Alternator woes - PeachParts Mercedes-Benz Forum

rrgrassi · #1 02-07-2008, 01:45 PM

Well, after replacing the battery last week, the alt decided to quit while I was heading out to lunch. At least the charge light dims when the RPM's increase, and goes out at 2500 RPM.

So, my question is...would you go with a 65 amp OEM alt or an 80-85 amp OEM used on a w123 gasser?

I do not really feel like messing around w/a McParts one.

Thanks!

vstech · #2 02-07-2008, 01:49 PM

have you checked the belts? how about the regulator? that would be my first choice before getting a new alt.

rrgrassi · #3 02-07-2008, 01:56 PM

Belts are good. I know the alt is pretty old, so I figured to play it safe, and get a new alt so that I know I get new bearings. Since I'm at work, no way to check the regulator. I do have a volt meter, and it was charging at 9 volts, at idle, with no load.

vstech · #4 02-07-2008, 02:48 PM

to check the regulator, you remove it. two phillips screws. look at the armature shaft. for major grooves... if the regulator has very short brushes, it needs to be replaced... there is a bunch of pic of a regulator on another thread posted today.
but, to answer your question, I would put in an 80 amp if i had my druthers..

rrgrassi · #5 02-07-2008, 04:15 PM

Cool, man, thanks! I'll check the brushes tonight after I get home.

rrgrassi · #6 02-07-2008, 04:42 PM

Looks like the Bosch AL68x is a 70 amp that drops right in. The AL69x is an 80 amp that needs a different connector on the back. Sheesh.

Well, 70 amps is a little better than 65.

The AL69x comes on the 380 SEL, but could also have the AL68x, depending on options.

LUVMBDiesels · #7 02-07-2008, 04:46 PM

Forget those low amp alternators. So a search on AL129X and see how easy it is to install a 115 Amp alternator in the car.

I did and never regretted it...

rrgrassi · #8 02-08-2008, 07:49 PM

If I can find one of those on the inexpensive side...

Anyway, I just got the Alt removed. The freaking voltage regulator was held in with slot screws, so it was not going to be just a "15 min. job". I had to bend the adjuster tabs to get the adjuster bolt out, but all in all it was not as bad as it could be..think newer cars.

I think I have the original alt, as none of the records I have indicate a replacement. I did pull the regulator just for grins...the brushes are completely worn down, and the armature has very deep grooves in it. The bearings are still free spinning, but you can hear them crunch a bit and the armature shaft does exhibit some lateral and end to end play. I have to clean the connectors, as there is some light corrosion on them as well.

So, now time to order the alt since I now have my core removed.

toomany MBZ · #9 02-08-2008, 08:40 PM

I replaced one at an indy parts store, the car died of other causes shortly thereafter, can't comment on it's longevity, but was told it used to be a Bosch. If you use a chain outfit, try and determine it's origin.
Most of those brackets have a bit of wear, but the adjusting bolts even more so.
Good luck.

rrgrassi · #10 02-11-2008, 10:32 AM

The alt fan is what kept the adjuster bolt from clearing the bracket. I'm going to shorten the adjuster a bit. I also removed the pully, and it did not just slide off. I noted the key way and had to tap it with a hammer a few times to get the pulley off. First alt I have ever seen w/a key.

New alt is on order now. I had to wait for the "big bills" to clear.

toomany MBZ · #11 02-11-2008, 03:38 PM

I had the fan hit the bracket, turned out to be broken, got a used one, put on the proper sized belts, working fine.