My 86 560SEL w/ 64K miles was running smooth as silk. Was sitting or a few days. Went out to drive it, started it up and it sounded terrible. Made loud knocking sounds but ran smooth, oil pressure gauge all the way up at 3 bars. I turned it off and now it won't even turn over!! Turn the key, everything lights up, turn key to start and just a hear a clunk. I've had a little trouble with the neutral safety switch, but could always jiggle the shifter and get it to start.

I'm worried the engine locked up from the terrible clunking sounds when I started it before.

Haven't gotten it to a mechanic yet. Obviously will need towed.

How could an engine that was so smooth and quiet just all of a sudden make such knocking sounds?

Could it be something simple or should prepare for the worst?

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R Martin
Dallas, TX (Addison)

86 560SEL, 128K