Alternator tensioner bolt, how to remove
 

Another newbie question. I am trying to remove the alternator on my 84 300 td wagon. I have the bottom bolt out, the wiring harness unnpluged, the belt tensioner backed all the way off and the belts off. It looks like the belt tensioner bolt goes through the alt. and needs to come out, but the threaded tensioner adjusting rod won't allow that. Does the bracket that holds the tensioning assembly come off with the alt?

If I remember correctly then the bracket does come off at the same time. I'm not sure this is the "correct" way but I believe it was the only way I could figure to get the alternator off (I did this about 6 months ago). Yes, it isn't exactly easy to get the alternator off.:D

the alternator unbolts from the main bracket. you dont need to undo the adjuster, just move the alternator toward the motor enough to get the old belt off and the new one on.

as i remember there is one bolt that attaches to the adjuster, 13 or 14 mm. this comes out and the bottom bolt (a big one) the bottom one often wears in the place the alternator sits so it comes out with a banded appearance. it might be hard to get out too because of this. the top bolt is usually easy to get out.

look at it closely it should become evident what needs to stay and what comes off with the
alternator.

btw, usually the brushes and regulator is what is wrong with the alt. maybe 75% of the time. so i would get it tested before replacing it. or i would just replace the brushes and reg first for good measure since it takes about 10 min and the r and r of the alternator takes at least prob an hour.

good luck

tom w

alternator
 

the cure to a bad alternator is to replace the brush assembly in the back of the alternator.... and you do not have to remove the alternator to do this...

Replacing brushes usually works, sometimes it's too worn and needs to be rewound, new bearings, etc. I know I couldn't get one of the bolts out on mine..... there wasn't enough room for it to come out all the way (But that may be specific to my year model).

americans
 

americans are all acustomed to replacing alernators....
and that is the first thing we do.... but if you have a mercedes
or volvo with a bosch alternator all you need to replace is the brush
assembly/voltage regulator... this is a little plastic item that screws into the back of the alternator... in fact you should carry a spare in the glove compartment... your alternator will last through probably 10 of these items..

and if your really cheap you can take your old one of these and solder in new brushes...:D

well i dont know about ten of them but it is usually the problem.

tom w

Well, I finally got it off and took it to Auto Zone for a free test. Bad alternator. A rebuilt is $90.00 for 85 amp, $120.00 for 95 amp, is that extra 10 worth that much more money? Thanks for the assistance.

_________________
84 300td wagon

blueranger,

I resent being called cheap. Frugal economical or thrifty is OK but not cheap.

P E H

Brushes and Regulator
 

This is stupid question, but are the brushes included in buying the regulator? I haven't seen brushes sold separately...how do I order them. I told you it was a stupid question...

Don

go for the 95 amp. it wouldn't hurt to go higher than lower. it might also help you to get your battery life last longer and brighter headlights even at idle with all the other electrical accessories like radio, wiper when raining hard, ac, etc...etc...

alternator
 

on the back of any or most bosch alternators you will find a
plastic assembly... it has 2 bolts holding it in place... remove the
2 bolts and go to the dealer or a foreign car speciality place and
buy the brush assembly. the brushes, and voltage regulator
are included in this one assembly.... then replace it and be on your
way.... you should really carry a spare one of these in the dash..

You can buy 2 brushes and unsoldier the back and soldier in the two new
brushes....

I have been driving foreign since about 1984 and I have not changed an alternator since back in the day...in fact this is a job you can do on your back at night with a flash light in the rain....

here it is
 

here it is the greatest invention since viagra


http://catalog.eautopartscatalog.com/mercedesshop/sophio/quote.jsp?clientid=catalog.mercedesshop&cookieid=1IZ1F9XRI1TM16OMYR&baseurl=http://catalog.peachparts.com/&partner=mercedesshop&year=1983&product=F4010-30110&application=000272329

I didn't think anyone saw me do that last winter!! ;)

The brushes are part of the assembly. Order a voltage regulator.
http://catalog.eautopartscatalog.com/mercedesshop/sophio/quote.jsp?clientid=catalog.mercedesshop&cookieid=1TH129NWZ1TM1DRIZ4&baseurl=http://catalog.peachparts.com/&partner=mercedesshop&year=1982&product=F4010-30110&application=000272327

i have
 

i have bought brushes and soldiered them in and i remember
paying 2 dollars.... little brushes with springs attached...
I dont remember where to get them but it was an electrical supply or
something.... maybe grainger but i am sure an internet search will
produce some brushes.

Brushes
 

are available from MB dealer for about $16. There are 2 styles. As soon as I get the ones I ordered I will post the part numbers.

Brushes are replaceable in Bosch regulators but maybe not in after market regulators. All U need is a soldering iron and solder to replace them.

P E H

blueranger,

U can't cure a bad ALT with a new set of brushes or V-regulator. U can only cure a bad set of brushes or V-regulator with a new set or bruches or V-regulator. Usually replacing the brushes or V-regulator will work, but not always.

If the ALT is NG, only a replacement ALT will cure the problem. How do I know this: I just replaced my ALT. I tried 3 different regulators and that didn't make the original ALT work. I then replaced the ALT with an ALT from another car and the replacement ALT is charging now.

P E H

Cut off
 

the cut off length for the brushes is 5mm. Pretty easy replacement in both 300D and 420sel.

I wouldn't waste my time trying to put new brushes in a voltage regulator. the piece costs just $25 from Bosch.

Well, I finally got it off and took it to Auto Zone for a free test.


I would put in a used Bosch original before I put in a rebuilt Auto Zone alternator--same holds for a starter.

Thanks everyone. Too late willie2004, the deed is done. I couldn't find a used one and I needed the wagon for a trip. After some head scratching, skinned knuckles, and some mumbling, I got it going. Only to discover another problem, now the speedo doesn't work, it was working when it was parked. The odometer, trip odometer, and the tach all work fine, but the needle doesn't budge. Any ideas? This blasted thing is rapidly ceasing to be a "fun machine", one wrong thing right after another. I expected to do some repair and maintenance, but this is getting ridiculous.

Ditto. Too damn easy to replace the regulator, and I've never seen a used one with bad bearings. Nothing else to go bad on them.

I haven't a clue about automotive electronics. AZ said the alternator had a bad diode(?) and the regulator was also bad.

everyone
 

everyone needs to know how to remove and replace the brush assembly... it is easier than changing your oil.... everyone here can do it.... :D

Important point regarding voltage regulators. the more recent Bosch alternators for the 123's are 65 amps. the original ones are 55 amp, and the voltage regulator for the 65 amp model will not fit, and indeed will crack when you try to screw it in. The proper regualtor for the 55 amp alternator is by some outfit, I think KAE, and cost me about $24

According to the Autozone website, AZ does not even sell an alternator for the subject vehicle.

Regardless of what a website may or may not say it WAS purchased at Auto Zone. It is not a stocked item and they had to order it.

Brush Part Numbers.
 

There are two different brushes that go in 55 AMP Bosch ALT that are on 617 engines, even though the alternators have the same Bosch P/N.

The MB part numbers are:

000 154 63 14 This is the type brush that has the braided wire attached.

000 154 81 14 This is the type brush that has a small stud attached.

Both brushes are available from MB dealers for about $16. I'm going to check with a Bosch dealer to find out if their price is lower. I will post when I find out.

Both brushes have to be soldered to the V-regulator assembly.

P E H

Old300D,

I never seen a regulator with any bearings, good or bad. LOL

Other things that can go wrong with ALT are the diodes, the windings and the slip rings. The diodes can either go open or short and the windings can and also go open or get a short thru the insulation. The slip rings can wear a deep groove from rubbing against the brushes.

P E H

Given the $25 cost of a new brush/regulator assembly, you'd have to be really short of cash and long on time to justify the savings on the brushes versus complete regulator assembly

Panzer,

Original V-reg was Bosch and there is a Bosch replacement available. Its more expensive than the non Bosch one available from Fastlane.

I just soldered the new brushes into the original Bosch regulator. Easy to do once I figured out how.

If anyone is interested how to replace the brushes with the braided wire, I'll explain.

P E H

everyone
 

everyone needs to carry a spare brush assembly in there glove box..
very important....

blueranger,

Yes, I agree everyone should carry a spare V-regulator and I do carry a spare regulator. However, sometimes its the ALT itself that goes bad and replacing the V-regulator won't help.

P E H

Probably a good idea, but I've never bothered to carry a spare v-reg because I can get home without it (in daylight, at least). I once had my alternator fail in the middle of Iowa, and ended up driving about 600 miles without shutting it off. As long as the brake lights work you can pretty much drive forever without an alternator.

thats true
 

thats true in a diesel you can keep driving.... my first experience with these were with volvos and i missed a christmas because of the v regulator....so from that point i started carrying one of these and i have changed many in the dark and in the rain....but it only becomes important in a diesel if you cut the car off....or its dark...

yes, everynow and then you will actually lose an alternator... although i have not lost one since 1984.... if you do loose an alternator do not replace it with an american alternator, Its better to have a 200k bosch alternator than a brand new american replacement.... the reason its better to have the bosch is because you want to be able to change the brush assembly in the future.. once you buy the american then your stuck replacing alternators from then on.

also on many of these bosch alternators they will have two belts, they are called a matched pair... I dont remember if the last time i replaced them if its this way on a mercedes... I think on the volvo you buy the matched pair and i think you just buy 2 belts for the mercedes....(its much better to get a matched pair)

This is a good idea. Carrying around one that may be old, but has not failed entirely is also possible. Probably possible to pick up one from Junkyard cheap. Alternatively, carrying around an old but functional alternator is another possibility. Again, one can probably pick 'em up in a junkyard and get 'em tested at Autozone or Checker. Of course, this is most relevant if you are going into the boonies (?Mexico) where spares might be hard to acquire. You can only carry so much in the way of spare parts. At some point, something will go wrong that cannot be easily fixed with stuff you are carrying!