I recently bought a very clean 91 420 SEL, dark grey over a light grey interior, as the 'good' car, a daily runabout for the wife mostly while I drive the 'work' car, a (coincidentally) 1991 also, a little stripper S-10. I hope to get 8 years or so out of the old gal. It's hard up here in the salty north.
Dark grey over a light grey interior, chrome factory rims, sunroof, 69k miles, factory service stamped until 55 or 56k (the one nearest that) then copies of receipts up to recently. The entire engine compartment is covered in what appears to be cosmoline. Right now I only have the one pic.
Although all the fluids I can check appear to be nice and fresh, it otherwise appears very original overall, so I'm giving it the old car onceover: belts hoses wires etc, lube everything, research research research. I'm also awaiting on a copy of 'Buying and Maintaining a 126 S-Class Mercedes'. This site in particular has been extremely helpful. I am wide open to comments and suggestions!
Its super interesting, seeing the difference between 'normal' cars and this beast. So far the shocks on the motor mounts are perhaps my favorite. The 90 degree hood is awesome too.
As I've been replacing parts I've been watching the differences between the new parts and the old ones and thought I'd comment on them, a way for a newbie to contribute In no particular order
The tstat. The new one is REIN CTI0019. It does not have the brass bits the old one has. Also, had I known what a pain it was to change I'd have bought OEM at least.
Main coolant hoses. I bought 'real' MB ones. Still, only one actually says Mercedes on it, and they don't seem to be quite as thick as the old ones.
Wires. I used UNITED MOTOR PRODUCTS 9805 - these are 'packard' wires and I've always considered them a premium set. However in this case they were a bit inferior to the existing wires. No spring clip around the bottom of the metal cups, and the boots on the cap end weren't quite as long. They were also a little bit thinner.
The Bosch 7905 plugs appeared very close to the old ones. The cap, rotor, and coil, BOSCH 03227, BOSCH 04177, and BOSCH 0221502433, all appeared to be exactly the same as original.
For the voltage regulator I originally bought AC Delco Professional E675A, then changed my mind and bought the Bosch 1197311028. When I pulled the original I compared all three. Interestingly, it was the Bosch that was redesigned, while the AC Delco appeared to be the same as the original. Which one is actually better? I have no idea. I put in the AC Delco as it seemed a little heavier duty.
And that's where I am now. I put a new radiator cap on and that immediately caused a radiator leak (of course!), so I'm about to install a NISSENS 62727A and will comment on it.
A note on the hose/tstat/belt install - having the radiator out made it 1000 times easier. I removed the fan too (and gave it a light sanding, the surface felt rough). This made such a big difference I feel it's probably worth pulling the rad and fan to do this job even if your radiator is OK.
Any thing else in particular I should be looking for / planning?