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Mercedes 300D Suggestions

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Comments

  • zadamszadams Posts: 11
    your engine will not stop BECAUSE your vacuum system is leaking. the vacuum system controls a lot of things including the fuel shut off, transmission functions, door locks, etc. which you may or may not know but just in case to clarify. you should look above your injection rail for a circular-ish metal object that has two vacuum lines going to it. one should be behind (windshield side) of the object and slightly difficult to access. check that line behind the shut off to see if it is disconnected. you have to find the vacuum problem or your tranny will shift rough, your fuel will not shut off with the key, your doors will not lock. do you have access to the online library? if so, you should be able to get a vacuum diagram and check your system for missing lines or leaks/disconnections. overall though, the system is way too complicated to solve over text. If you hear a air leaking sound when you are inside the car it may be as simple as one of your door locks leaking.
  • jamesleijameslei Posts: 12
    Thank you Zadams! Everything else seems to work OK except for the doors not locking when the driver's lock is closed and, of course, the engine not turning off.
    How does one access the "Online library" you mentioned? Many thanks once again. James.
  • lwoolardlwoolard Posts: 38
    Hi all my 1984 300d has just started giving me a little grief. There is a very loud scratching clanging scrubing sound coming from the rear passenger wheel. It is so loud that I can hear it inside the cabin of the car with the window closed. It is so bad that I am afraid to drive it. I took off the wheel and everything looks good and tight. What could this be? :sick:
  • Mr_ShiftrightMr_Shiftright Sonoma, CaliforniaPosts: 63,351
    Possibly rear axle CV joint. If the boot is split open, then it's probably no good for sure. They are difficult to check without pulling them off, washing them down and inspecting them.

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  • lwoolardlwoolard Posts: 38
    The boots look to be in good condition. Could it have something to do with the emergency brake, It does not work.
  • jamesleijameslei Posts: 12
    Hello. I had a similar problem with my 1982 300TD passenger side rear wheel. AIt turned out that a bit of metal (maybe from the brake shoe) was rubbing on the disk. But I only found that out when I paid to have the shoes replaced - I had earlier taken the wheel off and could see nothing wrong. Good luck!
    James.
  • Mr_ShiftrightMr_Shiftright Sonoma, CaliforniaPosts: 63,351
    Oh sure you didn't mention that before!

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  • lwoolardlwoolard Posts: 38
    Sorry :confuse: I wasn't thinking correctly at the time. From all the noise it is making I am just happy that the rearend is still on the car. Hopefully it will warm up enough tommorrow that I can check out the emergency brake. Bye the way Shifty I have read alot about bypassing the egr valve and the 3/2 way valves on top of the valve cover. Is that a safe move? Some said they did it to help with vac leaks from the 3/2 valves.
  • burdawgburdawg Posts: 1,524
    If it's like the earlier cars, and I think it is, the emergency brake shoes are separate and are inside the center of the rotor on the rear wheels. You will have to remove the rotors to get a good look at them. If the e-brake isn't working you could have a broken part rubbing inside the center of the rotor.
  • Mr_ShiftrightMr_Shiftright Sonoma, CaliforniaPosts: 63,351
    I never heard about doing that---news to me. Seems to me that vacuum leaks would be easy enough to seal. I never had any trouble with vacuum leaks on my diesel Benzes.

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  • dotishdotish Posts: 20
    I have just bought a very nice 1980 300D. Love the car, but there's a problem with the climate control. The only function working is the defroster. It blows like crazy, so I know the blower works. None of the other functions work. I found a small, well-worn pump in the trunk and found a spot under the hood from whence it came. It looks as though it was connected to heater hoses. Would the removal of this pump cause the climate control, including the blower in the other modes, not to function? I guess what I'm really fishing for is a solution to the control problem that doesn't involve trying to find a 'reasonably' priced replacement for it. I live in Texas and it won't be long before I really NEED air conditioning. Thanks for any advice I might be given.
  • brillanzebrillanze Posts: 20
    Heavens, but this is expensive stuff. My estimate for my 1983 is $1200-and that is a conservative estimate. I also have a word of caution -I live in Texas, too-get your windows tinted, and soon. If you have original windows, and they are not tinted as much as the law allows, you will not believe how hot that car will get in a hot minute in the Texas sun.

    I buy my own parts from O'Reilly or even Benz bin, but I am too old now to do my own labor. Watch your parts-you can save a lot. You will need to buy a drier with the A/C compressor and the conversion kit so it will take the new freon. As for heat, I can just let the defroster blow in the winter and the car gets plenty hot.
    Good Luck!
  • burdawgburdawg Posts: 1,524
    This is one of those things we warn people about on older Benzes here. The defroster works because when you push the defrost button it bypasses everything and sets full heat, full fan, turns on the A/C compressor (if it's working) and directs the majority of the air to the windshield.
    I suspect the pump you found is the auxiliary pump that boosts the hot coolant flow to the servo during real low temperatures. For most of us it never comes on, and not having it installed probably won't make any difference.
    There's all kind of reasons for the CC not to work. The blower fan could be bad (not likely since it works on defrost), the control assembly could be bad, you could have vacuum leaks, etc, etc. The most common recurring problem is the servo has failed, but usually if that happens you get some function other than just defrost, but it really depends on what position the servo is failed in, and then you may have A/C compressor problems to boot.
    You have your work cut out for you, and it won't be cheap.
    I have posted here many times. I had a 280SE for many years, and while it's a different body than a 300D (I assume you didn't mean a 300SD), it's very similar. The climate control and central locking systems were pretty much recurring problem areas.
    A set of FACTORY manuals is invaluable, I wouldn't have been able to keep my 280 up without them.
    Good luck.
  • car38car38 Posts: 3
    I am thinking between Buy or lease a new 300 sport 09 Mercedes.
    So, the offer is as follows:
    Buy: 2000 down and pay 570 per month for five and half years.
    Lease: Zero down and pay 530 per month for four years with 15000 mile per year limit and I have to pay 559 when I return the car after four years.
    Please advise. Thanks.
  • Mr_ShiftrightMr_Shiftright Sonoma, CaliforniaPosts: 63,351
    Oops! You're in the wrong forum. This is just for older classic cars.

    You might want to look over this list of Mercedes lease topics and pick one that suits you:

    Mercedes Lease Topics

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  • hpmctorquehpmctorque Posts: 4,600
    Although it's kind of an apples and oranges comparison, to me the cost of either buying or leasing a new Mercedes reinforces the appeal of driving an older Benz.

    Using the numbers provided by car38, leasing a new 300 Sport for 4 years would cost $26,000, or $542 per month, while buying one would cost $39,620 in payments over 5 years. I'd have to do the math, but I'd think you could save a whole lot by buying a 5, 10 or 15 year old C-Class, depending on your budget, or even an E-Class, then trading it after five years for another 5, 10, or 15 year one.

    It would be interesting to run comparisons. For the fun of it I used Edmunds Used Cars to get a quote on a 1999 C280 with the following features: 120,000 miles (12,000/year x 10), silver color, heated front seats, headlight cleaners, compact disc changer, traction control, sport suspension, power moonroof and metallic paint. Edmunds' price for this car in "outstanding" condition is $6,837, if purchased from a private party. Call it $6,800, to round to the nearest $100.

    Now even the C-Class is a fairly high maintenance car. However, if we assume this car could be resold for $1,600 in five years (Edmunds quotes $1,619 on a similar C280, with 180,000 miles, in outstanding condition) the depreciation would be $87/month, or $1,040/year (after rounding), in depreciation.

    Would someone care to make an educated guess regarding what repairs and scheduled maintenance might run (say a reasonable range) for such a car?
  • dotishdotish Posts: 20
    Thanks for your input. The blower does work, and the various control buttons do engage a servo/servos as I can hear the baffles shifting when I put my ear to the vents and push the buttons. I suspect that whatever sensing device is involved in letting the fan know it's time to come on is shot. I'm thinking the problem lies in the temperature control wheel or in a thermocouple that may be attached to that. As was mentioned, a service manual will be invaluable when I get one. Meanwhile, my daughter has found a used climate control unit that is supposed to have been tested and costs only $100. I'll see if that solves my problem when it arrives from CT. Since the compressor hasn't been run in a good while, I feel I may have to replace it as well. If need be, I'll see if a US or Japanese-made compressor will fit with minor modification and be more reliable than the Benz units. Thanks again.
  • dotishdotish Posts: 20
    Thanks brillanze, I really should get those windows tinted as soon as I can. I'm going to test my compressor today to see if it's working. I hadn't thought of a conversion kit for new refrigerant. I'll have to ask around about where to get that. I'm getting older myself, so I'd better get the hard work done soon while I can still do it. It's less and less entertaining for me to spend time lying under cars.
  • Mr_ShiftrightMr_Shiftright Sonoma, CaliforniaPosts: 63,351
    You don't have to convert your AC---you can still buy the old R12 if you are licensed to do so.

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  • burdawgburdawg Posts: 1,524
    The "servos" you hear aren't what I was talking about. What you hear are the vacuum motors (or servos, if you prefer) that control the airflow inside the plenums. The servo I was referring to is the main climate control servo that controls the whole system:
    Routes the vacuum where needed to the various vacuum motors
    Controls the blower fan speed
    Regulates the hot coolant going to the heater core
  • dotishdotish Posts: 20
    I see. Well, I think the main unit/servo is shot. I'm still wondering if the auxilliary coolant pump being disconnected might have something to do with the other functions not working.
    The control unit my daughter sent me turned out to be from a later model car and won't do the trick for me. I'm back to searching again. Thanks for your reply.
  • brakeengrbrakeengr Posts: 98
    I just finished diagnosing my "no heat" problem on my 82 300D. I had similar problems as yours- the defrost worked full heat, but the temp. wheel was doing strange things too. Turns out the PO had installed the wrong CCU (I even tried resoldering the CCU). I learnt that a W126 CCU fits into a W123- wire harness and all, and is visually the same; But a W123 CCU is actually different. So I put in a used W123 CCU, and now all functions work.
    So- make sure it is a real W123 CCU you have in there. If it is, and still does not work, you may try resoldering the contact points in it- there is a tutorial on it at mercedesshop dot com.
    As others have pointed out, the CCU is not the only problem- there are other things you may have to check. GL.
  • brakeengrbrakeengr Posts: 98
    " I learnt that a W126 CCU fits into a W123- wire harness and all, and is visually the same......"

    Sorry- I meant W124; not W126.
    The W124 unit is similar to W123....
  • dotishdotish Posts: 20
    Thanks for your reply brakeengr. I found the correct CCU on eBay for a good price today. The seller is including a relay, which is apparently located behind the glove box, that he says often goes out before the CCU and may even cause its demise. Anyone know if there's any truth in this?
  • Mr_ShiftrightMr_Shiftright Sonoma, CaliforniaPosts: 63,351
    Anything's possible but the CCU is a notorious culprit, but if the relay comes with it, what the hell. I wouldn't install both at once though, or you'll never know which one was bad.

    It took me a long time to get the AC working on my 300D and at best it remained 'adequate' but never really able to cope with anything over 85 degrees or so. And it needed re-charge annually, which is costly for R12.

    If i had it to do all over again, I'd probably not have bothered here in temperate northern CAL. But I used to like to shut all the windows to keep the racket down at highway speeds. I used to fantasize I was droning over enemy territory in a WWII 4-engine bomber. :P

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  • ghoffmanghoffman Posts: 3
    OK the dash & rear deck speakers were tricky. Just took plenty of time not to break any tabs,but I don't even want to try these without some advice.
  • jamesleijameslei Posts: 12
    Brakes have been 'soggy' for a while now. That is, the pedal goes half way to the floor before anything happens, and there is no real bite to them. Shoes seem OK, and there are no apparent brake fluid leaks. Someone suggested I needed a new master cylinder. Had one put in, but the problem remains. In fact, things are probably worse now, because if I depress the pedal a second time, the brakes become even less effective.

    Could the problem have something to do with the vacuum system? (I noticed the fellow in the garage
    using a guage to measure the vacuum 'pressure'). He is a bit lost with regard to what to try next, and so am I!

    With many thanks,
    James.
  • Mr_ShiftrightMr_Shiftright Sonoma, CaliforniaPosts: 63,351
    Yep, definitely could be the brake booster if the brake pedal STAYS HARD. If it sinks to the floor, no, then it's a hydraulic issue. Bad guess on the master cylinder.

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  • jamesleijameslei Posts: 12
    Thank you for the info Mr. Shiftright... Brake pedal (thankfully) doesn't go all the way to the floor when I apply the brakes when driving! Pardon my ignorance,
    but is the 'brake booster' you mention the same as the vacuum pump? I can see vacuum lines, but am not sure where the actual vacuum pump is located. (For a while, the engine kept running when the ignition key was turned off. Also, I pretty well gave up on all the locks some time ago and now operate them manually. Would it help my brake problem if I disconnected the vacuum line which serves the doors? Last question:
    If this would help, which is the line I should disconnect?)
  • Mr_ShiftrightMr_Shiftright Sonoma, CaliforniaPosts: 63,351
    Well if the vacuum pump isn't working properly, or there are vacuum leaks, then yes the brakes would be affected. But the power brake booster is not the same thing as the vacuum pump, no.

    I'm sure someone here could tell you exactly where the pump is. It's been so long I forget, and I sold all my repair manuals. I think it's on the driver's side of the engine, up front.

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