PeachParts Mercedes-Benz Forum - View Single Post - DIY

Alec300SD · #2 01-12-2015, 12:03 PM

Transferring parts from old alternator to new alternator: First remove the nut and lock washer holding the pulley, keyed shim and alternator cooling fan to the alternator shaft. I used the alternator mounting bolt wedged between the fins of the fan to immobilize the shaft and a 22 mm box end wrench to loosen the bolt. It was a little hard to remove the pulley. I did not have my puller readily available so I just slowly drove off the pulley by wedging a bolt end between the housing and the fan and tapping the bolt a couple of times, repositioning the bolt and tapping again until I drove it off the shaft. I transferred the pulley, keyed shim and fan to the new alternator. I used the new wave washer and nut that was supplied. The new alternator shaft has a hex head recess so it was very easy to tighten the nut held by the box end wrench and the shaft held by a hex head socket. The next part to remove is the condenser, which reduces radio interference from the alternator (it is the black plastic box with the spade connector at 9 o’clock and grounding screw at 6 o’clock on the top picture of the back of the old alternator). I connected the condenser to the spade connector at 7 o’clock and mounted the grounding screw at the tapped hole at about 5 o’clock on the bottom picture of the back of the new alternator.

Installing new alternator: I oriented the old alternator adjusting bracket on top of the new alternator and from underneath the car, re-positioned the alternator into the bracket which is bolted to the block. I installed the lower alternator mounting bolt first and then from above installed the upper bolt (but only finger tight). I installed the used belts, adjusted the belt tension with the 13 mm adjusting nut and then tightened the three 17 mm bolts (two on the back of the adjusting bracket and the lower one on the alternator bracket).

Wiring to the new alternator: The existing harness was modified. The spade connectors of the two red wires were trimmed away and new heavy duty ring lug connectors were crimped onto the two red wires (8 gauge). The thin blue exciter wire was not modified except for freeing it from the old black plastic connector plug. (The frayed sensor wire for the thermostat temperature sender was repaired with a butt splice connector). The two red wires connect to the large unmarked post (usually called B+) on the new alternator and the thin blue wire connects the spade connector on the small post of the D+ terminal. People on the forum have expressed concern over current carrying ability of the stock wiring, so I added additional wiring. I purchased 2 feet of red and black 6 gauge marine grade tinned copper battery cable wire and 6 gauge lug connectors. I installed one end of the extra black cable to the alternator housing (under the condenser mounting screw) and the other end to the negative battery cable where it attaches at the body. I installed the extra red power cable to the large post (B+) and the other end to the positive terminal in the junction box beneath the battery. All the connection ends were treated with electric contact cleaner and then electric contact conditioner.