Installed a 143A alternator in my W124 (86-95 E-class) - with photos - Page 2 - PeachParts Mercedes-Benz Forum

Zeitgeist · #16 11-20-2003, 02:30 AM

Well Dave, I may have glossed over the amount of effort I put into the alternator swap on my 220 D. It's been over a decade now, but I seem to remember dinking around with fabricating a new adjuster mount and shimming the pulley to run in line with the crank.

I guess the main point is for MB folks to think of all the Northern European vehicles out there as potential parts donors. Volvo, Saab, Audi, VW and BMW electrical parts can be interchangeable--within reasonable limits. The local pick-a-part here is usually full of Volvo 740's and Saab 900's, which have fairly high amperage Bosch alts. I think they charge $25--cheap.

BTW: Our Passat has a 120 amp alternator and is a serpentine system. Late model VW's might be a good alternative for the other OM 60X engines with serp setups.

gsxr · #17 08-21-2007, 11:53 AM

Bump for recent question... also updated links in original posts.

gsxr · #18 03-13-2008, 10:07 AM

TTT.

LUVMBDiesels · #19 03-13-2008, 01:17 PM

One comment... I was able to stick a AL129X from a Saab into my 300SD simply by swapping the serpentine pulley for my dual vbelt one. Why were you saying that it could not be done?

babymog · #20 03-13-2008, 02:06 PM

I noticed that the 150a alternator has a smaller pulley, did you leave that pulley on to let it spin faster at idle or did you put the stock '87 pulley on it?

I bought a 90a Bosch for the '87, smaller and lighter than the original, and without heated seats should be adequate for my uses, just wanted to get away from the low-voltage idling thing with the A/C on or all of the heated devices. It isn't as much the max. output that is inadequate (it is inadequate though), it's the low-rpm output that is dismal. Extra cycles on the battery.

Why do you want to increase your output voltage? Isn't 14.3volts excessive for a lead-acid setup? My big charger systems only use 14.3v as an "equalizing" voltage periodically, and it isn't recommended for sealed or no-maintenance type batteries as there is too much outgassing / water loss.

gsxr · #21 03-13-2008, 02:18 PM

Quote:

Originally Posted by LUVMBDiesels

One comment... I was able to stick a AL129X from a Saab into my 300SD simply by swapping the serpentine pulley for my dual vbelt one. Why were you saying that it could not be done?

I didn't say that.

I said the factory Mercedes alternators used with serpentine belts can't use the older V-belt pulley. The shafts are different. The 143A is AL0162X, the 150A is AL0766X.

The AL129X is not a Mercedes alternator, that's from a Saab. It was never used on any Mercedes. And yes, it works fine on an OM617 or M117 engine with V-belts. more details on the AL129X swap (for OM61x/M117/etc) are in this thread.

Photo of AL0766X (150A, Mercedes) - note the shaft length is very short:

Photo of AL129X (115A, Saab) - note the shaft length is much longer:

LUVMBDiesels · #22 03-13-2008, 02:22 PM

I see...

No worries

gsxr · #23 03-13-2008, 02:25 PM

Quote:

Originally Posted by babymog

I noticed that the 150a alternator has a smaller pulley, did you leave that pulley on to let it spin faster at idle or did you put the stock '87 pulley on it?

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.

Quote:

Originally Posted by babymog

It isn't as much the max. output that is inadequate (it is inadequate though), it's the low-rpm output that is dismal. Extra cycles on the battery.

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.

Quote:

Originally Posted by babymog

Why do you want to increase your output voltage? Isn't 14.3 volts excessive for a lead-acid setup?

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.

#24 03-13-2008, 03:12 PM

Quote:

Originally Posted by gsxr

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.

vstech · #25 03-13-2008, 03:52 PM

Quote:

Originally Posted by Craig

...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...

#26 03-13-2008, 04:25 PM

Quote:

Originally Posted by vstech

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...

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.

pawoSD · #27 03-13-2008, 04:35 PM

Quote:

Originally Posted by Craig

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...

iwrock · #28 03-13-2008, 04:54 PM

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?

pawoSD · #29 03-13-2008, 05:15 PM

Quote:

Originally Posted by iwrock

Do I just rerun new wires?

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

gsxr · #30 03-13-2008, 05:26 PM

Quote:

Originally Posted by Craig

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.

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.