Corrosion where wire joins distributor cap.
 

Hi all

I'm hoping someone has an idea as to what caused some serious corrosion in the distributor cap of my 87 560SL

This isn't inside the cap where you would expect to see it. Its where one of the plug wires plugs into the cap.

I was looking into what had caused a fowled plug and found a heavy white powdery corrosion in one of the holes where the plug wire connects. It was so extreme that there was very little juce going down the wire to the plug. The other seven where shiney as new.
After sanding and scraping it all off all is well.

My question is was this caused by a resistance problem with that plug wire or just some corrosion the just happened to occur on one connectin.

Very curious
Thanks in advance
Barrie

White powder corrosion deposits suggests aluminum oxide. I'm not familiar with your car's design, but are the terminals made from aluminum? It's easy to check... use a magnet.

The connection may have been loose. This would have caused arcing which, in turn, would have burned the metal. The other connections were tight, which would explain why it happened to only one terminal.

Clean the area as best you can so you get metal-to-metal and you should be okay.