Mercedes 300D Suggestions

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  • bcparsonsbcparsons Member Posts: 18
    I have a 1984 300D Turbo with 184,000 miles. I bought it with 21,000 miles in 1987. I have done most of the maintenance myself after the warranty but the vacumn system is playing with me right now. The doors will lock but after only 10 or 15 minutes only the drivers door will unlock. The cruise control does not work and the sunroof will open but not close. And it shifts a little rough sometimes. I have replaces all the plastic and rubber vacumn lines in the engine compartment. Made a huge difference but did not solve the problem.I'm guessing that I will gave to take the door panels off to look at the vacumn bags.
    Your suggestions will be appreciated.
  • Mr_ShiftrightMr_Shiftright Member Posts: 64,481
    yeah, you're still leaking vacuum somewhere. Loss of cruise control and rough shifting confirm this. I believe those little vacuum motors in the door are rebuildable with kits from either dealer or aftermarket. Also there is a vacuum reservoir attached (as I recall) near the firewall) which you must check for leaks as well.
  • burdawgburdawg Member Posts: 1,524
    If I recall, the vacuum storage tank for the locks is in the trunk, but I'm not 100% sure. Usually that's not the problem, it's either the master element in the drivers door or a leaking diaphragm on one of the door solenoids.
    The cruise control could be a vacuum problem but it could also be something else like the amplifier or speed sensor.
    As for the sunroof, does the motor run when you try to close it? If not, check the switch and motor. If you hear the motor run, then I would have a look at the teleflex cable that operates it. It's a big job, you will have to disconnect it from the sunroof and pull it out to inspect it. They usually go bad at the motor end which has a hard spring that acts as a worm gear and shock absorber.
    You could really use a factory body manual for these kind of repairs.
  • Mr_ShiftrightMr_Shiftright Member Posts: 64,481
    Amplifier failure is a common problem with the cruise control. I think you can send them off to be rebuilt for $150 or so. Some people have had luck taking them out and just re-soldering everything by touching each weld with an iron. I believe they are just behind the radio console if I recall.

    I was assuming that the cruise worked just before the vacuum problems appeared----but maybe I read that wrong.

    Quite frankly, using cruise control on these cars gets very annoying as they are so down on power that you are constantly downshifting...also on cruise you forget that you need a running start to get up hills. Once mine broke, I never bothered to repair it for this reason.
  • bcparsonsbcparsons Member Posts: 18
    ok, so now I pull the door panels off and check the lines and motors there. Where is the reservoir on the firewall, behing the consol or in the engine carpartment? I haven't started taking things apart yet but I 've done a visual and can't find the vacumn tank in the trunk.
  • bcparsonsbcparsons Member Posts: 18
    I just got back from a 5 hour interstate trip and sure could have used the cruise, yes it did work before the vacumn problems turned up. This car loves cruising at 75 or 80 and you all know how stiff the accelarator can get. It certainly is not that important.
  • bcparsonsbcparsons Member Posts: 18
    I'm thinking that it might be the switch since it opens but does not close. Thank you for the manual mechanism. Is there a way to check the conductivity of the switch? I will check it though to see if the motor runs.
    Where is the speed sensor and amplifier for the cruise control and can you tell me of another repair manual other than the Haynes that tells me what the Haynes doesn't besides the factory manual and where can I get a factory manual? I must be crazy thinking about the manual but I went for the factory manuals for my 1972 BMW 2002 and there is nothing better. $150 well spent.
  • Mr_ShiftrightMr_Shiftright Member Posts: 64,481
    The 3 volume set of manuals is really worth it, but they aren't cheap; you have to think of them as an investment that pays for itself over time. EVERYTHING is in those manuals. One is for engine, one chassis and I think one is maintenance.

    You really don't want to go faster than 80 mph in these old diesels. They aren't as happy at high rpm as modern diesels are, and if you run them up too high for too too long, you risk damage to the cylinder head. Really a 300D engine is useless over 4,000 rpm.
  • burdawgburdawg Member Posts: 1,524
    I would pull the switch out and check it with an ohmeter for continuity in both positions.
    I'm not sure about that body but in others the vacuum storage tank for the locks is in the trunk up under the package shelf. It should be a plastic thing with a bunch of bubbles molded into it.
    Many models also have another another vacuum storage tank for the climate control, cruise control, etc. It's smaller (since those things are used when it's running) and usually in the front of the body on the firewall or behind one of the fenders.
    For most MB models the Haynes or Chiltons manuals are not very useful, especially for the body systems. They don't have the detail, wiring diagrams, vacuum diagrams, etc.
    For troubleshooting the vacuum systems one of those Mityvac handheld vacuum pumps is very useful.
  • countsmackula1countsmackula1 Member Posts: 61
    Just bought on Monday w/ 277,000 miles.Odometer stopped at 271,000, but owner kept meticulous records. First of all, I want to thank Mr. Shiftright for his great tips and info that he is sharing. I've learned more today than form all my other sources combine. Next, a question: what kind of cost would i be looking at for a A/C repair, assuing the auto feature is at fault? It's been converted to RF-134. Also, is gauge failure on these cars a common problem? my work on occasion. the speedo fuel, temp, and tach work all the time, however. i'd like to fix the odo, as i plan to keep this car as long as it is feasible. I paid $2400 for it. thanks!
  • Mr_ShiftrightMr_Shiftright Member Posts: 64,481
    No, gauge failure isn't common. Probably a little gear in the speedo/odo head has worn out. You can pop them out and send them for rebuilding. There may be some trick to fix them yourself, dunno, never tried. Have you visited these pages yet? Bookmark 'em!

    http://diymbrepair.com/

    http://dieselgiant.com/mercedes_diesel_maintenance_tips.htm

    The AC question is really hard to answer unless you've started some kind of "diagnostic tree" to figure out what isn't working and why. First thing is to determine if the compressor is rotating, and if so, if there's any refrigerant in the system, and if so, if the compressor clutch is engaging. You need to have a working and fully charged AC compressor before you can diagnose the rest.

    I don't know your climate locally or your needs, but unless AC is critical, you may end up spending a lot of money to rejuvenate an AC system that was, at best, pretty mediocre right from the factory.
  • 93integra93integra Member Posts: 16
    just curious all, when the engine is at TDC, and the camsprocket mark is lined up, at what timing mark on the harmonic balancer should it be? I'd like to install the balancer back on the car correctly, I know theres only two ways it will line up but don't want to have to take it off again once its on. Also, I was looking under the dash on the drivers side, theres a black "L" shaped tubing that connects to the side close to the door. There's also another longer piece of tubing close by, one end is connect to a part but the other end is just hanging there, is it suppose to connect to somewhere?
  • brightbusbrightbus Member Posts: 19
    hey im glad I found this forum

    i'm 17 and i just purchased a 76 mercedes 300d, for $701.99, it is my first car. it has 107,106 miles, so far the only problems that are wrong with it is my interior dash lights don't work, and my cassete deck (after market) doesnt work. for the dash lights i was wondering if it could be a fuse. also wondering if it could be the same for the deck. thanks for any and all help.
  • Mr_ShiftrightMr_Shiftright Member Posts: 64,481
    Make sure you check the dimmer switch for the panel lights...I think it's one of those little twisty knobs that stick out of the clear plastic shield that covers the instruments. If not, check the fuse, and if that's okay, you can pop the whole instrument cluster out very easily and replace the little bulbs (they twist in and out). You can get these at the Mercedes dealer.

    The tape deck has its own fuse no doubt, probably an in-line cartridge off the hot wire.
  • fintailfintail Member Posts: 58,604
    I actually have a question...I know some MB diesels around the late 80s/early 90s were less than awesome. Was the engine in a 92 300D the good kind or the crap kind? I have a friend looking at one, and I honestly don't know. I'm a gasser guy I guess.
  • Mr_ShiftrightMr_Shiftright Member Posts: 64,481
    It's the 350D that you don't want. The 300D at that time was I think a 2.5 liter.
  • fintailfintail Member Posts: 58,604
    Yeah, the early 90s ones had the little vents in the front fenders IIRC. I didn't know if all the issues with the 350 might have affected the 124 cars, which are fairly scarce. He wants me to look at it with him, but I want to know if he should even bother first.
  • Mr_ShiftrightMr_Shiftright Member Posts: 64,481
    If he's hot for a Benz diesel, you can't do better than the later 300E diesels (was that 1994 onwards?). The earlier 2.5 turbos are okay but rather anemic on power---only 120HP in a heavy car...good in the city but a bit sluggish on the freeway to say the least. The later 300E diesel has a 4-valve head (first for a diesel I think) and is a good performer and FABULOUS in economy. Rumor has it you can go almost 800 miles on one fillup.

    If it's a 350SD, I wouldn't even bother to look at it--let someone else suffer in your behalf.
  • fintailfintail Member Posts: 58,604
    Yeah I think the engine changed in 94 for the facelift, that makes sense...I think it lost the fender vents too. This guy's soon-to-be wife has always wanted a MB, and her cousin runs a high end MB/Porsche shop. This car belongs to a client who is moving overseas and will sell it cheap, and the car has been gone over thoroughly by the shop. I think he can get it for 4-5K, and it's very clean. I might go look with him. I might suggest a later 124 or a 210 too if she's set on a diesel...otherwise I'll steer him towards a normal 124, as they seem to be becoming worth very little anymore, yet are superb cars if maintained.
  • Mr_ShiftrightMr_Shiftright Member Posts: 64,481
    I'm not sure why, with current fuel prices, anyone would want an older diesel, but a 300E is at least justifiable. A 2.5 Benz diesel will average only 29 mpg but a 300E diesel should get up to 34 mpg, which is pretty great for a big car. A 350SD isn't all that economical, probably no better than the old W123s we discuss here.
  • ty300dty300d Member Posts: 2
    i sent you an email about my mercedes benz it is a 1980 300D. i was also wondering if it is possible to put a turbo on them? because deisel engines run alot better with turbos.
  • ty300dty300d Member Posts: 2
    if my ignition dosent turn off my car and i have to go under the hood and push the engine stop to turn it off. dose anyone know why this is or is my ignition just messed up. if you could send me an email to Ty_181@hotmail.com
    thanks
  • brightbusbrightbus Member Posts: 19
    for my dash ive figured out that the lamps have probably gone bad, because i checked the fuse, and the fuse is good. as for the tape deck, i figure either the deck is bad, or the wiring is bad, because i checked both the car fuse for the radio, and the radio's own fuse, and they are both good. any suggestions???
  • Mr_ShiftrightMr_Shiftright Member Posts: 64,481
    Vacuum leak.
  • brightbusbrightbus Member Posts: 19
    k, i got my radio fixed thanks, i have another question, im getting new fuel filters, and im going to get someone else to put them in for me, but where are they at, I can't find them, and also, how hard/expensive is it to get glow plugs replaced? because I think I need to replace the ones in the car
  • brightbusbrightbus Member Posts: 19
    oh yeah, i forgot to say that my glow plug indicator does not come on at all, but that my engine starts up fine cold/warm, except for like twice. this is why i wanted to know if i needed to replace all 5 glow plugs
  • bumpybumpy Member Posts: 4,425
    If it's a 350SD, I wouldn't even bother to look at it--let someone else suffer in your behalf.

    I saw one of those this morning. What sort of misery do they entail? Maintenance hogs, or just underbuilt?
  • fintailfintail Member Posts: 58,604
    They had leakage problems, I know I've heard that much.

    Now I have someone else who emailed me to find them a W210 diesel. I'll just pull it out of my imaginary car hat....they are rarer than W202 AMG cars it seems.
  • bumpybumpy Member Posts: 4,425
    The bugeye Es? I've seen a few of those as oilburners... real estate agent I used to buy my house a few years ago has a white one now.
  • fintailfintail Member Posts: 58,604
    Yep, a bugeye E diesel. They seem to be outnumbered by gassers by at least 10:1. Apparently the 98-99 models are quite good.
  • Mr_ShiftrightMr_Shiftright Member Posts: 64,481
    bad engines
  • brightbusbrightbus Member Posts: 19
    ok, i got my car checked out and found out that my glow plugs are actually ok, the bad part is my alternator is going back. other day it wouldn't start and had to get it jumped. as i said, found out it was the alternator. i got the price on one, but about how much do you think it would cost for labor to put the alternator in?
  • Mr_ShiftrightMr_Shiftright Member Posts: 64,481
    Probably one hour.
  • brightbusbrightbus Member Posts: 19
    about what 70-80+, also would it be better to get a new alternator or get the one in there fixed?
  • Mr_ShiftrightMr_Shiftright Member Posts: 64,481
    That's really a price comparison question...I'd say either a quality rebuild or a new alternator...I wouldn't go through all the trouble of taking it out just to patch it up.....although...I will say that the nice thing about a diesel is that you can run all day (but not night) without an alternator, as long as you don't shut the engine off.

    You know, if it were ten minutes in and out, I'd take a chance on patching up an old alternator (new brushes, cleaning, whatever) but not on one where you have to dig it out of the engine compartment.
  • brightbusbrightbus Member Posts: 19
    ok, i was going to take it to the shop tomm, got one of those garages that specialize in alternator/generator repair/replacement, wanted to go today, but closed because of memorial day. thing is car wouldnt start last saturday, had to get a jump, got checked out and said yep it was my alternator. ive been kinda cautious, because i didnt know how long it would run before the alternator drained the battery, it is still running today though, so im hopin itl run till tomm when i can get it fixed
  • fintailfintail Member Posts: 58,604
    Taking it to a local rebuild place would be good. The generator on my fintail failed some years ago, and I took it to a local shop (as a new one was something like $700) - they did a fine job and even cleaned it. Something like 7 years later, it still works fine.
  • Mr_ShiftrightMr_Shiftright Member Posts: 64,481
    Well it'll fun forever without an alternator or a battery...but it won't re-start if you shut it off, so your neighbors might get mad :P
  • brightbusbrightbus Member Posts: 19
    well i took it to an alternator specialist, and they said it was my battery, said my alternator was good and was putting out 14 amps, said my battery was bad, so i got my battery replaced and it has been running good ever since. btw, they said the batter in there wasent even a car battery, it was a boat battery! would this effect performance wheather it was good or bad?
  • Mr_ShiftrightMr_Shiftright Member Posts: 64,481
    not on a diesel. You only need the battery to start the car. But a bad battery in general can stress your alternator. Never, ever try to charge up a completely dead battery only using your alternator.
  • burdawgburdawg Member Posts: 1,524
    I'm sure they meant 14 volts, not amps. The battery being a "boat" battery doesn't mean much, just that it's a deep cycle RV/marine battery, with a higher reserve capacity.
  • moparkidmoparkid Member Posts: 5
    I recently purchased an 84 300D for $1500. The car is in really great shape, considering it has 325K on the clock. The body is 99.9% rust free, the interior is good (dash has a few cracks, and the plastic covering the guages likes to fall off), and it runs great, I've had it at 5500 RPM which I find amazing for a deisel of any mileage(if it's a cold morning, it might take a few tries to start, but once warm it's fine). I really like this car, and hope to drive it for many years to come. my greatest concern at this point is the transmission. it doesn't slip as far as I can tell(though it does spin roughly 4000 RPM @ 80 MPH--is this right?), but it shifts harshly(often producing a loud "thud", especially when slowing to a stop as it downshifts to first presumably) and under hard acceleration will sometimes skip second gear completely. it also leaks a significant amount of ATF(the source of which I have yet to locate). it seems to smooth out a bit after sustained highway driving, but I fear it's days are numbered. Fortunatly, I recently rebuilt a GM 4T60-E (FWD) and a 4L60-E(RWD) at school. Are rebuild parts available for this transmission? if so, is it an especially complicated transmission to rebuild? would any specialty tools or equiptment be required? on a separate topic, has anyone converted their 300D to run on cooking oil? I would really like to buy a kit, especially now that deisel costs more than premium gas. I am really not concerned with performance, simply optimal fuel economy. any recomendations or related advice would be greatly appreciated. long live internal combustion!
  • Mr_ShiftrightMr_Shiftright Member Posts: 64,481
    You could probably rebuild the transmission, sure. Just take your time and keep everything clean. I'd certainly get the workshop manual for it, though, in case you forget where some little bit or piece goes. This transmission is traditionally clunky and ineffecient. Perhaps you might check the vacuum device that modulates the shifting. Maybe you can just get away with a re-seal.

    As for driving it a long time, if you drive it at 5500 rpm, you won't be driving it for a long time. Old diesels like that do not enjoy high rpm and you'll crack the cylinder head for sure...besides, the power on a 300D is all gone at 4400 rpm or so, and that's plenty fast in 4th gear for that car's suspension and brakes.

    There are a LOT of websites that talk about cooking oil conversions and what equipment you'll need. Mostly you'll need to filter it, and heat it up a bit before starting the car (or have a dual-fuel system to start on diesel fuel and then switch to cooking oil). You biggest obstactle after installing the tech you need is mostly just fetching and hauling the greasy stuff home and pre-treating it.

    You sorta need time on your hands for this kind of thing.

    Anyway, lay off the rpms would be my best advice and good luck with the car. It will serve you well if you take care of it.
  • agh3092agh3092 Member Posts: 1
    How does one remove the axle shaft from a 1979 300D.
    I have removed the rear cover and have taken the c-clip out, and also the outer bolt on the axle in the center of the hub. Is there any way to get the axle out without having to take the entire rear suspension out. This is the passenger side axle.
    Thanks in advance and any help or suggestions would be greatly appreciated.
    Thanks
  • moparkidmoparkid Member Posts: 5
    well, I didn't mean I was driving it at 5500, but I popped it into nuetral once when the cruise was on, accidentally, and thats how high it revved, lol. still impressed me though, even modern pickup truck deisels can't touch that. anyway, I want a dual tank system for sure (I live in WI and go to school in WY, gets a little chilly sometimes), but I don't have a great deal of money to spend on the kit itself. do you know of any good brands, specifically? I'm sure I could install it, it seems pretty straightforward, but what besides filtering do you need to do to the oil beforehand? what kind of filters am I going to need? would it be possible to carry these filters on-board so I could essentially put the raw cooking oil into the car? I don't care if it takes an hour to fill up, as long as it's free lol. also, I have seen a few 300's that appear to be the same body style as mine, but with more modern (and more attractive)looking headlights and bumpers. how long was this body style produced, and how hard would it be to find these newer peices? how many different designs were produced? are there any other components that would need to be changed to accomodate them? I think the car's looks could be vastly improved (not that it's ugly now, just....dated) with some subtle modification (I was thinking maybe shave the side moulding and driprails, followed by some fresh pearl white) so the laidies like it as much as I do. sorry about the barrage of questions, but I'm excited as a schoolgirl on the first day of kindergarden...man, I need a hobby.
  • Mr_ShiftrightMr_Shiftright Member Posts: 64,481
    Well the biodiesel stuff is a whole other universe you have to study. I'm sure with google you can come up with all your answers. The people you need to talk to are the "pioneers", not the "talkers", that is, people who've DONE it not the ones waxing poetic as idealistic futurists.

    The ones who have done it have worked out the kinks and also know the upsides and downsides (there's always a downside). I do dimly recall that all the stuff you need costs around $700, but that's just a wild guess.

    It's kinda hard to make a sports car out of a German brick. Nothing worse than a 60 year old man dressed like he was 25. :P

    For me personally, with an old Benz diesel, I'd go for some new wheels, and get those yellow fog lights. Maybe I'd flat black the rocker panels or even two-tone the car below the belt line like more modern Benzes. Anything to fool the eye and get rid of those slabs of vertical metal that look like walls of ice in the Arctic.

    You need to make the car look lower I think....even a darker top than the body paint might help.

    But you've got the right attitude...running on cooking oil IS a hobby, where the hours spent are for fun, not profit.
  • brakeengrbrakeengr Member Posts: 98
    1982 300D turbo with 246K miles- beautiful car.
    My door locks won't work (except when engine is on- then 3 of the 4 doors lock when I press the driver side knob). Heat does not work (cool setting works fine). Lately the brake pedal is hard- in fact, sometimes when I just start the car I hardly have brakes until I pump a few times.

    Question is- are all these 3 issues related? Can they all be caused by a single vacuum leak somewhere? And how do I go about checking for vacuum leak? Thanks.
  • Mr_ShiftrightMr_Shiftright Member Posts: 64,481
    Yep they surely do sound related to a rather LARGE vacuum leak, probably the power brake booster, presuming the large vacuum hose to the booster is intact and tight.
  • mjune512mjune512 Member Posts: 2
    I just got a "new" 81 mercedes 300D. Ive been noticing a lot of smoke coming from under the hood but I only notice it when Im stopped. I saw that there was some oil leaking out around my ventilation hose so I changed that and the leak stopped. However it is still smoking and I noticed a lot of cooked oil near the back of the block under the air filter. Also, I just checked my oil level, which I havent done often enough, and it was almost dry. I put 6qts in about 2 months ago and I havent noticed an alarming amount of oil underneath the car so I assume its leaking and cooking off when I drive. I really appreciate any input.
  • Mr_ShiftrightMr_Shiftright Member Posts: 64,481
    Well it's probably got a gazillion miles on it and you're burning oil from worn piston rings or losing it through blow-by. I bet there's a lot of oil in the air filter, too, so you'd better check.

    You'll just have to live with it and check the oil more frequently and keep your air filter clean.
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