Installed a 143A alternator in my W124 (86-95E-class) - with photos
 

Hi all,

This is not a "question" post, this is just a summary of what I did to my car, and thought it might help others as well. Due to large bulbs in my Euro lights and a hefty stereo planned, I needed more output. I picked up a 143A alternator from a 1998 S420 and experimented with it. I swapped my original pulley onto the 143A unit because the S420 pulley didn't stick out far enough. Otherwise it bolted right up - same mounting brackets, bolt spacing, everything. The new unit is larger and comes pretty close to the lower radiator hose but doesn't touch. So how does it perform? Read on:

I got the car fired up and tested the alternator output. Remember, my stock unit was 70A and had what appears to be two 10-gauge wires to the junction block near the battery. The new one is a 143A with a zero-gauge cable to a new distribution block and to the battery. I tested full load by turning on every electrical item I could, measured voltage with a Fluke 12 VOM, and current with a Fluke 36 DC clamp meter. All tests were done with a "hot" alternator, after driving the car at least 15 minutes with a decent load.

The stock unit could only cough up about 45 amps at idle, but did put out around 75amps maximum (revved up to ~2000 rpm). Voltage was poor... Never got higher than 13.6-13.7 volts even under light load or no load. Under moderate load it drifted down to lower 13's, and at peak load it went below 12 volts (!) as the alternator simply could not put out the power. :(

The 143A unit could put out roughly 100 amps at my ~600rpm idle speed, and appeared able to put out max current at barely above idle, not even 1000rpm! :D The highest load I could generate, including some current to charge the battery, was 125-130 amps. At 1000rpm, it put out the 130 amps and did so at 14.1 volts! And at idle, same thing, 14.1 volts (with a smaller load, under 100 amps.) The only time voltage dropped was with VERY high load at idle and I don't think I ever saw it go under 13 volts, and that was with an "artificial" load that is unlikely to occur in normal use.

My "normal" load is low beams (90Wx2) and ACC fan, plus whatever the chassis electrical stuff pulls (EDS, gauges, etc.) This appears to be roughly 40 amps, plus some current to charge the battery. The good news is, with my "normal" load I get a solid 14.1-14.2 volts, even at idle! VERY nice. I'd like the voltage a bit higher (14.4-14.6) but there is not an adjustable regulator available for the 143A unit (AFAIK). No big deal, I'm happy with the setup as-is. The stock unit badly needs an adjustable regulator, and I'd highly recommend one for those of you not interested in the full big-alt swap. Set it when stone cold to 14.6v or so, it will drop a bit as it gets hot, and you want to set the HIGHEST point.

The only down sides are extra weight and horsepower loss. The 70A unit weighs about 11.5 pounds, the 143A unit is 16.8 pounds. Not a big deal. But when you spin the shaft of the 70A unit, it feels light and spins easily. The 143A is MUCH heavier (massive) and definitely takes some extra crankshaft power to spin, even with no electrical load. I'd guess it could easily sap 3-5 HP more compared to the original. Still worth it, IMO.

Verdict: Would I do it again? Yes. I already bought another 143A unit & new pulley, and plan to install that on my other 1987 300D in a few months! :cool: For the record, a used 143A unit can be bought used for ~$75-125 or so. The donor car must be a 1996-1999 S or SL class with a V8 (SL500, S420, etc.) Others may work but I don't know what years & models, and most others are smaller (100-120A).


Photos of everything are here (nothing new from last time though):
http://www.W124performance.com/images/W124_stereo/

I'll post a few photos below this, if I can find one small enough to squeak by the 65kB limit... :rolleyes:



Regards,

Here's a shot of the 143A installed, before the wires were connected:

OK, well, the forum won't let me post any other photos because they are larger than 800x600, and I'm not going to re-size them all. Just click on the link below and see the photos for yourself:

http://www.W124performance.com/images/W124_stereo/

:D :D

Regards,

I have a 190e I want to upgrade the Alt on. My 65A is not working properly and since it needs to be replaced, I am thinking I may just install a high output Alt. It looks like you may have a 190e in your stable. Does it look like the 143A alt will fit in the 190 series?

I just got my car running great and now am starting my long list of custom upgrades (which includes a complete onboard LINUX based computer system). I will need more serious amperage to support my dream machine.

Rich, assuming your 190E has a serpentine belt (which I believe it does), the alternator should bolt on. You will probably need to use the pulley from your old 65A but otherwise it should work. You'll need to beef up the cable to the battery, I'd use 4ga minimum (or a pair of 4ga), better yet use 2ga or 0ga. So far I've been really happy with my setup, I plan to install a second 143A on my other car too! :D :D


Good luck,

Thanks. I do have a serpentine belt and I will be on the hunt for a 143A tomorrow. I need to get this fixed ASAP (in fact I was thinking of buying a new 65A.. just to get the car useable.. but my wife said "no way..Fix it once only". I guess she is right. Thanks again.. I will post my results.

What I *really* want to know is how Dave keeps those old diesel engines so clean. My 603 isn't bad, but it sure don't look like that!

- JimY

Heh-heh.... thanks! :D :D Mostly just some engine cleaner from McParts, and a trip to the coin-op car wash to blast stuff off... more photos here:

http://www.W124performance.com/images/OM603_head_replacement

:) :)

Since Richbark has not posted his results yet, I will post mine. I installed a 143amp alternator in my 1993 190E 2.3. I got the alternator from Pat at Potomac German Auto.

The 190E originally had a 70amp alternator. I swapped pulleys and rotated the rear housing so the wiring would line up. It fits and works perfectly! I have not upgraded the cable to my battery yet, but it seems to be working fine for now.

I don't have any pictures yet or any power measurements but I will try to get those this week.

Thanks again for the research Dave!

Regards,

Don

No problem, Don! Glad to hear it also works on a W201/M103 setup as well... :) :)

I have a M102 but it should work on a M103 with no problems also.

Whoops - that's whay I get for typing a reply too early in the morning. ;) You sure do have the M102. Oooops! :eek:

I got some photos of the 143A and 150A alternators side by side (click links below). Note that the 150A unit is slightly larger, and has a lot more venting in the case. Interestingly, the 150A is a half pound lighter, possibly due to the larger vents (16.25 lbs compared to 16.75). Also note the ratings on the nameplate. The 143A is rated 73-143A, the 150A is 90-150A. The first number is the alternator's rated output at ~1800rpm shaft speed, the second number is output at ~6000rpm shaft speed. That is NOT engine speed - you need to measure your crank pulley & alternator pulley diameter to translate that into engine RPM. On a side note, Bosch's website claims they now offer "Bosch Sport Compact High-Output Alternators" with outputs up to 200A, specifically designed for people like us with current-hungry ICE and Rallye lights. :D But I couldn't find a damned thing other than the press release, so I have no idea if they make a bolt-on 200A unit for our MB's.

Also: WorldPac now has the 143A and 150A alternators available. The 143A, with core (assuming you are upgrading and don't have a bad 143 to return), is ~$300. The 150A is closer to $400, which is nuts. Check with Rusty (800-741-5252, ***************) if you want a fresh rebuild. Or you can score a used one for $100-$150 if you check around enough.


Here's the photos:

http://www.w124performance.com/images/W124_stereo/alternator/150A+143A_1.jpg

http://www.w124performance.com/images/W124_stereo/alternator/150A+143A_2.jpg

http://www.w124performance.com/images/W124_stereo/alternator/150A+143A_3.jpg

Hi all.

Anyone know if it will fit a W123 diesel?

Louis.

I think this was posted earlier in the thread, but if not.... No. The big alternators fit MB engines with serpentine belts. So far, nobody has figured out a way to convert a late model alternator to the old V-belt engines. If you can do that, you'll have lots of people wanting to know how you did it! :D

im sure this is a pretty stupid question,but im going to ask anyway....could you possibly convert all the existing pulleys to accept a serpentine belt,and just convert the whole pulley system?

That would be the best solution, of course! But so far, nobody has figured out how to swap OE parts to the older engine to make everything serpentine with an automatic tensioner, or created an aftermarket kit either. It would be easier (most likely) to have a custom pulley made for the big alternator, assuming you could find a way to mount the blasted thing - it's a LOT larger (I think) and the mounting points are very different. And, the V-belt setup requires the alternator to move for adjustment. AND, someone else pointed out that V-belts might slip, and not have enough friction to drive the higher load of the high-ouput alternator. Lots of "gotchas" with the whole concept... :( :(

Alternator upgrade on '92 500E???
 

hi,

I like knowing first; what the stock alternator output is in my 500E and if its a good idea upgrading to a higher output alternator. thanks

Hashem,

Your 500E probably has a 110 or 120A alternator. You don't need to upgrade unless you have rather large auxiliary electrical loads, such as a killer stereo system, or megawatt headlight bulbs (100-130W in all 4 spots). Besides, I'm not sure how easy it would be for you to source a cheap 143-150A unit outside the USA... and the cost new is insane. :eek:

Re: Installed a 143A alternator in my W124 (86-95E-class) - with photos
 

Excellent Mod, thanks for the info. I once did something very similar to my old RX-7.

BTW, Don't worry about the voltage at 14.1. That is exactly where you want it and the voltage regulator seems to be working perfectly. Any higher and you'll generate excess hydrogen gas and sulfate up your lead plates in your battery. 14.1 V is exactly the right voltage for charging batteries for best life, especially since you'll have very little voltage drop between your alternator and the battery with your new cables.

Also, to figure out how many ponies are robbed, lets do some math: Since Power = Volts * Amps, Power = 14.1V * 130 Amps = 1833 Watts. 1833 Watts = about 2.5 hp. Assuming about 80% effeciency for converting mechanical energy to electric energy (fairly conservative estimate), and that's 2.95 hp.

Hmmm, I'm a mechanical engineer, not electrical...how do I remember this crap?

143
 

Does anyone know if the 143 amp alternator will bolt on in a 1985 190e 2.3 without mod (other than replacing the pulley and rotating the rear housing)?

It should, assuming your 190E has a serpentine belt. You'll need to do electrical mods since the stock wire harness has blade connectors and the 143/150 units have post connectors. But, you'd want to increase the wire size anyway so I'm assuming you planned for that. I'd recommend 4ga cable from the alternator to the battery.

:)

143
 

It does have a serpentine belt, so I am going to give this solution a try.

This is actually the second alternator swap I'm doing on this car. I swapped out the original 65 amp alternator for a 120 amp Volvo alternator when the stock amp couldn't handle my stereo amplifiers. This required the shop (the car is in Peru) to modify the mouting bracket and install a slightly longer belt. I've never been happy with the modification, as the pulley is not perfectly true and in line with the rest of the pulleys and wheels that the belt winds around. This causes a lot of stress on the belt tensioner -- which I have had to replace twice after it snapped off the mounting bracket.

I'm going to ditch the Volvo amp, replace the modified alternator bracket with a new stock bracket, and install the 143 amp alternator.

Awesome! Let us know how it works out.

:cool:

You're an engineer, certain numbers are memorized during school, 746 w/hp, Pi, C, 3-4-5 triangle, etc. :)

Can you tell me more about the distriibution block?? Can the old one be rebuilt to work with the bigger alternator?? Or will I have to find one off another car??

You could use the stock distribution block but that will limit the size of the wire you can run from the alternator, limiting the effectiveness of the upgrade. If you read my post carefully, you'll see that I added an aftermarket distribution block in addition to the stock on, I didn't replace it.

:kid:

how difficult is it to change pulleys?

Pulley changes are usually easy if you have an impact wrench, although I was not able to remove my old pulley despite extreme efforts. I bought a new pulley (~$25) for my two diesel upgrades, and I have never had trouble removing the pulleys from the 143/150A units with an impact wrench.

:wacko:

Update
 

I just did another upgrade, this time I installed a 150A alternator into my 1993 300D (this was LONG overdue... wish I had done it sooner). For this installation, I kept the stock battery cables, battery terminals, and factory power distribution block all intact. I hadn't done this before - my previous installs used aftermarket items instead.

This method makes for an easier install (and cheaper, too). I used two 4-guage cables to simplify connection at the stock distribution block. It works perfectly. If you don't need to attach large cables to feed aftermarket stereo amplifiers, etc... I'd recommend duplicating this setup. I took extensive photos this time, and documented the creation of the custom cable. A few sample photos are shown below... the full batch of pictures are available at this URL:

http://www.w124performance.com/images/W124_stereo/alternator/

:euro:


http://www.w124performance.com/image...ble_4ga_01.jpg


http://www.w124performance.com/image...ble_4ga_07.jpg


http://www.w124performance.com/image...ble_4ga_12.jpg


http://www.w124performance.com/image...ble_4ga_20.jpg

Just installed the 143 Amp on 1989 300CE
 

Thanks for the mod information. I just installed a 143A alternator on my 1989 300CE and it works great. I can run my heater blower, defrost, headlights, stereo at idle no problem. I ended up two strands of 4ga wire 60" long with one strand 16ga as recommended. Using the stock distribution block was easy; I placed one 4ga wire on each of the two posts. The pulleys were easily switched using an impact wrench as previously mentioned.

Great mod, purchased the alternator on ebay for 115. Wire and terminals cost me $40 at a local stereo store. Took approx 3 hours of work to prepare then install, and I changed the serpentine belt as well.

Thanks again for the information!

This upgrade would sure be great on my w210. The defroster drops voltage. I think my stock alt is rated for 70 or so amps. WEEAAKK!

Hardcharger, glad to hear your upgrade went smoothly! :)

michakaveli, the same upgrade should work on your W210 also...

:balloon2:

followup
 

An old, old thread. Just wanted to give an update. I had my mechanic perform the 143a alternator "upgrade" to my '89 300CE about six or seven years ago now. Can't remember exactly because it has been working flawlessly since being done. No issues at all...absolutely none! Can't remember if the cable was replaced or not. I'd have to check the mechanic work order.

Same here. I've had the 150A upgrade on my cars for years now, with zero problems.

:scholar:

Will this work
 

I think I've found a 123 drop in upgrade.
Here's the background. Somehow, the bottom mounting bolt in my 83 300D-T broke but did not fall out. In changing belts, I found the problem but it had grown into a bigger issue. The broken bolt had vibrated around enough to make the alternator and the engine mounted bracket out of round and therefore hard to hold in alignment. It's still holding but I went to PNP for the 1/2 Labor Day sale.

I found an 84 300D-T with a good bracket and an alternator that didn't turn as freely as I thought it should (but I could use the parts to fix mine). I kept searching and found a recently rebuilt Bosch alternator in a 1984 500SEL. 137 amp with the same dual V belt pulley as mine and the donor 84. I bought it all (bracket and two alternators for $42.49 (including all fees and taxes). I've not installed it but I did do a test fit into the mounting bracket I pulled - exact fit. It measures 3/8" deeper so I may have to rotate the back to make it clear the AC hose, etc. Looks like the same pully but I'll take some better measurements before installation. Got to wait on some more free time to do the work. I did find that Eagle offers rebuilt alternators up to 150 amp for the 123's.

Any reasons not to proceed as long as I increase the wire sizes?
Any other recommendations?

I have been running a 150amp alternator in my 300TE thanks to Dave for about 3 months now.


Cranks out 13.4 volts with everything on, and stereo blaring.

Thanks!

I have a Saab 115amp alternator in my 83 CD with 4 large amps @330 watts RMS each and I have no trouble burning up my passengers hearing.

Will this alternator fit on a 190D?? Thanks

Yes. You may need to re-clock the alternator (depending on what donor you use), and you will need to swap pulleys (use the one on your original alternator). And of course upgade the wiring, etc. All of the serpentine-belt alternators will interchange through about 2001 model year... after that, they switched to a different 2-wire voltage regulator.

:chinese2:

"YES" :eek: I will be going for the upgrade Thanks gsxr

FWIW, I did the 150A swap on my 603 Diesel a while back, works fine. Also installed it on my 300SEL.

I am talking years ago.

I have had a 143 on my 87 300DT 5-speed since I built it three years ago. I upgraded the cable and am powering an amp and two veggie oil heaters and an electric fuel pump without any trouble. I am planning to upgrade the headlights at some point too.

Finally upgrades to 143 amp alternator. Ran a #2 ground to alternator bolt and 2 #6 to alternator output. and a # 10 to the for the small wire. All terminal ends are soldered on.

I can idle with headlights on high , fog lights on after-market driving lights on and my Fluke meter reads 13.98 volts. What an amazing upgrade.

So in upgrading my 88 300ce alternator there are three wires on the back of my stock alt and the new 110-120 amp e420 alt has a b+ and a D+. Where do the two larger of my stock wires go and where does the little wire go? Thanks.

:boat:

Just put in a 120A S320 alternator a few months ago. Night and day difference. With my stock 65A alternator, my headlights used to dim slightly after 3000rpm, and at redline they were very very dim. After shifting the lights would go back to full brightness. Not very confidence inspiring. :D

Thanks for the info. The stock 94 E429 alternator is rated at 60-110 amps and I got it for $50 shipped on ebay! Nice wheels on that 91 300e. They look like Porsche turbo wheels in that small pic.

They are actually 17" replicas of the wheels found on the "C58 Brabus"

http://lh4.ggpht.com/_xwMtgQOOLBY/Sr...%205.8%201.jpg

... not sure of the need for this step.
the alternator is attached to a solid aluminum bracket, bolted to the block, and there is a large copper braid connecting the block to the body of the car.
this would eliminate the possibility of a voltage drop from the battery to the block through the body I suppose...
certainly if charging issues are happening, adding an additional ground to the alt frame could help. as could cleaning all the existing connections, and brackets.
Hmmm...