Installed a 143A alternator in my W124 (86-95 E-class) - with photos - Page 4 - PeachParts Mercedes-Benz Forum

gsxr · #46 07-08-2008, 05:24 PM

I left that terminal open on my setups also. I suspect it might be a connection for a condenser or capacitor, or something like that, on certain models? Anyway, how do you like it?

babymog · #47 07-08-2008, 07:04 PM

Big improvement.

Short trips with the A/C on would lead quickly to weak cranking, killing the (1y/o) battery with partial charging.

Now it cranks fast, and the blower speed doesn't change when I accelerate (inversely proportional / speeds up at a stop as the voltage drops).

I can't wait to drive at night ;~)

BTW, the old/removed alternator tested in spec.

Hit Man X · #48 07-08-2008, 07:23 PM

Sounds right that there's some resistor there, some of my alts have that. I just transfer it over.

For the 143-150A units, just two wires. I used a 2awg to the battery and the switched off the junction block.

compu_85 · #49 10-29-2008, 12:43 AM

Quote:

Originally Posted by babymog

Do you know what the W terminal is?

W is the stator output. (That's how the tach in my 91 Jetta TD was run)

-Jason

gsxr · #50 01-02-2009, 12:57 PM

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/

compress ignite · #51 01-02-2009, 06:30 PM

Dave,

Thanks!

[Professional Workmanship and Execution]

'Any reason to install larger AWG cables from Power Distribution Block to Consumers ? (Battery,Starter,Pre-Glow Relay,Etc.)

gsxr · #52 01-03-2009, 07:35 PM

Quote:

Originally Posted by compress ignite

'Any reason to install larger AWG cables from Power Distribution Block to Consumers ? (Battery,Starter,Pre-Glow Relay,Etc.)

I have thought about that myself. In the end I decided that for the stock electrical items (battery, starter, glow relay, etc)... the ROI is very low on upgrading any of the wiring. I wouldn't bother with this.

However if you are adding non-factory electrical loads (high-wattage headlight bulbs, large stereo amplifiers, heaters for WVO systems, etc)... those must be fed directly from the battery or distribution block, and properly fused for safety.

a2t · #53 01-03-2009, 10:28 PM

Another great thread to bookmark, many thanks!

How hard is it to replace the alternator in 87 300D?

My 87 has 283k on OEM alternator, so I was ready to replace it soon anyways. I will certainly upgrade when I replace. This will come in handy next time power is off for days and Im using the Benz as a house generator. Must of been why it was so slow to crank after idling 12 hrs last time.

On another note, I dont think Ive seen a car yet that puts out more than 13.5v at idle. Everything I drive (01 Escape, 92 Corrado SLC, 87 300D) idles at about 13.5 no acces, 13 w.acces. Although I had an 83 GTI with a bad internal reg and it idled at 15v, 16.5v at speed. Had to run EVERY accesory to keep in the high 14s. Turned the battery into a swollen grapefruit.

dieseldiehard · #54 01-03-2009, 10:51 PM

? you using the '87 300D to heat your house? What are you doing, stepping 12V up to 120AC with an inverter? I've heard extended periods of idling is not good, carbon builds up, etc. In a pinch I would do the same however, heat is important (electric blankets running off the Benz maybe not though.
GSXR has upgraded his '87 300D to higher amperage alternator, its all documented, just do a search. Swappin in the alternator is simple (if its the right one). The trick is making the cable shown in this thread, thanks to GSXR.
I attempted to use a 150A alternator but the pulley was slightly out of place and I shimmed it with a thick washer but still didn't like the fit so I went back to OE alternator. That will change next Spring though when I try to fit a second battery in the trunk and I'll have to be on the lookout for another alternator.

gsxr · #55 01-04-2009, 10:59 AM

DDH, as noted in this thread, you must swap the pulley. If you're installing on a 1987 300D, you must use the pulley from a 1987 300D (but WITHOUT the spacer that is present on the stock alternator!). If you use the old spacer on the big alternator, the pulley will be 1/8" too far forward, and the belt won't line up at all.

Proper setup is 150A alternator --> OM60x pulley -> locknut. NO spacer!! This makes everything align perfectly.

a2t, trust me, the 150A puts out over 14v at idle, like all good alternators should. When cold it's 14.5-14.6, when hot it's 14.0-14.2... even under load. Perfect.

a2t · #56 01-04-2009, 03:02 PM

Quote:

Originally Posted by dieseldiehard

? you using the '87 300D to heat your house? What are you doing, stepping 12V up to 120AC with an inverter? I've heard extended periods of idling is not good, carbon builds up, etc. In a pinch I would do the same however, heat is important (electric blankets running off the Benz maybe not though.

No not to heat the house but used inverter to run the fridge and the TV for 12 hours or so. Wish I took a pic of the old benz idling in driveway with hood propped and cables/extension cord coming off battery, getting pounded by 70mph wind and golf ball sized hail, all the while running on WVO. Sort of a man vs nature vs Exxon-Mobile situation

The only thing I noticed after 12 or so hours was it cranked slow, must not of been charging. This guy ran his 40 hours !

Powering my house with the MB

Thanks GSXR, yeah I'll swap in the 87 alt pulley minus the spacer, no problem. Just wondering how hard it is to actually R/R the alt. Does it just drop right out the bottom?

gsxr · #57 01-05-2009, 02:14 PM

The stock alternator puts out a max of about 40A at idle, and the voltage is probably low 13's. I'm sure it was doing very little, if anything, to charge the battery with extended idle time. The stock 70A alternator is very inadequate! Mercedes should have been embarassed to install those on 124's and 201's in the early 1990's (when much better 90-110A were easily available, and used on more expensive Mercedes models).

babymog · #58 01-05-2009, 02:46 PM

Two bolts and unplug, it'll drop right out. Takes as long to remove the belly pan.

Quote:

Originally Posted by a2t

Thanks GSXR, yeah I'll swap in the 87 alt pulley minus the spacer, no problem. Just wondering how hard it is to actually R/R the alt. Does it just drop right out the bottom?

gsxr · #59 01-05-2009, 03:14 PM

Don't forget to loosen the serpentine belt first, though.

I forget if the alternator can come out with the cooling fan still in place, but I always pull the fan+clutch to allow easier access to the two mounting bolts. But it's still a breeze... very simple swap.

Tip: Use an impact wrench to remove & install the pulley. It is very difficult otherwise.

babymog · #60 01-05-2009, 06:40 PM

Yes, cooling fan in place is not difficult. Good catch on the belt, ...