Buying and Maintaining a Car
Mercedes 240D

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By Smartaz
September 26, 2001

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I have heard a few times about how reliable the Mercedes diesels are, so when I got ready for a car I bought a 240D. They are in fact reliable, if they still run. That is to say, they are either absolutely reliable or they don't run at all. But I get ahead of my story.

The 240D is famous for longevity, which is not exactly the same as reliability. It is mentioned in the Guinness Book of World Records that it is the longest lasting model, often going 300K to 400K miles with no major repairs. (They don't speak of minor repairs -- more about that in a minute.) Another big plus for the Mercedes name is that it is somewhat more likely to have been owned by people who could afford to do regular maintenance on it.

One thing about the Mercedes is that feeling of elegance. Just riding around behind that hood ornament is a big boost for one's ego. It gives me delusions of adequacy. It makes a person feel safe just knowing that the car has been designed by the best. There is almost no difference in ride or handling, whether at 50 MPH or 100. I also appreciate that the car will drive at any speed I want without surreptitiously increasing or decreasing it. Most cars I have driven were quite unwilling to go 25 mph -- they only wanted to go 40 or faster. That is very annoying in residential areas where they have signs saying, "CAUTION! SLOW CHILDREN!"

But there is a price for the elegance, reliability, and convenience. You may have no major repairs (major repair = junk the car), but there certainly are some minor repairs that will knock your wallet for a loop. When I bought my car, the AC fan didn't run. I drove it to a shop and told the mechanic, "It's gotta run!" Two and a half weeks and $880 later they gave it back. It seems that you don't replace parts in a Mercedes, you replace modules. And it might take some time to figure out which part is bad and what module contains it.

So when I got it back I took it for a spin. About a half mile from home it died. "Hmm," I said, "Sounds like the fuel pump quit pumping." Tow bill, diagnosis, new pump, etc, came to $615 and took two weeks to fix. So I've owned this car for 5 weeks, put $1500 into repairs, and I've only driven it about four times. I am starting to wonder what I have gotten into.

A diesel is not like a normal car. It takes a bit of training just to get it started. It doesn't have spark plugs, it has glow plugs. Those are light bulbs without glass, made to withstand the fire in the engine. To start the car you turn on the glow plugs and wait until they get hot. This takes about 10 seconds in summer, up to a minute in winter. Then you can crank the engine, and when it starts you release the knob and the current to the glow plugs is shut off.

So I started it up and headed for the store. At the end of the block I noticed the glow plug indicator was still shining, and rather brightly. But then it went out, so I figured it was ok and forgot about it. Next morning the indicator wouldn't come on at all, and the engine wouldn't start at all. It turns out that the knob has gotten old and no longer springs back to the normal position when I release it, meaning that the current is on all the time, meaning that a glow plug burns out. Glow plugs cost $28. Fortunately I could replace it myself so I didn't need to pay for another tow bill and labor charge.

Next morning, same thing. Same plug burned out again, after just one use. I rode my bike to the Mercedes shop and asked the guy if he knew any reason why that might have happened. He passed the question to a repair supervisor. (One nice thing about Mercedes is you get courteous service, even if you ride in on a bicycle!) The super said yes, in a car of that age it's likely that some carbon has built up around the glow plug and shorted it to the block, burning it out. They had a special tool for boring the carbon out. Of course that meant an hour's labor to bore all four of them. I guessed a couple hundred bucks for the job.

I was then escorted to a service adviser who gave me his business card (It's a class act all around!), checked with the super on labor time, and advised me the job would cost "a couple hundred bucks." I bored the hole myself with a screwdriver, checked for a short, and put it together. It works fine, except that I have to remember to push the knob in after starting, instead of just releasing it to spring back on its own. Maybe some day when it gets cool I'll pull that starter switch and try to clean it. But certainly not until it gets cool. The only thing anybody wants to do in the summer here is go someplace else.

So I took it out today and drove it about fifty miles. Even being 26 years old, the interior is still in great shape, it still rides like a quality vehicle, the engine runs smoothly, and everything in it works except that pesky starter switch. The engine compartment has a little sludge from the inevitable oil spills, but none from leaks. I will wash it out some day so I don't have to get my hands dirty when I poke around in there. But not until the weather gets cool.


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