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Mercedes 300D Suggestions



  • Mine was a 1975. I do not specifically recall the number type. It was definitely a fixerupper,but after having it painted, new mb-tex seat covers , and new michelin radials, along with a muffler, the wife of one of my business partners said it was as nice and rode as comfotably as a friend's Rolls Royce. At that, I knew I would always own a Mercedes Benz. :shades:
  • Mr_ShiftrightMr_Shiftright Sonoma, CaliforniaPosts: 57,595
    Until the Germans got ahold of them, it wasn't hard to be more reliable than a Rolls Royce.

    Probably they wouldn't have been so complimentary had you fixed up a 300D, since they are quire comfortable but rather noisy and slow. A UPS truck comes to mind rather than a Rolls. But even the old diesels have that "rock steady" feel on the road that we've come to appreciate in a Benz and, once squared away or restored, a very credible level of reliability.

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  • fintailfintail Posts: 41,923
    You've got a W114 then, also called a "squareline" or a "strich acht". What color is it?

    I have to believe there was some kind of strategy back in the day to make the cars age well, so even used cars would lure people into the brand.
  • the color is ,I call it butterscotch, about the color of those Weler hard candies that you cannot stop eating with only one piece. My mechanic shop owner had a '72 4 dr also. He tried to bargain for the european headlight assemblies. no, no, no I said, those headlightss are a part of the package and the add to the appeal and character of the Benz. :shades:
  • fintailfintail Posts: 41,923
    Those lights are pretty are wise to keep them. On those cars, it makes them look better...only on W111/108 cars do the US spec lights look decent.
  • wwestwwest Posts: 10,706
    edited August 2010
    Driving north out of Yakima Sunday morning just after crossing the Harold Redmond bridge I noticed a car about 100 yards behind me appear to EXPLODE, big cloud of white smoke, steam(??). Driver seemed to take no notice as the car continued to follow us for miles, 70 MPH, trailing a cloud of smoke/steam all the way.

    I first suspected it to be oil or steam but with it seemingly driving well I decided it could not be and therefore must be a "blown" diesel engine. As we started down the final cut, incline into Ellensburg, the smoke/steam stopped and the car accelerated downhill and passed us.

    I was then able to ID it as a fairly new Mercedes-Benz Turbo-Diesel 4 door sedan..

    Once it passed us our car windshield got quickly coated with a fine mist of.....smelled like kerosense....??

    The last we saw the car she took the turn to eastbound I90.

    Wonder how far she got...?
  • fintailfintail Posts: 41,923
    Was it badged "turbo diesel"? IIRC that badge hasn't existed since the W210 300D of 1998-99.

    Maybe some of greasel or other homebrew diesel conversion gone wrong? Or maybe some kind of head gasket failure.
  • wwestwwest Posts: 10,706
    Yes, top passenger side of the trunk lid was labelled "turbodiesel"

    Those here at the office are guessing "holed" piston.
  • fintailfintail Posts: 41,923
    Could be it. Big clouds of anything usually mean some kind of catastrophe.
  • I've got a problem with something running and draining my battery while my ignition switch is off. It was a complete mystery until last weekend when I opened the hood and heard a rapid ticking sound that emanates from what appears to be the vacuum distributor, since it has a load of vacuum tubes running to or from it. I've got a manual, but can't seem to find out what the thing is, let alone why it's running.
    My tendency is to jump to conclusions and it's cost me in uneccesary parts, so I'm looking for advice before buying an ignition switch. Thanks in advance.
  • Okay, I'm back. I'm now wondering if the starter lockout/backup light switch might be defective since I've been told that my backup lights don't work in addition to the car not starting in Park. Is this switch activated by something internal in the transmission or by something external in the linkage?
  • dotish.... this problem is one I am not familiar with, however, if I were faced with the situation I would make sure the key was not in the ignition when you open the hood as , as you said the battery goes dead and that ticking could represent the battery's last gasp so to speak because of the key alarm, open door alarm or open trunk alarm( buzzers and lights). With that cleared uo, next perhaps the radio is not operated by the key, and again the battery's last gasp. Third, if you boost the car to start it, when you turn it off, be sure it is either dark outside or park the car in the garage, turn motor off, close garage door, turn off garage lights and see if there is any light inside or outside of the car, that would represent a closed circuit to some light source that should be open as the ignition switch is off, doors and trunk closed, and light switch off. Check your cigarette lighters and ash tray lights, glove box lights, switches for rear window defroster, emergency brake light, vanity mirror lights, seat warmer light. Make sure top of battery is clean and no corrison at terminals. Also, the disk brake sensing light may be defective or loose and draining the system. Let me know if this helps and happy hunting. benzsilver :shades:
  • burdawgburdawg Posts: 1,524
    That "vacuum distributor" sounds like the servo valve to me, which is part of the climate control. It's also is electrical, so it could be the problem...............
    Does it have a large block of vacuum lines, electrical connectors, and coolant hoses going into the bottom? If so, it's the servo valve.
    The way I have always trouble-shot electrical drain issues is to disconnect the battery and put an ohm meter across the battery cables. Disconnect any lights, etc that could be activated (such as an underhood light) and then see what the resistance is across the cables. It should be very high. If not, then start disconnecting circuits by removing fuses until you find one that causes a big change. That will at least point you in the right direction. Some fuses are in line and may be more difficult to find. A good wiring diagram helps immensely.
  • Thanks for your reply. Yes, it's definitely the servo valve and it's definitely what's ticking when the battery is connected and nothing's turned on, including the ignition. If all that the servo does is related to climate control, I'll just disconnect it, since nothing except the defroster works anyway and I'm not going to need that any time soon in Texas.
    Thanks for the battery drain troubleshooting tips.
  • my 84 turbo deisel benz runs fine but wont go forward or backwards-It is an automatic.what could be the problem.It stopped moving after i shifted it in reverse after going forward without completely stopping
  • Any thoughts on how best to find a potential new owner (preferably in Bethesda, MD) of a classic '84 300D in need of some fix-ups?
  • Mr_ShiftrightMr_Shiftright Sonoma, CaliforniaPosts: 57,595
    Craigslist is really the best venue for this type of car. You want dreamers---big dreamers.

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  • benzsilverbenzsilver Posts: 21
    edited January 2011
    '84 cdt won't stop running when key is turned off! Help
  • Mr_ShiftrightMr_Shiftright Sonoma, CaliforniaPosts: 57,595
    edited January 2011
    It sounds like you have a defective vacuum shut-off valve for the fuel. This is located at the left rear of your engine (driver's side is left).


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  • Mr Shiftright: Thank you for your response. While checking the location of the shut-off valve, I have discovered a black vacuum line that goes thru the fire wall along with two yellow lines a green line, two gold blue strippped lines and another line. The goldblue stripped lines are connected to the ignition switch, the yellow lines go tward the defroster ducts, the green toward the a/c system and the other line somewhere else. these are all connected to something; however the black line is not connected to anything under the dash inside the car. the other end is connected to the y- connector that connects to the big line that goes to the booster and the business that sits on top of the rocker arm cover. I have looked for vacuun diagrams, however, none that I have seen so far illustrate the line that I am seeking a connection point. My vehicle is a "84 300 CDT. I have removed the lower dash panel and instrument cluster to be able to see the area better. I would appreciate your help and info regarding this quest. benzsilver and thank you again :cry:
  • Mr_ShiftrightMr_Shiftright Sonoma, CaliforniaPosts: 57,595
    I don't have such a diagram either. Best thing I always suggest with loose vacuum lines is to extend them as far as they will reach in a 360 circle until it meets up with a connector that it can reach.

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  • Glad to see Mercedes-Benz recognizing the work of Mercedes Motoring out of Los Angeles. They do some incredible work. I've followed them for years and their restorations only get better. Check out this short documentary on
  • Mr_ShiftrightMr_Shiftright Sonoma, CaliforniaPosts: 57,595
    Too bad the people making the video were more interested in their cameras and the music than in actual content. :mad:

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  • Hi Everyone,

    I'm thinking of selling my 81 - 300D non turbo sedan with automatic trans. I do not want to mis represent the car so would you please comment on my following statement about the transmission.

    Bought it in Houston 4.5 years ago and have been using it down here in Cuernavaca, Mexico ever since and it stills runs great at 220,051 miles, which I believe to be accurate.

    I noticed when I bought it that it ran up higher rpm's before shifting than I was accustomed to. A non related mechanic of vintage Mercedes' told me it was designed that way to keep the small diesel at high rpm's when climbing hills or steep mountains.

    I thought it made sense and I went back and bought it. But I did think it strange, and still do, that it would not shift earlier without a load on it.

    My 79 300 SL turbo., which i believe had a little more powerful 5- cyl. engine always shifted like the many american gas cars I've owned over a lifetime.

    The little 5 banger has faithfully climbed Mexico's highest mountains and has made countless trips between South Mexico and Texas and Louisiana. The trans. shifts the same today as when I bought it. A different Vintage MBZ mechanic in Dallas told me the same thing plus gave me a tip to release the excelerater momentarily when I wanted it to shift earlier and that has worked fine over these 4.5 years.

    Can any of you pros. out there tell me the correct story of this particular automatic tranny?


    PS: I'm fairly certain the Trans. is operated by vacuum from a vacuum pump attached to the engine.
  • Mr_ShiftrightMr_Shiftright Sonoma, CaliforniaPosts: 57,595
    Sounds pretty normal to me. You might check the vacuum lines that go to the vacuum modulator---or check the vacuum lines in general. If you have any kind of vacuum leak, this will affect how the transmission shifts.

    One tip off of a large vacuum leak would be that you can shut the engine off with the key sometimes.

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  • Thanks for your opinion Mr. Shiftright.

    Mickey Patin
  • Mr_ShiftrightMr_Shiftright Sonoma, CaliforniaPosts: 57,595
    By all means check the small vacuum lines and junction blocks that sit near the top/back of the engine on the driver's side.

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  • dotishdotish Posts: 20
    Hi, I've just purchased a 1985 300D turbo that runs well, but shifts with a jolt into 2nd gear. Can anyone suggest what the problem might be? Vacuum leak?
  • Mr_ShiftrightMr_Shiftright Sonoma, CaliforniaPosts: 57,595
    Sounds just like a 300D to me! :P If it was a vacuum leak, it probably wouldn't shift at all.

    They shift hard as a rule. Of course, we can't tell what you mean by "hard"---compared to modern transmissions or compared to other 300Ds?

    These are wonderful cars, but cars have come a long way since 1985, and now transmissions are electronically controlled to the max.

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