Date registered: May 2016
Vehicle: 2000 S430, 2003 S430, 2003 S600 TT, and 2005 E320 CDI
Mentioned: 169 Post(s)
Quoted: 962 Post(s)
1.) Sounds like your spark plugs and wires are fine, given that the engine's running more smoothly now. Probably either oxidation or, more likely, oil on the contacts. May be time to replace the valve cover gasket; they start hardening and losing their pliability at about this age. Doesn't hurt to do the plugs, but you may be able to just clean 'em with some brake parts cleaner and Scotchgard and keep steppin'.
2.) SRS-type stuff, get that car on an SDS (STAR Diagnostic System) and find out what's actually wrong. The project 2000 S500 had an SRS light, too. Turned out to be a broken (due to age and use) passenger seat SRS sensor (yep, I've got SDS).
3.) You deactivate it with SDS. I did it with my cars.
4.) Got me there. SDS will allow you to do actuations to help you narrow down where the fault is.
6.) There is a way to make your own switch nubs. However, I would just pull those nubs off of a junker car if you can.
7.) Normally I'd say someone put the wrong coolant in if I see green in there. However, if it's not the bright "fluorescent green", then it is actually possible that the coolant is correct. The spec for our cars calls for either G-05 or G-48 coolant; the original spec is G-05. It's similar to how 236.10 transmission fluid is the original spec for the 722.6 five-speed transmission, though the later 236.14 (developed for the 7-speeds) is also correct. The G-05 is typically yellow/amber, and the G-48 (from Mercedes-Benz) is blue. If someone already had G-05 in the cooling system, and then filled up with some G-48, you'd get a sort of forest green, darker than the Prestone "fluorescent green" color. That said, any "new-to-me" car will get its cooling system properly flushed with distilled water, followed by a 50/50 mix of either G-05 or G-48, just so I'm sure it's done right.
Be sure that your new coolant recovery tank is a Genuine-MB! The Behr "OE" ones are now made in China. The Genuine-MB ones are made in Italy, where Brembo brakes are also made.
2000 S430 (Dad's car, used for special occasions)
2000 S500 (wife's DD: my first W220 project car)
2003 S600 ("sex on wheels"--second w220 project car)
2003 S430 (one of two current DD's--third W220 project car)
2005 E320 CDI (the other current DD--first W211 project car)