My alternator/charging system has been on the fritz on the 300 D. The local dealer coincidentally sent a free electrical system check coupon. I took it over there and they quoted $480 to put a rebuilt alternator in. I ask on the price of a rebuild unit from MB. Yeah I know they are on fast lane for $140 or whatever. Anyway I took the one from MB for $200 (12 month unlimited mile warantee).

I took mine out on Tuesday and got the new one and put it in yesterday late and in the artificial light. I had not problem. Everything was relatively easy. I buttoned up the air intake tube and reconnected the battery. Went out for a short test them realized I forgot to tighten the adjuster bolt to secure the belt tension.

Went back home and got my wrench and at the last turn of the bolt there was an arc. I shorted across the bolt and something on the alternator. The lesson, don't forget to disconnect the battery no matter what you are doing under the hood.

I put my voltmeter back on after that and it seems to be ok but I was and still am very nervous about it. What is the most likely thing I may have done to the alternator. I looked under the hood with a fashlight this morning and didn't see any meltdown.

Thanks for any thoughts on this.

Cheers.

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Tom Engel
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83 240 230K Manual (8/2003)
83 300D 265K (3/2004)
Just a Driver!

Most likely, you shorted the alternator's output lug to the wrench. That wire goes directly to the battery positive terminal. If the wire isn't fried, you should be OK. The alternator shouldn't have been affected, all the high current flow would have been outside the alt.

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Norm in NJ
Next oil change at 230,000miles