bosch alternators
 

my alternator on my 1987 300e is shot. I want to buy my own alternator, and possibly replace it myself. I talked to a mechanic, and he said that bosch makes 2 lines of products, the kind they sell at pep boys/autozone (bad quality), and the kind they sell to mercedes. If i ordered from fastlane, or ******** az, would i be getting the higher quality alternator? Also, how much trouble is it to replace an alternator by yourself?

I'd go with the people that offered a lifetime warranty.............

Auto Zone will do just that, but you'll spend every other weekend removing the thing and taking it back.

Find a legitimate provider.

sure you don't just need the screw in regulator for 20 bucks?

I got a rebuilt Bosch starter for my Diesel truck from Track auto....now Advance auto for $85 ....everyone else wanted $250 (rebuilt).....that was 7 years ago....never a problem yet.

Highest price place doesn't guarantee the highest quality...or the least problems.

My dads F150 is on it's 4th Napa/Autozone alt. They don't offer a lifetime warrenty on his anymore, 3 years I think.

I just went through this, I ordered a $200 alt from Autozone and it wasn't even a Bosch rebuild, some China crap. It didn't even have the right shaft in it, I returned it and bought a proper one from Fastlane. Fastlane sells very nice Bosch rebuilds and it cost me $200.

I worked in an autoparts store for three years and saw lots and lots of perfectly good alternators getting returned as cores for rebuild. I really think there's little difference between the lifespan of rebuilt alternators. I think the biggest determinant of having a good experience from your alternator is by considering it as a "part" of your battery. A bad battery will kill a good alternator, and a bad alternator will kill a good battery. People get into vicious cycles and have no idea what is happening. Make sure your battery is holding a charge so the alternator doesn't get stressed, and make sure the alternator is putting out the correct voltage and current so battery doesn't get cooked. Unless the bearings or the windings are shot all you'll really need is the regulator. Two screws and you're done. It's not totally obvious how to diagnose a bad alternator. It's easier to diagnose a bad battery - charge it fully, let it sit overnight, and test it with a high-discharge tester (the kind that gets hot and has internal coils). An alternator needs a minimum voltage before it starts to work, so you can't charge a fully dead battery with an alternator...

Replacing an alternator is not all that difficult if you are comfortable with the operation of the serpentine belt. There's tensioner that is tucked away and has a 13mm hex fitting, near where the thermostat lives. Getting to a happy place with the serpentine belt is not effortless the first time you do it (or the second, third, or fourth times for people like me). Otherwise it's 3? bolts to remove the alternator from the housing, plus the wiring.

So to make a short story long, I'd go for the regulator and run a battery test before putting it in. (Also make sure your serpentine belt is tight enough. )That will confirm the diagnosis of a bad alternator and prevent you from killing a new alternator with a bad battery

I have seen a number of newly rebuilt alternators/starters/generators returned as cores as well. I contracted for a stint with a generally highly regarded remanufacturer. "remanufacture" process is much to be desired.

Process is as follows(at the location that I was associated with):

1. Remove cores from 55 gallon drums and teardown, then separate indiv. parts for cleaning.
2. Send parts through industrial cleaning machines of various design, depending on material.
3. Assemble "remanufactured" units with new bearings.
4. Send through "test bench" (means put unit in box)

Most all of the units reused brushes. Only the old Delco SI-10 was to get new brushes. Most popular units always got new bearings. Any less than popular units reused old bearings. Old bearings were sold to highest bidder for metal content.

Note: Units were put in boxes with more than one store/brand name.
Probably more than 1/3 of cores were clean units, 1/3 were rough junkyard leftovers.

If I have to buy a reman from somewhere, I have it tested before I even pay for it. I choose to repair myself or take to reputable electric shop- the one in my hometown largely was less expensive that the parts house (not always the quicky-part store, though).

Look for a company called National Automotive Charging. I worked eight years for a shop that was a dealer for their parts. I saw ONE alternator in that time had an early failure. Sadly it was my grandmother's car. not sure if they are still around. We carried their starters, water pumps, and starters.
Pricing was excellent. We could sell with good markup and be just over our cost from the parts house for the same application. Likely, if you find a dealer for them the guy at the shop will get you what you need for a reasonable price.

You might want to try to overhaul this yourself if you have time to keep the car down for a few days. You should be able to find the parts online doing a Google search for "alternator parts". You will most likely find that only one component is bad and in the worst case that would be a rotor. I got my Taurus rotor for under $30.00 the rebuilt price of an this alternator from Pep Boys was over $100. I will be willing to bet that you could get a Bosch rotor for under $75.00 and repalace everything else needed for a total of under $100,00. These are not difficult to rebuild but if you never did it before you may want to check out a book from the library to get familiar with checking diodes and other parts.

John Roncallo

quick question on bench testing
 

when taking the alt to be bench tested - will the testing test the alt it self, or the voltage regulator, or the combo of the two together?

DR88:

I have used rebuilt alternators for over 30 years and the only stipulation I would make is buy from a good source and/or with a good warranty. As usual, this must be balanced by cost. Most online parts sources sell the Bosch premium rebuilt alternators which have always provided me good service. Europartsdirect, whslparts, exprsautoparts, etc have them for $142 up.

As far as difficulty to replace, it is quite easy basically, depending on one's experience. If you want to try it, get instructions (I can send you the info from the MB CD manual).

As far as rebuilding the alternator yourself, I would say that it would require more experience than just switching one out, and quite a bit more time (depending on the extent of the rebuild you would do).

Finally, I just replaced the alternator on my 300CE - took me 3 relaxed hours. The prior owner had done the brushes/regulator thing and it lasted 27,000 miles.

Cary

Lofat:

Bench testing an alternator should test everything.

Cary

Thank you for the reply :)

Did my W124 alternator swap about three years ago. Took a week (casually removing old, waiting for FastLane to send new one, getting around to reinstalling, etc.)

Only kink in the project was having to get the pulley off the old and onto the new...didn't have an impact wrench back then, so I had to take it to a local shop, who did it for free.

Never a problem since.

Before you purchase a new alternator, determine what's bad.

Disconnect the battery negative, and unscrew the brush/regulator assembly off the rear of the alternator (has a T03-cased transistor). I would also remove the tension from the belt.

Inspect the brushes (are they worn down), AND the copper slip-rings that contact the brushes (looks inside the hole where the regulator assembly was).

Look for any wear or scouring marks. I use a small piece of 3M "blue" scotch-brite (not emery cloth that leaves deposits that can rust) to see if the copper slip-rings clean-up. If not, then you definitely need to rebuild/purchase a rebuilt one.

If it only needs new brushes, you can get the brush/regulator assembly for about $20-40 from this forum's sponsor: FastLane. Call them, it is not listed.

If your alternator is making a howling noise, it most likely needs new bearings.
You can either take it out, and bring it to a good alternator/starter shop (the ones that cater to the big diesel trucks usually are the best), and they will rebuild yours in a day.

OR, purchase a new/rebuilt one from this forum's sponsor: FastLane.

FWIW, I purchased a used one from a junkyard $60, and had it rebuilt $65 with a new brush/regulator assembly.

:-) neil