MYSTERY SOLVED!

I took the car out this morning & experienced the same thing I have been. Took 3 times to start, then bucked & sputtered for about 30 seconds before smoothing out and running fine. A few hours later I was going somewhere else and everything was absolutely DEAD! No dash warning lights, no buzzers, no headlights, no crank, nothing.

I used a multimeter to check the battery voltage. 12.88 volts, then I hooked one end of a jumper cable to the negative side of the battery and the other to the body. Still dead. Then I spotted the smaller wire that is nutted to a stud on the positive battery cable connector. Somehow I never noticed it before. The nut was not even finger tight! I tightened it and everything came back to life! Started on the first try, idled smoothly right away.

I traced the wire to where it terminated in a junction block on the inner fender, popped off the cap and saw that there was a little corrosion on the 2 posts and nuts.

Anyway, I took it all apart, wire brushed all the corrosion off, bought new stainless steel nuts, washers and lock washers, coated everything with silicone dielectric grease and put it all back together.

It now starts first time everytime, and idles perfectly right from the get go.

Life is good again!

Another thing that was apperently related was something odd in the climate control. It had started putting out cool air from the side vents when I needed heat. Now the side vents are warm again.

Hard to believe so much trouble from a loose 6mm nut.

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2000 Mercedes S500
1990 Mercedes 560SEL
1970 Triumph Spitfire