No, I used the stock pulley, which is the same on all OM601/2/3 diesel engines. You need to use the pulley that came off your original alternator. If the diameter is different, the belt length may need to be changed. With the original pulley, there's no problems here.

Exactly! And that's what my data showed as well. The 150A unit can put out a huge amount of current at idle, with no voltage drop like the wimpy stock alternator.

The stock 70A units have low output voltage (13.6 or so), and that is too low, IMO. Some new-technology batteries must have over 14.0V to reach 100% charge. However, the output of the 143A/150A units is fine, at 14.1V minimum. If people want to keep their stock 70A alternator, they might benefit from the adjustable regulator, which could be turned up to the low 14's. The higher voltage also helps your headlight output, etc. Mid-13's is too low, IMO, but low 14's is fine.

...or you can just use the stock alternator with an off the shelf battery and not worry about it. The stock setup is more than adequate unless you spend all your time idling or have some extra large electrical loads.

yeah extra large, like modern headlights, and seat warmers... extended glow plugs, oh, I don't know, maybe a decent stereo? yeah, those are "extra large" loads...

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John HAUL AWAY, OR CRUSHED CARS!!! HELP ME keep the cars out of the crusher! A/C Thread
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My drivers:
1987 190D 2.5Turbo
1987 560SL convertible
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1987 300TD
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Mine works just fine (no seat warmers) with a stock alternator. You know, we really don't have to try to re-engineer these cars every 15 minutes, the original designers did a pretty good job.

I would prefer a larger alternator so that I have higher voltage at idle, my afterglow stays on for 3 mins and the voltage barely gets over 12 even with the rpms up. Thats a lot of strain on the battery. It gets worse if I need the defroster blower and rear window defrost. I am going to scour the yards near here Saturday morning for a Saab 115A...that'd be perfect. And I could put in some new wiring/terminal block. Mine is old and in bad/corroded shape. (I do have a new one though...had to come from Germany! )

In the winter you do a lot of idling through traffic when its snowing....with all defrost on....headlights...fogs....stereo.....wipers....the power draw is very large.

I'll see what I can find this weekend...

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'15 GLK250 Bluetec 118k - mine - (OC-123,800)
'17 Metris(VITO!) - 37k - wifes (OC-41k)
'09 Sprinter 3500 Winnebago View - 62k (OC - 67k)
'13 ML350 Bluetec - 95k - dad's (OC-98k)
'01 SL500 - 103k(km) - dad's (OC-110,000km)
'16 E400 4matic Sedan - 148k - Brothers (OC-155k)

I have a 143 Amp alternator on the shelf of my garage, and have been wanting to do this swap....



The back of the stock alternator has plugs on it, not terminals...



Do I just rerun new wires?

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-Justin

91 560 SEC AMG - other dogs dd
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it's automatic.

Yes. Preferably heavier gauge ones...so they don't melt.

__________________
-diesel is not just a fuel, its a way of life-
'15 GLK250 Bluetec 118k - mine - (OC-123,800)
'17 Metris(VITO!) - 37k - wifes (OC-41k)
'09 Sprinter 3500 Winnebago View - 62k (OC - 67k)
'13 ML350 Bluetec - 95k - dad's (OC-98k)
'01 SL500 - 103k(km) - dad's (OC-110,000km)
'16 E400 4matic Sedan - 148k - Brothers (OC-155k)

I have detailed photos of the new wires I ran, see the links in the first couple of posts. Use 4 gauge (or two 8 gauge in parallel) as a minimum for 143-150A.

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The fact that I was able to generate a 130A load says a lot, compared to the 70A (peak!) output from the stock alternator. The designers did an ok job for the stock vehicle, at that time. In the early 80's, a 70A unit was ok. You'll note that most 124's were up to 110-120A alternators by the end of production in 1995. In the early 80's, high-output alternators were rare to nonexistent, so MB didn't really have anything larger to put on, nor any need to, at the time.

Anyway, my high beams alone (400 watts total) pull over 30 amps. The three Soundstream amplifiers are rated at 2000 watts total, with peak current draw in the 50-75A range (although typical current draw is relatively small, 10-20 amps at normal levels). Extra lights + extra stereo = Need Bigger Alternator.

Even with a bone stock vehicle, some of us don't like yellow headlights at idle, for example with the AC on high and the auxiliary fan running, on a hot summer night. Every 1980's MB I've owned with a stock alternator (and no additional loads) does this. I don't need to spend time justifying this upgrade. If anyone disagrees, hey, you're entitled to your opinions. I'm just sharing the info for the benefit of those who also need extra electrical power delivery. For example, the veggie oil crowd often add electrical heaters, which would easily overwhelm a stock alternator.

I forgot about that aux fan....in the summer when it comes on at idle in traffic it drags my voltage from 14 down to 12.5! And I don't even have A/C! I'd like to fix my A/C someday....so a bigger alternator is a must in all cases....I should have done it when I needed a new one but I did not have time to sit and re-wire the car nor search for a good priced 115A+ unit.

__________________
-diesel is not just a fuel, its a way of life-
'15 GLK250 Bluetec 118k - mine - (OC-123,800)
'17 Metris(VITO!) - 37k - wifes (OC-41k)
'09 Sprinter 3500 Winnebago View - 62k (OC - 67k)
'13 ML350 Bluetec - 95k - dad's (OC-98k)
'01 SL500 - 103k(km) - dad's (OC-110,000km)
'16 E400 4matic Sedan - 148k - Brothers (OC-155k)

That does not sound right, you may have a problem with that fan. I would take a look before you toast something.

OK, both my cars' lights are fine at idle with everything turned on, but I also don't have "off-road only" lights, a "pimp-my-ride" stereo, or any WVO crap. I do have a post-glow relay and relatively new batteries.

If you need extra electrical power for some reason, have a ball. I was just wondering why you thought it was necessary.

That depends how you define "fine". With a hot engine & alternator, and no loads turned on, check battery voltage. Probably 13.6v, give or take a few tenths. Which is not a problem. Now turn on the headlights, AC on max, and in force the electric auxiliary fan on (which runs most of the time with the AC in the summer). I'll wager a trunkful of WVO crap that the voltage will have dropped well below 13 volts. Wipers, rear defrost, radio, etc would add to it. This is normal behavior for a stock 55-70A alternator used on the 1980's models.

Some people may not notice it in the headlights, others do... with the load present, and at idle (stop light/sign), the lights will brighten noticeably when the engine is revved. Might not be as visible in the city, with lots of ambient street light. What pawoSD reported is typical, if you have a volt meter inside the car, so you can monitor it.