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Mercedes 300D Suggestions



  • fusefuse Posts: 3
    As I said in a previous post, I've got the same problem of my '76 300D not shutting off.
    I'm getting tired of opening the hood and pushing the emergency shut off every time, so any help from any of you out there would be greatly appreciated!
  • Mr_ShiftrightMr_Shiftright Sonoma, CaliforniaPosts: 57,604
    It's a vacuum problem. Exhaust shouldn't have anything to do with it. Or the vacuum - operated device that shuts off the fuel is defective. This is also why the door locks don't work. You have a vacuum leak somewhere.

    RE: Restaurant Oils: --Can you tell us briefly how you solved the filtering and heating of your waste oil? Did you buy a kit from Greasel or some such?

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  • amonra22amonra22 Posts: 11
    the 300d turbo is having the same pulsating problems i was having a few weeks ago. I bought and used the bg k44 injector cleaner but it had no noticeable effect. you said in an earlier posting that i should check the waste gate and the hoses to the turbo. also how can i tell if the pulsating while at highway speed (and only at highway speed) could be the fuel injector or the fuel pump. and if so why would the loss of power only happen while on the freeway? if it was the injector or the pump wouldn't it happen all the time? thanks for your help and advice in advance.
  • amonra22amonra22 Posts: 11
    changed the fuel level sending unit, (new) reserve light went out, and fuel level on dash is fine. thanks for your info.
  • Mr_ShiftrightMr_Shiftright Sonoma, CaliforniaPosts: 57,604
    The injection pump is constructed to provide different fuel deliveries under different conditions of load and speed, so it's very possible for it to behave sometimes and not others.

    I really don't know the answer to your question. I'm not even sure what you mean by pulsating exactly. If you have (and keep) even pressure on the pedal, does the engine slow down/speed up/slow down/speed up ....or ....???

    I still think you should also disable your cruise control for the moment while testing.

    Your injectors could just be worn out---they do wear you know. Maybe if all else fails you can have them pulled and tested--but you need special equipment for that.

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  • dyates773dyates773 Posts: 24
    If your 300D has an EGR valve it's worth checking. EGR valves are two way acting. They open by vacuum control or by high exhaust pressure. If the spring mechanism is weak, broken, etc., at highway speeds the valve can leak by causing surging or loss of power. Its not legal but most people block the vacuum line or remove or blank off the valve itself.

    Messing with the EGR valve on a gasoline car is difficult because it can make the car ping (spark knock) dangerously.
  • Mr_ShiftrightMr_Shiftright Sonoma, CaliforniaPosts: 57,604
    I'm not sure these old diesels even have EGR valves, do they? But anyway I don't think this would cause a pulsation in a diesel engine because a diesel engine doesn't use a throttle for air intake so it is regulated solely by the amount of fuel you put in. Vary the fuel amount, engine goes faster or slower. Therefore, vacuum leaks or more air in the system shouldn't affect it like it would a gas engine, that relies on both fuel and air to regulate engine speed through a throttle plate.

    So what I'm driving at here is that if your engine is running fast and slow, fast and slow, the fuel supply is being tampered with, and varied, by something.

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  • amonra22amonra22 Posts: 11
    at highway speeds i keep constant pressure on the gas pedal. The cruse control is inop and does not work as far as I can tell. I will remove the fuse for the cruse control to make sure. The pulsating at speeds is faint, and Im not sure you could feel it if you were not holding the steering wheel. The loss in power happens only on an incline (a hill). So a worn out injector is your best guess, as you cant see the car? Is that a fix at home thing or should I take it to a mechanic? Could you recommend a good diesel mechanic on the east bay? The power locks don't work, I have read that is a vacuum problem,does that have any bearing on my problem?
  • Mr_ShiftrightMr_Shiftright Sonoma, CaliforniaPosts: 57,604
    Well a loss of power on a hill is pretty much what any 300D will do, but I guess you are noticing more than usual?

    I'm still not sure what this pulsating is as you haven't explained if the vehicle gains and loses speed or if you are just feeling a vibration of some sort.

    ANYWAY, you should have a compression test done, and the valves adjusted (when was the last time?) least then you know that you have a basically sound engine and won't be throwing money in the wrong direction. European Auto Repair on Mill St. in San Rafael is a good diesel place.

    Many owners neglect to adjust the valves on these cars and between that and clean fuel, it can make a world of difference in how they run.

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  • 83300sd183300sd1 Posts: 1

    I just bought a 83 300 SD and I am having exactly the same problems as you are with the A/C. The fan does not stay on and if I change it to constant air, it just blows warm air. I know the compressor is working because it is removing the humidity from the air and dripping water below the car. Did you get any further in your investigation of this problem? Any advice you can give me will be GREATLY appreciated!!

  • zero3kzero3k Posts: 6
    Okay, since everybody else is posting about related issues.. I figured I'd throw my small problem in here, too.

    Recently got my A/C working again (After finding a bad ground wire behind the compressor relay on my 78 300D Euro). Blows nice cold air (I love R-12 Freon).. The only thing is, at highway speeds, this car tends to run hot. Hot being, at about the 100-110C mark. The aux fan does not kick on while driving, as far as I can tell. However, I've noticed strange things relating to the Aux fan..

    First, and what appears to be randomly, it will kick on at temperatures above 85C.. usually while sitting still for a while. Here's the strange part... if I turn the car off, the fan will stay on! It usually stops after a minute or two.. but still, my last 300D (A 1984 American model) never did this. I suspect it may be the fan relay, so I bought a new one.. however, it has not arrived yet. Any help as to what the problem could possibly be, would be greatly appreciated!
  • fusefuse Posts: 3
    OK, here's how I run my 300D on waste restaurant oil:

    [1] Get the cleanest used grease you can. I get mine from my favourite Japanese restaurant (Asian restaurants generally really do have the cleanest oil)

    [2] Try to let the oil settle as long as possible [optional]

    [3] I use a Transdapt #1028 (I'm pretty sure that's the model) Remote Oil Filter Mount which fits a regular PH 8A engine oil filter. They are the cheapest and most readily available (under $4; good for about ten fill-ups before it starts clogging, but it really lasts for over 20 fill-ups).

    [4] I pump it through the filter with a cheapo drill pump, but I'm going to get a Fill-Rite Rotary Hand Pump, which should make things much easier, as well as getting me off the electrical grid when I'm on extended trips in my Ford F250 diesel/camper, which I run the same way (although it's a [non-permissible content removed] to start, but it does have two fuel tanks - one for starting on diesel, and the other one for the bulk of the trip on veggie). My deep-cycle batteries aren't in the best shape so they would discharge about half-way through a fill-up during my last big trip (10,000miles).

    Priming has been the worst part, but the Fill-Rite hand pump is self-priming, so I'm hoping that makes this a bit easier.

    The 300D smokes a bit more with 80% veggie oil, but it starts up fine every time.
  • Mr_ShiftrightMr_Shiftright Sonoma, CaliforniaPosts: 57,604
    So you don't heat the oil while pumping it?

    I know that starting below say 40F can be tough with veggie oil. I remember trucks used to have a little ether injector handle right on the dashboard. That would be great for cold starts.

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  • dawettedawette Posts: 1
    Don't forget about the strainer in the fuel tank. It's a pain to get at, but it can clog. Best to clean or change it when the tank is near empty. You can check the flow of fuel by disconnecting the tank fuel hose where it clamps to the steel fuel line near the rear of the car. With the fuel hose gently clamped you can disconnect the hose open the clamp and the fuel should "rush" out of the line, if it dribbles, the strainer may be clogged, or the fuel level is low.
  • koolfrogkoolfrog Posts: 4
    My ,newly acquired 1983 300D has non operational door locks and cruise control ; everything else works perfectly . Could the vacuum pump be bad ? Where is the little devil located , and is it expensive to replace ?
  • Mr_ShiftrightMr_Shiftright Sonoma, CaliforniaPosts: 57,604
    No if the vacuum pump were bad you couldn't shut the car off. I'd pop off a door panel and you'll see the little vacuum motors at the bottom of the door that operate the locks. With the car running see if you get any 'suck" on the vacuum lines.

    I think you have a broken vacuum line somewhere, probably under the hood but it could be the doors.

    I doubt your cruise control has anything to do with this. They are always broken on these cars and it's the amplifier 99% of the time.

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  • burdawgburdawg Posts: 1,524
    The master element (an MB term) is in the drivers door, it controls the rest of the locking system. The drivers door is manual, in other words when you turn the key in the door it locks and unlocks the door, ditto for inside door lock operation. It also operates the master element in the door, which sends vacuum signals to the other doors, trunk, etc to lock/unlock. Other systems components are the resivoir tank, which holds a vacuum to allow several lock/unlock operations without the engine running, vacuum elements in the other doors, trunk, and perhaps the fuel fill door (don't remember if this model had that or not). The tank has a check valve in the vacuum hose leading to it to allow air to flow in one way only, so the vacuum charge will not leak out when the engine is off.
    If it's not been maintained, any of these components could be faulty. I found that a small handheld vacuum pump was very helpful in finding these problems. I could disconnect a line at one point and test a component somewhere else. The factory body service manual was almost a necessity for this.
    I agree with Shifty on the cruise control, the amplifier is almost always the culprit, but there's a possibility it's something else. Other components should be tested before making the decision to replace it.
  • ratpawsratpaws Posts: 1
    I am considering the purchase of a 1980 300D with 200k miles. The body and interior are very good so the car seems like it might not be a bad deal for $1200 canadian.
    The 2 main problems are failure to shut off when turned off ( apparently a vacuum leak issue )and the air cleaner housing is getting oil into it somehow. The levels are quite substantial (there was about 1/16 of an inch of liquid everywhere in the housing.
    The car started easily when cold and ran smoothly so I suspect that the engine clearances must not be terrible but I don't know why this oil is being forced into the air cleaner.
    Any ideas?
  • Mr_ShiftrightMr_Shiftright Sonoma, CaliforniaPosts: 57,604
    It's blow-by from worn piston rings. Diesels require tremendous compression ratios so any internal wear will show itself. Probably a tired engine with those high miles but it may run like that for a long time. It all depends on how much oil it uses. These engines can stagger along in sub-standard condition for quite a while, which is part of their charm. Just keep adding oil.

    If you have decent WARM oil pressure and you aren't belching blue smoke, you might be okay. Look for cans of oil in the trunk, or ask the owner what the oil consumption is, then double it :P

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  • My Chiltons manual does not cover R and R of rear wheel bearings. How do I do this... today?
  • amonra22amonra22 Posts: 11
    Mr Shift right,
    took my 300dt into the mechanic for a valve adjustment and with that a new valve cover gasket, had waste gate hoses replaced, and vacuum valve replaced. also new over flow hose. the loss of power on any kind of hill is now worse than before, it feels like you are dragging an anchor behind you. Was driving thru the Caldecot Tunnel and while i was driving thru Orinda/Moraga up the 24 I was at 35mph with constant pressure on the gas peddle. Question, does each cylinder have a fuel injector or is there only one? And, do you think that if I replace the injector should I also replace the injector pump?
  • Mr_ShiftrightMr_Shiftright Sonoma, CaliforniaPosts: 57,604
    Geez, I don't see how it could be WORSE by doing those things properly.

    Why don't you take the car over to European Auto Repair in San Rafael---they know what they are doing. You can't be replacing things like an injection pump without really diagnosing things, that's way too expensive for "guessing".

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  • koolfrogkoolfrog Posts: 4
    I plan to tow an utility trailer behind my 300D : What is the towing capacity of this car ? Where can you buy a hitch at a decent price ( not much help on the WEB !) ? :confuse:
  • Hey i have a 1987 300D Turbo. I bought about 10 years ago, it now has about 200K miles on it. I was wondering, does anyone had any advise on how i could improve performance on my car? how about a blow off valve? would that do more harm than good? Thanks
  • Mr_ShiftrightMr_Shiftright Sonoma, CaliforniaPosts: 57,604
    I'm not sure but I would think not very much....probably no more than the weight of a few passengers. I presume you aren't going to weigh the trailer down very much. This is after all, just a passenger car with less than 100 HP. I also bet the towing capacity is in the original owner's manual if you have one.

    There are speciality shops that can fit you with a hitch I think. You should try your local Yellow Pages.

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  • Mr_ShiftrightMr_Shiftright Sonoma, CaliforniaPosts: 57,604
    Your car should perform decently as is....short of radical modifications I can't think of much you can do to an old turbo diesel....maybe modify the turbo for more boost but as you know, that is risky on an old engine, as any deficiencies in head gaskets or valve seating or piston ring sealing will be amplified with more boost.

    Maybe you could rig up a cold air intake, use synthetic oil, inflate your tires, adjust the valves and time the injection pump---that might give you a little boost and better throttle response.

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  • Thanks for the tips
  • Mr_ShiftrightMr_Shiftright Sonoma, CaliforniaPosts: 57,604
    Well I'm not a diesel expert so maybe some diesel freak knows some tricks, but I just can't think of any that are safe or economical.

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  • benzboy1benzboy1 Posts: 1
    My mechanic told me I had severe blow-by. I went through the car, changed vacuum hose, oil, transmission fluid, and any other part could find to change. My blow-by is not so sever. Can you turnaround blow-by?
    I also think the timing is off. My mechanic tells me it to much trouble with a car that has Sever Blow By. And that I need a new engine. :shades:
  • Mr_ShiftrightMr_Shiftright Sonoma, CaliforniaPosts: 57,604
    No, blow-by is a terminal disease. It is caused by worn piston rings. YOu can test the severity of the wear by doing a cylinder leakdown test or compression test. You need special equipment to do this on a diesel.

    Injection pump timing doesn't "go off" very easily, so I'm dubious about that diagnostic. Only a real expert should ever attempt injection pump timing.

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