Alternator or just Voltage Regulator?
 

Hi everyone, on my way home i noticed that my cars dash lights were dimming, and then noticed my head lights werent to brighte either,, the dash lights were flickering a bit but never turning off,,, them my ASR and ABS and then the SRS lighst came on,, my radio started cutting out,, and then i pulled over,, to notice my car running very poorly, and it finally died.. My father came out to jump it and it was running fine until he took the cables off the car and it died about 20 seconds later... should i replace the altentor or the voltage regulator??

Model?

In a W124, failed brushes (regulator) result in no test lights in the dash with key in position 2

I had the same problem - went to talk to a guy about rebuilding my alternator. Said it would be $150. When I inquired about brushes he said he wouldn't sell them to me because if he did I'd be back next week needing a rebuild anyway. So I said goodbye... went home and ordered the $11 brush set from fastlane. Two years later and I'm still running strong.

Moral of the story - if you can wait a few days, at least give the brushes a try. It's only 11 dollars and it may work

Peter
1988 300e
1988 420sel

Your chances are excellent that the brushes/regulator will fix your problem.

Similar story here too Evan, my lights were dim, dash lights flickering, radio, SRS, etc., new regulator and everything is back to normal. Of the two brushes one was worn down to the nub and the other had about a quarter inch or less left on it. 15 minute fix.:D

Before you order anything...
 

Just check the regulator/brushes. It only takes 5 minutes to unscrew from behind the alternator. Go from there.

This may sound stupid, but im no where near my car right now and i need to know how big the two little bolts are that are holding the voltage regulator into the back of the alternator.... Also is there anything that i should watch out for when doing this job??

It would be most helpful to know what year and model MB "my car" is. Most of us here on the site failed the mind reading test.

If it is a 123 or 124 car, remove the VR and feel the sliprings on the rotor with your finger. If the brushes are worn in the VR and the grooves in the slip rings are no more than about 1/32 inch, then replace the VR. You can get one for $14 by clicking on PartsShop above.

Good luck,

Just had the same thing happen last month - stranded the Mrs.:eek: It was also about 5 degrees F outside and the car was 20 miles from home. Figured out it was the alternator but too far for a tow, didn't have enough tools, and too cold. In order to get the car home, I went to the closest part store and bought a new battery.

I could not find any local shop to buy a rebuilder kit and needed to get the car back on the road - so I took the alternator to a local auto electric rebuilder. When he put it on the test bench, it seemed fine! He loosed grip on the alternator and sure enough, no output. Apparently, there was enough wear on the rotor (and therefore the contact ring) that it was no longer making contact. It was a reman unit to begin with, so I don't know how many miles it had been in service.

In my opinion, with such a critical part that can result in getting stranded - it is worth the money to get it throughly checked out and either replace or rebuild. Simply replacing the regulator may be economical, but in my example it would not have been a long-term or reliable fix. Oh yeah, total cost of the rebuilt was $90.

In most cases I would agree. But with this alternator, the brushes and regulator are one assembly. You are not just replacing the regulator. You are replacing the worn brushes, which is almost always the problem when there is no output.

Takes five minutes. You don't even have to remove the alternator.

brewtoo nailed it. These alternators are absolutely incredible. I think they must be made of Kryptonite.

Not too long ago, at somewhere in the neighborhood of 230,000 miles the alternator in my 124 car stopped chargin for the first time in its long life. I pulled out the regulator and felt the sliprings. There was hardly any groove worn. I bought the cheap regulator here on the site and it has been fine ever since.

Not long before that I had put a belt on it. Whenever I replace a belt, I spin everything to make sure there are no rough bearings anywhere, so I know that the bearings in the alternator were still in great shape.

Because it is literally a five minute job to replace the voltage regulator and takes nothing more than a screwdriver, if you're paranoid about the alternator stranding you, spend fourteen bucks and keep a spare voltage regulator in the car. When the alternator fails, unless it has had the voltage regulator replaced many miles earlier, the odds are about 10 to 1 that this will be your problem.

The same alternator is used on the 123 cars and probably many more in the Benz stable.

You're not dealing with a Chevy here. These alternators are more long lived than the whole Chevy.

My $0.02,

Is this my problem too. No idiot lights on the left side. SRS and ABS lights come on a radio goes off. If i rev the engine they go out. Next day all idiot lights on(working). Lets hope its a bad wire on the regulator, or maybe just a clean. Is it best to disconnect the battery first. If so is it pos or neg to disconnect??
Oh yea, 88 W124
I will order a regulator from Fast Lane anyway.

I would think your voltage is low. Can't tell if it's voltage regulator, battery, or atlernator - but sound s like a low voltage situation.

limeyb,

This is very simple to check out. Put a DC voltmeter across the battery. It should read around 12 volts with engine off, then should go up to 13.5 to 14.5 volts once you start the engine and rev it up. If it stays at 12 volts, the alternator is not charging, but don't jump to conclusions and assume that the VR is the problem. It is very likely, but it takes five minutes to pull it and examine it.

Good luck,

The brushes on the alternator on my 190D wore out prematurely. We were on a trip when things started to quit. Fortunately, it was daylight and dry and that diesel just kept running when everything else went out.

I just kept driving to the nearest Mercedes dealer where they replaced the voltage regulator.