Thanks for the source! Copy / paste below for reference. This should probably be a sticky at the top of the "E500E For Sale" section of the forum...
"@ JNasty, like Toyota said, “You asked for it”! Here it is. Remember, this is unedited and unscholarly “off the top of my head” cut and pasted from a very long text message stream with a like-minded motor-head friend that was interested in one of these that was simply too cheap to be worth its asking price, if that makes any sense to you. To my observation of that, he asked “How bad can it be?”
!! NOTE TO ANYONE READING THIS!!
And most especially to anyone interested in this particular car!
Please note that much of what I’m talking about here as already been addressed on this car, so that has to be considered greatly in its favor!
Here goes, control C…
The body is fabulously well made. The top and bottom ends of the engine, and the differential are pretty bulletproof, except for occasional oil leaks. That’s a particularly good thing about that the diff, because it has its own gear ratio shared with no other model that uses that particular size of housing.
Sometime between 70 K and 150 K miles the transmission will require rebuild or replacement. Just about everything else attached to that drivetrain and body will at some point require expensive repairs to have a car that is enjoyable to drive. Many of these cars are at, or even way past that point now. Many of the third and fourth owners that they are currently in the hands of do not have the resources or the will to put them right. And to make matters worse, even though those owners often couldn’t produce the resources to maintain their cars properly, they did somehow manage to find the money to perform any number of aesthetically tasteless and mechanically detrimental “upgrades”. The most common of these being cartoon size wheels, incorrectly done “first gear take off” valve body modifications, yes, these cars have the usual for the era MB “three speed with underdrive” gearing, and people fight endlessly against it instead of just pulling the lever back on those occasions where they want to jump away from or towards(?) something, and the butchering of interior panels and wiring harnesses during the fitment of “entertainment systems”…
Here’s a list of most of the common things that I’ve seen wrong:
I’m going to attempt to start at the front bumper and work my way towards the rear:
Radiators crack and leak. Main heater hoses split. Early version thermostats fracture at the wax element and stick closed. These last few problems are usually hastened or preset for re-occurrence due to inoperative engine fan clutches. These are almost always under-diagnosed. Bolting a new one on doesn’t always make them work either. The vendor frequently manufacturing them maladjusted such that they did not engage until long after the auxiliary electric fans were screaming away in a futile effort to cool 5 liters of V8 and air conditioning stuffed into a space suitable for 3 liter straight six. Cooling system components and drivetrain elastomers cooked away while the temperature gauge hovered in the upper fourth of its travel. Extreme caution combined with experience, most of that experience bad, can adjust the fan clutches to actually work.
The power steering pump is also integral with the hydraulic pump for the rear suspension, 2 pumps on a common shaft. They develop leaks. They can be exchanged or resealed, but not inexpensively.
The power steering return and cooler hoses are subject to leak formation and they are a pain to replace. Fortunately, they aren’t too expensive.
The power steering gear box can leak at the bottom cover. These can be easily resealed.
Valve cover gaskets can leak into the spark plug bores.
There are little oil distribution pipes that carry oil across the cylinder heads supplying oil to the valve lifters. Later versions of these are plastic, and the end plugs blow out of them causing valve train noises. They are time consuming to replace, but at least they can be replaced with only the valve covers removed, so major disassembly is not required, and like I said, you’re going to have the valve covers off for a reseal anyway.
Distributor caps, distributor rotors, and the chronically under-diagnosed insulator plates between the cam shaft mounted distributor rotor drivers and the cylinder heads frequently revert to their constituent molecules, a process dramatically hastened by the aforementioned chronic hot running. These constituent molecules once liberated from the plastics do a very efficient job of conducting the ignition voltage away from the spark plugs. Note also that it’s twin coil and twin distributors so double your pleasure there.
The spark plug wire ends have internal RF suppression resistors that sometimes burn open. This causes extremely high voltage to form in the wires along with the misfiring. When this happens, one will usually see arcs in the wire bundles and / or near the conductive plastic caps that cover the distributor caps. This causes endless numbers of complete wire sets to be replaced, which is a massive PITA, as they cross the engine alternately from the two exhaust camshaft mounted distributors. And they are encased in order enforcing plastic channels, and this is all buried under the fuel injection components. Of course, many of the aftermarket replacement wire sets used are made of Fig-Newton filling hardened with Final-Net, so now it really does need plug wires, and there you are.
While we’re on the subject of ignition systems, the computer that manages all ignition system functions and fires the two coils sometimes fails, either completely dying or refusing to fire four cylinders. Their availability comes and goes, and for a number of years now the price has been almost seasonal, fluctuating between $1500-3800.00.
Ignition coils themselves occasionally fail, sometimes, but fortunately rarely taking out the aforementioned diamond encrusted ignition control module in the process.
During this era MB like many manufacturers, including airplane manufacturers(!) was experimenting with recyclable wire insulation materials. They were preparing for the ECE regulations taking effect in 1998(?) that effectively made the manufacturers 100% responsible for vehicle recycling. Some of these materials did not work so well, starting out on the journey to their recycled future right now in the present, while you’re trying to drive to work. Upper and lower engine wiring harnesses deteriorated and shorted. Pigtail wiring harnesses permanently connected to horridly expensive items like the drive by wire throttle actuator similarly deteriorated.
Brake pedal switches and transmission neutral switches frequently made the drive by wire throttle go limp. The transmission wiring harness that the neutral switch connects to is subject to water infiltration and corrosion. Those conditions are under-diagnosed, and the fault codes that the system produces usually lead one to mistakenly replace the fabulously expensive (and fabulously well made for that matter) electronic accelerator control unit.
The hydraulically damped motor mounts collapse and sometimes break. Excessive drivetrain vibration, especially at idle and when accelerating, and a weird under-damped front suspension sensation that feels just like bad front shock absorbers results. The purpose built, with internal rebound limiting spring(!) front struts are then sometimes replaced with vastly less expensive aftermarket “upgrades”. The car then has the benefit of even greater body roll in hard-driving combined with a brutal ride. Oh, and that weird under-damped Jell-O like sensation in the front of the body that prompted someone to replace the struts in the first place? It will still be there because it is caused by the defective motor mounts not “tuning” the mass of the engine from the chassis.
Air conditioner vacuum elements leak and cease to function. The most common fault that causes is inadequate AC cooling under heavy demand, combined with cooling of the windshield. This can produce a really interesting condition, especially if you consider terror really interesting: You can’t see through the windshield during the southern summer, especially at night, as the fog on the exterior of the windshield re-forms immediately following, and only about an inch behind the wipers! Even on high!
While we’re talking about air-conditioning, the evaporator core either has already been replaced or it is probably soon going to require replacement. Replacement requires removing pretty much everything forward of the front seats all the way to the firewall. Then the heater case needs to be disassembled and the evaporator replaced. Careful not to break anything inside that heater case! Many of the cool things like the folding plastic(!) hinges on some of the linkages are not available separately, and would pose quite a challenge to manufacture on your own.
Driveshaft center support bearings are starting to lose their resilience and create some vibrations. That’s not too hard to fix especially if it’s done during one of the times when the transmission and / or the differential are removed.
The brakes wear more frequently than on a number of cars, no big surprise there, but fortunately they don’t cost too much to replace.
Interior headliners disintegrate and sag annoyingly. They are no longer available from MB, but they can be tastefully repaired once they are removed from the vehicle.
If the factory radio and sound system are still intact (as I warned above, that is not likely), its components can be repaired inexpensively by the vendors. The vendors can even do a particularly nice modification that involves wiring in an auxiliary audio jack. People can then use their iPods or whatever device they choose to play their music.
In my opinion this is far preferable to tearing up your vehicle, not to mention then having to look at that Godzilla horror movie disco electronic display that now contaminates one of the most tasteful and functional instrument panels ever put in an automobile.
The rear suspension system has hydro-pneumatic self-leveling. If the rear springing seems hard and bouncy, the nitrogen filled diaphragm spheres need to be replaced. These are wear items. Count on doing it again in 4 to 7 years.
In a similar manner, the purpose built rear struts (also fitted with internal deflection limiting springs!) frequently develop an annoying metallic rattle that emanates from somewhere inside them. They cannot be practically disassembled or repaired. Not surprisingly they aren’t inexpensive.
Due to the wearing nitrogen spheres and rattling from the struts, the rear suspension can also be the unfortunate recipient of “upgrades” with the expected disappointing results. If the struts are simply leaking and the ride is hard replacing the spheres alone will usually restore the ride quality and eliminate the leaks. The leaks result from the hydraulic system essentially being solid fluid once the nitrogen his left the spheres. Imagine the lip seals on the strut pistons. With every bump they are subjected to some tremendous pressure spike immediately followed by a vacuum. As a result some oil gets by them.
The back window glass was a special laminated version with a fine wire heater, just like in the most expensive S-classes. They sometimes delaminate and fog internally. Fortunately they can be replaced with the conventional single pane 124 back glass, and no one will notice the now visible defroster grid. Of course if you don’t mind paying for it, you can always replace it with the original laminated version, despite its being far more expensive and failure prone.
They guzzle gas. No I’m serious; you’ll be shocked how much gas one of these things goes through even if you’re not pushing it hard.
Even if all of the things I mentioned are perfect, you will still need to have $ 5k. or so lying around to throw at it over the couple of years or so. I am no doubt forgetting a number of things…"