I am writing this review as a mechanic that has had the chance to work on a Mercedes for the first time.
Faults- the car had several faults, but several weren't the fault of the car, it was sitting for 1 year, outside, without fuel stabilizer, so the fuel system needed some work (sprang to life easily tho)
I'll stick to the things that wore out or failed due to time.
Power steering gearbox, leaks like its not even in the line. Pumps out fluid as fast as it can get in there. Fault- a bad seal (or 2) main one being the steering shaft input seal.
Water pump- wobbles a little and weeps... worn out.
Chrome wheels- chrome is peeling with no apparent damage to the wheel. Chrome plating failed.
Paint- the clear coat is GONE.. what little is left is peeling off rapidly.
ABS- a few pieces of the ABS system have failed such as the brake wear sensors (consumable part anyway)
AC Blower fan. These things give up a little quick- this one is more beat up than I would expect any motor to be able to do to its self. It has been replaced before as well.
Vinyl is peeling off panels.
Wires that power the windows break at the door hinges due to too tight a wire harnes, it makes them kink and eventually break.
Dash- it lost a ground or something, a couple of the gauges act funny= bouncing around etc.
Tail lights- the plastic becomes brittle and lights fall out/contacts aren't made.
One headlight wiper doesn't work.
Vinyl seats- yea you'd think leather, but not on the bolsters.. is cracked.
A couple electronic gremlins had to be knocked out. It has an over voltage protection circuit. the relay went bad, as did the headlight and fuel pump relay. 2 of the window relays have junk yard markings on them, but they may have been replaced to try to fix the intermittent windows caused by broken wires.
As stated, I am a mechanic. I received this car when a friend of mine moved and the car wouldn't. I paid for the tow and he signed the title to me. It had been sitting for a year (since the ac blower failed) and the fuel pump siezed. Both my wife and I drive a two door car so we thougth this would be a good "go to the beach/mall" type family car, so I've been going through it with a fine tooth comb to make sure its safe to put the children in.
I marked the 7 on performance as it does have more of a "day at the lake" feel to it. it doesn't corner or accelerate like a modern car. It's a classic.
I marked it a 5 on the running costs. If you have to bring it to mercedes- expect a 200 dollar per hour or more diagnosis charge and a similar labor rate. THey also charge through the roof for parts. Junk yards will do you great for parts. If your part failed it was likely a fluke. Nothing seems to "just fail" on a mercedes of this vintage. Used parts are great.
Having worked on Cadillacs of similar vintage I was VERY suprised to find that almost every accessory worked. Ones that didn't were easily repaired without needing to order parts, usually a matter of hooking up something the previous tinkering owner detatched or just stuck vacumm actuators. Everything works, but the auto antenna. Which may be due to the aftermarket stereo.
The car is completely over engineered. They thought of everything. All the switches, wire harnesses, motors, engine.. all are made with a quality of parts you don't even see on toyotas. Even after 20 years, they come apart without breaking and work fine. It's a shame these cars have nil value. They really will last for ever and still look fairly contemporary for approaching classic ages.
I was very suprised also at how smoothly the engine ran (considering time it sat with bad gas and water in it). It really gets up and goes, for an 86 low end luxury car. Its quiet and operates smoothly. Good oil pressure cools fine.
When I changed the tranny filter, I found a coupple small fragments of clutch, but it still works great with almost 200k miles on it.
Where the car fails is the vinyl pieces. The carpet is nice, the seats are still good, and would be better if they didn't get sun baked in california and hawaii for 20 years. Vinyl bolsters have cracked on drivers side. The vinyl on the trim though has failed. It uses a foam backed plastic sheet that falls apart like old headliners do. Once the foam fails, the edges peel up, and I haven't found a trim adhesive that will stick to this plastic yet.
The paint failed, was repainted, and failed again. THe clear coat was junk I guess, possibly bad maintenance. Even though the paint failed, and it's been a costal car its whole life, the only place that rust got to it is where some birds took advantage of the missing clear coat and disolved the paint with their feces. Of course on door edges where paint was chipped there is surface rust, but it doesn't spread like a japanese car would.
The parts on this car are painted everywhere. THey paint the inside of the fenders the inside of the doors the back sides of support pillars everything. You might think that's normal, but next time you climb under your car, check above the tranny... you won't find paint they just trust the body coating to save it.
Mechanical fuel injection. Probably the reason this car is still running.. well 2 reasons. It's engine could carry probably 3 times more horsepower. the engine block is large and iron with relatively small bore for the size of the block. And the second- mechanical fuel injection. If this car had a 1986 electronic fuel injection system, it would be long since burned up and expensive to repair. Instead mercedes went with a mechanical fuel injector. It will run even if the engine control units fail.