PeachParts Mercedes-Benz Forum - View Single Post - Installed a 143A alternator in my W124 (86-95E-class)

Jeremy5848 · #70 03-28-2013, 12:52 PM

I just installed a 150 Amp alternator in my 1995 E300 (W124, OM606NA), replacing a 115 Amp alternator installed last year, replacing the OEM 90 Amp alternator. The 150 Amp unit was one of several offered for sale on eBay in early 2013, apparently scratch-and-dent specials, and originally designed for ML-class Mercedes in the 1999-2002 era.

The 90 Amp alternator should be very similar to the 75 Amp unit that came standard in early 124s and 201s (all engines with serpentine belts). It looks like there's enough room on most engines for the larger alternators. Remember to swap pulleys and upgrade wiring.

I don't have a bunch of extra loads in the car but it's nice to see how well the big alternator charges, even during afterglow. With everything in the car turned on, the system voltage stays above 14 Volts even at idle. The "fear factor" of the big alternator should keep the battery charged even without running the engine!

The new alternator is a tight fit on the 606 engine because of the nearby pipes bringing coolant to the oil pan-mounted heat exchanger. (The same engine in the 1996-97 W210 chassis puts the heat exchanger on the other side.) There is only 1/4 inch space between the pipes and the alternator but it's enough. I added a second cable to handle the extra current, a length of 8-gauge "Monster"-brand audio power cable rescued from the local auto junkyard.

Following is a comparison of the 90A, 115A, and 150A alternators. This may help someone who has yet to upgrade.

Source and part number
1. 90A 1995 E300, original, M-B #009-154-30-02
2. 115A (from a 1994 E420), M-B #010-154-06-02
3. 150A eBay, $75, new, M-B #010-154-83-02, intended for ML-430 and similar models

Weight
1. 90A 12-1/4 lbs
2. 115A 15-1/2 lbs
3. 150A 16-1/4 lbs

Pulleys
1. 90A Diesel 55 mm
2. 115A E420 44mm
3, 150A ML350 50mm
The pulley on diesel I-6 models is ~1/4" taller than on gasoline V-8 models. I don't know if the difference is due to the configuration of the block or the type of ignition.

Regulators (Bosch)
1. 90A 1-197-311-213 (looks old, made in Great Britain)
2. 115A 1-197-311-242 (looks newer, made in India)
3. 150A 1-197-311-213 (India)

Anyone know the difference, if any, between -213 and -242?

Jeremy

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Photos

The 115 and 150 Amp units are similar; the 90 Amp is tiny in comparison. Note that the Diesel pulley is on the 115 Amp alternator in these pictures.