hi,my 89 300ce has a 70 amp stock alternator wich i think is a big sissy,its got all the power options the car could come with,i just replaced the alt with a new bosch,due to the fact that it needed one,but you kn ow my headlights still dim the dash lights still dim,does anyone know of any other benz alternators that can be cross fit,with a different pully,like 100-130 amps,i dont know anything about fitting other alts in place,is there a certain alternator from a certain model and year that will work on a 1989 300ce 70 amp stock,my battery just died and both alt,and batt are both new. im tired of lights dimmming,and forget about even putting rear defroster on,it sux up every amp the alt. puts out.thanks guys.marc

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Bosch AL65X is the original alternator, real world output was about 65-68A.

In 1990 MB realized that alternator was too weak as well & went to an alternator rated at 80A (Bosch AL66X). That is a direct bolt on WITH the later version wiring harness!
The AL66X puts out about 82-85A

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The 80a is too weak also IMO, my '91 would dim lights etc. at a stop when new.

A later car will have a larger alternator, I don't know when they changed. I bought an alternator from a Land Rover Discovery, it was either 110a Bosch or 130a, had to change to a bolt-on lug and heavier wire, and use the Mercedes pulley.

There is a thread I believe in the DIY stickys on alternator upgrades, a SAAB alternator is another favorite, if it's not in the sticky look in Diesel Discussion where it started and search for Alternator Upgrade (there are several but I believe that most point back to the mothership).

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Gone to the dark side

- Jeff

the 80 A alternator was also installed in the 126 300se.
Appreciable dimming of headlights with AC & headlights running were eventually diagnosed to the rectifier section of the alternator.
There are 6 main rectifier diodes and 3 exciter diodes working via the red warning light. if any of these smaller diodes goes marginally bad the alternator output is substantially reduced under load until rectified by replacement.
One indication may be a very faint glow of the warning lamp .

mak

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mark

Good info Mark, but from my experience they did this new, just not enough alternator when even my '85 Jetta had a 90a alternator as standard. My '91 had heated seats, heated mirrors, heated washer nozzles, heated rear window, lights everywhere, ... some of it can't even be turned off in cold weather and it wasn't enough to keep up at an idle. Many times I'd see my seat-heater switches and rear-defogger switch lights blinking which indicated that the voltage was too low and they shut themselves off, ... when the car was new. The VR did fail on that car when it was about 4y/o, a new M-B alternator had the same weak output at idle (which is why the auto-off circuits were on the bun-warmers and rear-defog, Mercedes knew that it was necessary). It clearly should have had a nice internally-regulated 110a-150a like all of its competitors were installing.

Upgrade, it's easy.

The end result is that your battery will last MUCH longer. Every time you idle and the battery discharges slightly (or it interrupts a charge cycle) it shortens the life of the battery, just the nature of a flooded-cell battery. The proper alternator will pay you back in battery life and warm buns.

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Gone to the dark side

- Jeff

yes i installed a bosch al65x,it sux,i will have to check into the other model described,anything is better than 68 amps.

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enjoy life,take the coal that is handed to you and turn it into diamonds. { PHILLIPIANS 4:13}

!90E owners with honkin' big stereo systems have found that S-Class alternators will bolt up to their engines with just a slight repositioning/rotation to accomodate the plug; these units are triple digit amperage.

Yes. MTI is correct. The 143 amp alternator fit perfectly fine on my 3L m103. It was aroudn 189-199 or so from Advanced Auto (lifetime warranty). The hardest part was dealing with the belt as I--at the time--didn't know how to properly release it.

It provides me with plenty of power all day long. It idles around 14 and under load is near 13.3 or so. (Load = headlamps, blower, big stereo system) The only time it dips below 13v is when the aux fans kick on (I wired mine to run at full power)

http://www.autozone.com/autozone/parts/Duralast-Import-Alternator/1995-Mercedes-Benz-S500/_/N-j1lhdZ9ci9i?counter=0&itemIdentifier=180914_125278_4761_

170$ from AutoZone

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i jus contacted the robert bosch corporation,and left a message with the claims dept,i told them the original al65x is highly overated,and that i cant even turn on my rear defrost without it killing my battery,im asking them if they will under the 12 month warranty take back the old 70 amp and replace it with the new al66x 80 amp alt. that should get me by,im not even running a stereo,i just want good headlights and a working defrost.

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