Hello:

First, I did a search on alternators and batteries, but did not find an answer to my question. And the question is... Is there a way to check the voltage regulator to see if it is bad or the windings in the alternator? I was wondering whether to buy the regulator assy or get another alternator?
Thanks

I forgot to say that it is for a 1986 300E.

[Edited by Ron Miller on 01-01-2001 at 01:36 PM]

Without the equipment to test on car no. But you can remove it and take it to most any part's house and the should be able to load test it for you, and free of charge.

You can check battery voltage with the car running and all the lights on, radio on, etc, etc. Note the voltage. Then, turn off all the lights and radio, etc, etc. Note the voltage. With a strong battery/alternator, the variation should not be much. It is a very basic test but, it will give you a rough idea where you are. Another thing you can do is take the regulator with brushes (they come as a unit) out of the back of the alternator (2 screws) and check the length of the brushes. When they are new, they are about an inch long. If they are short or close to the base, replace them.

There really isn't anyway to test the regulator except as a unit with the alternator. As such, one always takes a risk when just installing a regulator/brush pack.

Since a new/rebuilt unit will include a regulator this is where the risk comes in. I would suggest removing the regulator, examine the brushes, BUT pay close attention to the commutator ring where the brushes ride. If they are grooved heavily the risk is too great. The armature is probably only usefull for two sets of brushes and the second will probably last 50% less long.

Re-Built or New
 

Ron, I have a '87 300E and at about 150,000 miles I started to have low battery charge problems. The CHECK ENGINE light comes on with low voltage. The Regulator/Brush assembly was replaced. In the middle of a short trip the front bearing failed on the alternator the bearing had 150,000 miles too. A re-built from Pep-Boys was installed. After the trip the belt slipped. They broke the tensioner. Pep-Boys paid for the repairs. Another 3 months their alternator failed. Lifetime warrantee, pay the labor $57.00. Another 4 months, failed again, paid the labor. Another 2 months paid the labor, but arranged for a M/B rebuilt alternator, bought the M/B alternator but Pep-Boys would not refund my money only replace with their alternator, paid the labor. Now I have spent the cost of the off brand alternator and of the M/B alternator plus 3 labor charges. At last I had a M/B rebuit alternator. 6 weeks and the M/B alternator failed. M/B said it was a bad Battery all the time. I had a New Interstate M/B battery when this all started. It was replaced under warrantee but to an even higher capacity for a Benz. My Dealer contacted M/B and explained my troubles and M/B gave me a new alternator No charge. Troubles Fixed. You add up the costs, it makes me sick. At the beginning the Benz Dealer close to me the alternator was out of stock. Had I waited one more day? Do it again, NEW garranteed 12 months parts and labor world wide. Happy Trails Beep Beep from smarter now Houston.

Donald.
Newer than New

Thanks everyone for responding. Donald, I have had rebuilt parts too for my GM and Ford vehicles in the past. Most noteably, I have a 1986 Olds Delta 88 in the garage here. I had a shop put three rebuilt water pumps on in a 2 year period and then bit the bullet and bought a new one. The new one was bought in 91, and is still on the car today. I just looked at my Mercedes alternator, and there is a remanufactured tag on it. I may just spring for a new one now and hopefully eliminate many headaches.

One thing that puzzles me still, I put another known good battery in with 13+ volts. When I turn the key to on position, my abs light flashes 3 times and the o2 light comes on, but none of the other cluster lights come on? Is this because I still have a bad alternator installed? Or another problem?

Your lack of warning lights concerns me. The activation current for the alternator goes through the warning light/lights. It's possible that your alternator could not be "turning on".

In looking at a diagram low oil, low coolant, low wind/wash, low fuel, charge, brake, and low pad indicators all power up the alternator with power originating at fuse# 5. ABS and O2 are powered separately.

You need those lights to work for your alternator to function properly.

Bit The Bullet
 

Ron, your past luck is as mine. If you have any miles and/or years as I had on the original alternator, replacing the Regulator/brush assembly and the rest is original, well you get the picture. The only true way to test your battery according to what the Interstate Battery people told me, is to completely discharge your battery, then recharge at a low ampere input i.e. 1.5-2 amperes using an automatic charger that will reduce the input when the battery is completely charged. Then using a hydrometer test the specific gravity of each cell. The cells should test 1.275-1.300. The difference between each cell is to be no more than 0.025. My electrical problems are behind me, and what a good feeling it is. Happy Trails Beep Beep from Houston.

Donald.
fully charged

My #5 fuse looked ok, but I put in a new one anyway and no change. I noticed a spark when I disconnected and connected the battery today. So, I loosened my belt and turned the alt with the battery hooked up. Felt like there was a catch in the alternator. Also, the pulley was warm, and I had not started the car. I disconnected the battery and turned it again, no restriction at all. So I removed the alternator, hooked up the wires and battery, and grounded the alternator body on the exhaust manifold. It sparked. I held it tight against the manifold, and turned the alt again, felt the same resistance again, pulley got warmer, and I noticed the bearing end of the alt getting warm also. I took the alternator into the local repair all garage here, and their tester said it put out 10 amps through the regulator, and 18 amps without. He said it should put out ~70 amps. Also, he said it was whining bad, like when the triodes go out.

So after all the above descriptions, can the alternator cause all my problems, or am I going to have to replace the alternator and see what happens? Thanks everyone for your help and patience.

d.c. raltermotonator
 

Ron, have ever noticed labels instructing not to charge a dead battery with the engines alternator? The reason is for the alternator to operate it must had a minimum of 12 volts D.C. This voltage is to excite the field coils. Dead battery and no excertation, no out put. Low field coil volts and over worked and overheated coils. In your case the field coils seam to be excited from a failty regulator. Your alternator is trying to motor. Do yourself a favor and go to M/B for a new alternator(you will have to remove your old pulley and install it on the new alternator, and the new one doesn't use the pulley shaft key).Happy Trails Beep Beep from charged up Houston.

Donald.
no motor in my alternator

Well, another alternator fixed my problem. It's a good thing I didn't spring for just the voltage regulator and brush assy, because after removing my alternator and looking inside, the windings were fried to a crisp.

Ahhh, never the cheap way out for me it seems. But, my father in law, a farmer, I swear if it was his he would wrap a piece of baling wire around it and it probably would have worked. Ha ha. Thanks everyone for your help and responses.

Ron, you've just reinforced my buddy's saying "Good things aren't cheap, and cheap things aren't good. ;)

BCingU, Jim

Ron
 

As we all learn, the heart to our Benz is the electrical system. And it's heart is the alternator and the battery. Don't EL CHEAPO as I did in the beginning, go first class, use a NEW Benz alternator. Happy Trails Beep Beep from First Class Houston.

Donald.
the hard head
but no more

Ron Miller
 

No big deal, but in one of your postings you mentioned a Triode in your alternater. I believe it is a diode trio, or three diodes. Happy Trails from us dumbies Houston.

Donald
do it right the first time
and only once

I agree with Donald regarding alternators, I think.

I definitely think that buying a rebuilt alternator for your Benz from your neighborhood auto supply is a waste of money. I don't, however, buy them from Benz. I have had great success with Bosch certified rebuilt alternators and starters.

You won't go wrong with Donald's suggestion, but I think the Bosch certified rebuilt will also get the job done.

Everyone have a great day,

Yah and Nah
 

You read Larry's option. My experience has been just the opposite. Two B-certified rebuilt and two duds; probably the only ones in a ship load. You takes your choice. For something as important as an electrical component, and considerring the life of the part, NEW for me. Happy Trailes Beep Beep from Houston.

Donald.
The High Priced Spread Please.

Donald,

I'm sorry to hear of your bad luck. Maybe I'm due to catch up and the next one will not be good. I usually do not have good luck, so maybe I'm catching up a little.

I'm not totally sure where I got this idea, and I may be totally wrong. I think that the Bosch rebuilds are not done in Germany. They are done by various Bosch certified rebuilders in the states. They are independent rebuilders that are certified by Bosch.

Part of my job is running a program for Certified Integrators. In the software business, the integrator is the one who takes various software products, puts them in a pot and stirs to cook up the end users system. No matter how stringent the testing and certification procedures, some of them will be good and others not as good.

I'm wondering if this is why you have gotten bad ones, while the ones I've used have been great. You may be getting them from someone who is about to lose their certification, while mine have come from another one, who has their act together.

Anyway just a thought. You have me now to a point where I will at least check the MB price next time.

Thanks very much for sharing your experiences,

Don't Pep Boys and Kragen carry Bosch remanufactured alternators? I swore I saw them carrying them. Aren't they the same as any other remanufactured alternator or is it subcontracted out and actaully built worse?

s60 and Larry
 

Your right as to who besides M/B parts dept. sell The Real McCoyschtien, you can add Auto Zone as well. Considerring the life of the unit and the amortization, NEW for me. I recall some ball bearings falling in a quality control something or another. I guess I got the fall out. Happy Trails Beep Beep from Houston.

Donald
I got the duds

When it comes to rotating electrical Bosch rebuilds there own (I think). It is almost imposible to buy a new alternator or starter. The typical sale is rebuilt either from Bosch through MB or from Bosch through AutoZone.

We use almost no rebuilt products. The exception is rotaing electrical. I was checking an alternator for a 95 E320 yesterday and the MB price for a Bisch rebuilt was around $250 (I actually forget the amount). The new version was over $700. It was in the price sheet so I guess it was available.

stevebfl
 

You should know. The last alternator was installed by my dealer, weither it was new or rebuilt I don't know. I do know it was supposed to be new. And since M/B gave it to me nocharge and with a new warrantee, I'm just tickled pink. Happy Trails Beep Beep from Houston.

Donald.
Just another Dumbie.

Rebuilds and new alternators both come with a warranty, but sometimes the rebuild warranty is longer than the new one. No kidding.

s60
 

I'm pleased with whatever alternater I have, period. By the By when you get the pics of the Ram Air, you will see my New(rebuilt ?) alternater. Happy Trails Beep Beep from Houston.

Donald.
maybe it is a
Newrebuilt, or
Rebuiltnew,?

I have found that most poor quality equiptment come with the best warranties.

Warranties have very little to do with quality. They are a marketing tool. You can see this even from MB. They give all their rebuilt items at least the same if not more warranty. I think they warrant rebuilt engines the same as new cars now. A new short block probably has a one year warrantee as they know it needs none.

Take places like AZ and you find lifetime warranties. You might expect my opinion of most of their parts.

They do sell some Bosch though and if they warrant it for life more power to them.

Steve,

My memory is not great, so I may be wrong, but didn't I see some time ago that you said you have a Bosch rebuild center, or franchise, or something? If so what parts do you rebuild?

Have a great weekend,

Our business is a "Bosch Authorized Service Center" BSC. Bosch maintains an organization of independent repair shops throughout the world. It is a very old arrangement in the rest of the world. We were among the first shops authorized in the US in 1986. There are currently about 500 BSCs in the US.

Unlike the BAP program "Bosch Authorized Parts" specialist, the BSCs are hand picked, under contract, and are almost always state-of-the-art shops. The BAP program, which allows Bosch's name to be used by anyone who buys $200 worth of product, has no real relationship. We get training, information, and some tooling support.

Aside from our service relationship with Bosch, we are an "Authorized" Becker Audio repair facility. We also repair Blaupunkt radios and VDO instruments (mostly speedometers).

See: http://www.continentalimports.com

As to what parts we rebuild, I have a BS degree in engineering and work on cars because I've loved it since I got my first "Motor" manual when I was 14. I rebuild anything that is cost efficient (realize that is why we work on radios, speedos, and other electronics). I tend to buy no one else's rebuilts. We work on speedos because we couldn't live with the comebacks we got from sources we were using. We fabricate and rebuild all forms of machinery. This is the essence of being a "mechanic".


[Edited by stevebfl on 01-20-2001 at 11:33 AM]

Now I am confused.

In 20+ years of MB ownership, I have had a starter and a alternator replaced by a dealer. In both cases, they recommended rebuilts and there was no further trouble with them.

Last month, I bought a rebuilt starter and alternator for my 250C. The warranty info lists Robert Bosch Corp of Broadview IL and has the logos "Bosch Premium Quality" and "New Man".

I assumed at the time that I bought Bosch rebuilt parts. They came from Partsouth in Atlanta whom I selected because they were $70 cheaper on the order.

So, from what you guys say, are there different kinds of electrical rebuilts even though they come in a Bosch box with a Bosch warranty?

Chuck,

I've gotten kinda lost with this post. If it isn't clear, I'll give you my impression.

It is: that if you get an alternator from a MB dealer it will most likely be a Bosch rebuilt. Although almost all MBs use new Bosch alternators (there are other manufacturers; Motorola, Nippondenso, Valeo) when the car is built, only the first year or two are they available in the parts department.

Bosch alternators are rebuilt in many different locations. Many are in the US. They are likely to be the best rebuilt whether bought at the dealer or AZ. One confusing side of this is that Bosch is a manufacturer (what is called an OES original equiptment supplier)and a rebuilder. You can buy a "Bosch" alternator rebuilt by Bosch or you can buy a "Bosch" alternator rebuilt by Acme. You cane get a Nippondenso alternator rebuilt by Bosch also. They aren't proud they will even rebuild Delco alternators.

Bosch doesn't offer lifetime warrantees; they put their money into quality products not insurance.

[Edited by stevebfl on 01-20-2001 at 09:49 PM]

Steve
 

I too was aligned with an auto manufacturer,G.M. I am a graduate from G.M.I. I still remember first hearing of G.M.I. I was 15 years old and could only think automobiles and when I won my scholarship out of HighSchool, the first in the State of New Mexico I was on cloud nine. Anyway I spent 21 years with various divisons both here and abroad. A very rewarding carrer. I'm glad you told it like it is on rebuilds; they wouldn't believe any one else but your credentials speak for them selves. Ask about Fred Jones Ford in OK City to name just one. Happy Trails Beep Beep from Houston.

Donald
over or under the hill