and right at the line. Then tighten the 19mm head bolt.

I'm sure others will chime in with short cuts and torque specs.

Sixto
91 300SE
87 300SDL
83 300SD

I removed the fan shroud and looked for the 19mm bolt on the bottom, but I can't find it (feeling around with my hands). Part of the reason is that I can't stick my hand in there. Do I just stick in my 19mm box wrench?

When I took a look at the alternator bolts, I noticed that they were loose! I remember loosening them up when I was trying to fix one of the pullies. But after my failed attempt, I had a mechanic repair the damage I've done. The mechanic overlooked the loose bolts on the alternator.

I removed the lower bolt on the alternator and as I was loosening the upper bolt, the belt came off the alternator. I'm hoping that I can reinstall the alternator the same way it came off and not even bother with the tensioner.

Any advice/opinions???

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JR
1986 Gold 300E 4Dr automatic

This about as good a picture as I can take without removing the radiator. Looking straight down, you can see the tensioner body and just ahead of it you can make out the hex of the 19mm head bolt. If you view from this angle, you can guide a long 19mm socket into place. The view might not be as clear with the belt in place.

The belt is off the pulleys in this shot.

You can also see the pointer, triangle and line on the tensioner body. The pointer is about at 70% of proper tension in this shot. I'm not sure where proper tension is; either the end of the triangle, the gap or within the line. You can set it pretty precisely using the hollow nut.

Sixto
91 300SE
87 300SDL
83 300SD

Attached Thumbnails

 

Dear sixto,

thanks so much for the photo. A picture is worth a thousand words (and it answered a "thousand questions" too).

Thanks so much for your help. I'm sure your input has helped out many on this forum.

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JR
1986 Gold 300E 4Dr automatic

Thanks to everyone who responded to this post. (Esp sixto)
I saved hundreds of dollars removing my alternator and replacing it myself.

Total time from start to finish is about 30 min.
I just had my bosch rebuilt here in Hawaii for $150 (1yr warranty)
New was $700, authorized Bosch rebuilt $250-300
A mechanic wanted to charge me approx $120 for removal and replace - NO THANKS I'll DO IT MYSELF w/the help of supporters from mercedesshop.com.

Here is the details step by step.

1. Disconnect the battery
2. remove the cover from the back of the alternator w/8mm
3. remove wires on the back of the alternator
4. Loosen up the 17mm bolt
5. Loosen up the 13 mm tensioner bolt
6. Loosen lower bolt on the alternator
7. Loosen upper bolt on the alternator
8. remove the lower bolt on the alternator - belt can now slip off
9. remove the upper bolt - alternator comes right out.
10. put in new alternator and put in the upper alternator bolt
11. Put on the belt and the lower alternator bolt (you'll need a crow bar for leverage)
12. tighten up the 13mm tensioner bolt
13. tighten up the 17mm bolt
14 put back the wires behind the alternator
15. put back the cover on the alternator (8mm bolts)
16. reconnect the battery

I hope this helps someone else save $$$$$.

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JR
1986 Gold 300E 4Dr automatic

Most def the alternator. Get it replaced with the correct one because there are two for that particular model and year. If you have a totally electronic interior you need the higher end alternator. It's actually stamped on the blade of one of the fans.

I had the same thing happen to mee on the highway during rush hour. The bad news was, the battery totally drained and the entire engine, transmission, power and steering died and I had to muscle it off to the side of the road...

As a cosmoline-covered newbie I'm still learning local etiquette, so if I should have started a new thread, please let me know.

Thanks for the very detailed, clear instructions, jrmd01. I believe I'll need them if my diagnosis is correct.

I just bought an '88 300e. I've spent a lot of money fixing it up and it has been well-worth the effort. But as I fix things, there seems to be a cascade of processes or devices that were non-functional but hidden by the general fault of the larger system. Hope that makes sense.

For example, I just got the A/C working. I live in S. Louisiana, so I'd rather have a good A/C than four tires. FYI, the mechanic did a complete system flush and replaced various doodads and a leaking coupling before changing to R-134. I know it gets mixed reviews on this forum, but I'm a greenie and gotta stay true. The A/C gets the car cold enough for me and slows its fan after about 10 minutes after sitting in teh parking lot (this June as I write this note).

However, the load of running the A/C seems to drain the battery faster than the alternator can recharge it. It was dead as a boudin next morning. I jumped it off another car and it ran flawlessly, but I didn't run the a/c. It started fine after work for the (hot) drive home. When I switch the car "on" but before engaging the starter, all of the idiot light come on. When I start the engine the lights go off and then the engine catches quickly and one idiot light stays on--the washer light. I'm almost certain that's an unrelated problem--the sucker doesn't work even though over half-full. I can drive all day and run the windows up and down and the sunroof open and closed without affecting restart.

Using my VOM, I get about 12.5 volts at idle but don't know about amps, no ammeter and I don't recall exactly how to make a shunt...its been 30 years since I worked with electricity.

Is there a way to determine for sure whether my problem is the alternator?

Thanks for your guidance.

---chris