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Mercedes 300D Suggestions

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Comments

  • hpmctorquehpmctorque Member Posts: 4,600
    "I don't think any old Benz diesel would last any longer than a Toyota Corolla, mile for mile, with the same care given to both. What gives old Benz diesels their mythology is that they are well built. They can "look" great 30 years later."

    I think what you said here is very true, Shifty. The Mercedes diesels gained their deserved reputations at a time when most cars were not well built, and 100,000 miles, and certainly 125,000, was a real milestone. I remember when my uncle uncorked a bottle of champagne when his trusty Plymouth six turned 100,000. It was cause for celebration. Today, most (or maybe all) cars can achieve double these mileage figures, given reasonable care, and especially with synthetic oil. Therefore, today you choose a new luxury model for its styling, performance, comfort, features and exclusivity rather than for longevity. In terms of mid '70s-mid '80s cars, the Mercedes diesels really stand out, for the reasons you mentioned, and for their tasteful styling and charm. Today, an old $2,000-$4,000 Mercedes differentiates you from the sea of all-very-similar mass market car owners, and sends the message that you've beaten the odds. Whereas I don't pay attention to ordinary cars, I always take note of the old Mercedes. Well, okay, like most of you, I presume, I take note of all old cars, not just Mercedes, The difference is that an old Mercedes prompts a "Gee, it would be nice to own that" thought, whereas an old Corolla doesn't.
  • Mr_ShiftrightMr_Shiftright Member Posts: 64,481
    Very well put.

    Actually an old Benz diesel is not for everyone; if you don't get the turbo model, the old 300Ds can be dangerously slow, to the point of producing a great deal of anxiety in the driver. Also, unless the engines are in tip top shape, they puke out lots of fumes and many other drivers do not find them so charming if they are following behind.

    They also leak a lot, so I was banned from most people's driveways. I felt like a leper. And mine was a NICE car---but it didn't pass muster in suburbia.

    The real problem with many old luxury cars is, of course, that they fall into hands of people who can afford to buy them, because they are cheap, but cannot afford to maintain them, because that is not cheap. I know one couple who have the most clapped out, smoking, rattling, beat-up old Benz diesel you could imagine, with marginal tires, wired up exhaust, broken windows---but all they do is putt-putt to the grocery store 3X a week at 32 mph.

    The car refuses to die although I suspect it would like to. :P
  • panjbuilderpanjbuilder Member Posts: 1
    I would like to take the engine and trans out of a 8300TD and put in a newer one, say a 94 300 gas wagon. Any one done this and what would be the pit falls?
  • nigel6nigel6 Member Posts: 16
    hello , I hear alot about the importance of correctly adjusted valves. How difficult are they to do? I am aware you need a special wrench, can you make one ( bend it to the right shape ) ? I have a Haynes manual. Any tips ? better still , anyone near Nashville, Tennessee who could guide me. Plan on keeping the car so figure I might as well learn ! Also, I need some newer front seats as mine are pretty tatty.My car is a coupe so the seats have to tilt forward, not easy to find . Anybody know of other model/make of car that the seats may work without too much modification ? Thanks
  • Mr_ShiftrightMr_Shiftright Member Posts: 64,481
    The seats can be redone for a couple hundred bucks each. You don't have to get fancy with covering material. what happens is that the wire springs break and also the horsehair in there discomposes. So wire-up the springs and put some foam in there, and some vinyl seat covers or cloth and there you go. As for junkyard seats, I think anything that isn't too wide for the car will fit in there. You'd have to buy the seats and their tracks and you might have to do some welding to create safe seat anchors on the floor pan.

    The valve adjustment is just a matter of having the right "crowsfoot" tool (not that expensive) and being able to turn the engine over by hand or with a remote starter and using a feeler gauge. Maybe your public library has a book on this, a Haynes or Chilton's. You just do one cylinder at a time, making sure each cylinder is at top dead center, that is, both intake and exhaust valves are closed and not touching the cam lobes.
  • allman1313allman1313 Member Posts: 2
    Hey, I have a couple of questions about my 1990 300D 2.5L turbo. I'm new to the Mercedes diesel. The car has 227000 miles on it.
    1. The car changes gears very hard and often "clangs" into overdrive. Is this due to a vacuum modulator?
    2.There is also a plastic cam like piece on top of the valve cover that rides against two small wheels. The wheels are worn out. Is this a valve that controls the vacuum to the transmission? What is this called?
    3. The motor surges at idle,if in gear it runs smooth. Is this normal for mileage and just a characteristic?

    Thanks for your help
  • Mr_ShiftrightMr_Shiftright Member Posts: 64,481
    I'd say all your problems are related yes, to either vacuum leaks somewhere or a badly adjusted throttle linkage that's getting worn out.
  • swash9swash9 Member Posts: 1
    im thinking of having my 300D turbo rustprofed and undercoated to stop it from rusting out any suggettions
  • burdawgburdawg Member Posts: 1,524
    Well.....You may just be covering up rust that's already there. Without seeing the car it's hard to say, and not knowing where your from also doesn't help.
  • hpmctorquehpmctorque Member Posts: 4,600
    Swash is right; it's too late to rust proof if rusting has already begun, even if the rust isn't yet visible. So, unless the car has resided in the South or Southwest, and away from the coastal areas, since new, chances are rust proofing would be a waste of money.
  • burdawgburdawg Member Posts: 1,524
    Even out here in dry southern California, I've never seen an old Benz without some rust somewhere.
  • smerkinbsmerkinb Member Posts: 1
    Hello all, I have recently begun researching the mid 80s 300D series. I seem to be reading a lot of good things about the reliability/safety of these cars with some concerns of cost of maintenance/repairs. I am hoping someone can either point me in the direction of further researching resources or give me some ideas of specific things to watch out for. Disclaimer: I have no real experience working on cars, however learning how is one thing I am sorta looking forward to ( with some reservations about the learning curve). I have seen several listings for cars with less than 180K miles for under $3000 and many for cars with 200-260K miles under $2500. I have read that it's not unusual to be able to hit 300-450K miles with a 300D. Does anyone here think that is accurate? I live in North Carolina so don't have a ton of cold to contend with. I would be driving the car less than 5 miles one way to work each day and on weekends when I go out for errands for a few hours. One of my objectives with buying this type of car would be to get rid of my monthly car payments, but I am wondering if I go this route if I am likely to end up with never ending expensive repairs instead. Any advice for a newbie would be welcome!
  • Mr_ShiftrightMr_Shiftright Member Posts: 64,481
    We could talk for hours about this-- :P --- but my two cents is that with this type of car you should buy the best, cleanest, best documented car you can find and NOT buy a "fixer-upper". There is no upside to a fixer-upper because the values are low and they aren't going to get much better except for the cleanest and best cars.

    Any car on earth can go 400K miles, even a Yugo. All you have to do is keep pouring money into it. I think you will find that any old 300D with 400K has a lot of investment in it.

    What is remarkable about them is their build quality. Where most cars literally fall apart at 400K, a 300D can still look good, not rattle and not shred its interior. But that doesn't mean they don't break down mechanically or wear out just like any other car.

    Your average taxi cab can run as long as a Benz but it won't look at good, is my point.

    As for things to look out for:

    NEGLECT -- greasy oily engine, rusted body, dents, mildew, balding tires, filthy trunk, broken lenses, etc. Stay away from cars like this

    ENGINE -- many 300D engines are tired. Look for danger signs such as lots of oil in the air filter (blow-by) and hard starting when cold. A 300D engine should a) start up quickly and b) peg the oil pressure gauge when cold---that oil needle should literally click as it hits the highest number and the needle stop

    NOISE-- a rattly engine, noisier than usual (they aren't very quiet normally) could mean bad injectors.

    SMOKE -- 300Ds smoke a bit on acceleration but it should NOT be clouds of noxious smoke. This could be bad injectors or bad injection pump timing.

    HEAT/AC --- notoriously unreliable controls. check for ALL functions before you buy.

    CRUISE CONTROL -- notoriously unreliable. Almost always a bad amplifier located behind the console. About $100 to rebuild + labor.

    REAR SUSPENSION -- sagging back end, front end up in the air? You have a failed hydro-pneumatic compensator. Fairly big bucks.

    CLUNKING ON TURNS? -- bad CV joints in the rear axles

    HARD SHIFTING -- hard shifting is normal. Buy a neck brace, you'll need it. But LATE shifting could mean a vacuum leak or bad vacuum modulator

    DOOR LOCKS -- these are vacuum operated by little motors in the door panels. They often get slow. The motors are rebuildable and don't cost too much.

    BEST CAR TO BUY? --- Definitely choose the TURBO models. Do not pay extra for the coupe, they aren't worth more and they are less practical.

    MAINTENANCE --

    always use fuel conditioner every fill up
    use anti-gel for the fuel in cold weather
    change your fuel filters (two of them) FREQUENTLY
    make sure the valves have been adjusted at least once in the last 30K miles
    change the oil every 3,000 miles come hell or high water

    FUEL MILEAGE -- you will hear all sorts of silly claims but in fact you will get about 18-22 mpg city driving and about 22-26 highway driving

    TOP SPEED -- diesels this old don't like to rev. 75--80 mph MAX is more than enough for this car. Drive faster and you'll crack the cylinder head sooner or later.

    PARTS-- lots of stuff on the Internet, and the MB dealer still carries an amazing number of parts for this car

    REPAIR MANUALS -- you can't beat the 3-volume factory manuals, but you'll pay over $300 for them.

    SPECIAL REPAIRS -- you cannot work on the fuel injection pump. This goes to a specialist and costs about $1,500 to repair. They are very rugged and should be fine if nobody messes with them.

    Good hunting!
  • texasestexases Member Posts: 10,707
    The only other thing I might recommend is to check out a low miles/big $$ 300DD so you'll know what a good one is like. This way you can discount the 'they all do that' line from someone trying to sell you a junker.
  • fintailfintail Member Posts: 57,140
    That reminds me, the other day I got behind a powder blue early 80s 300CD turbo coupe in very nice condition...on a highway on ramp. I prepared for the worst, but the car barely smoked upon acceleration, and it was up to 60mph like any other car. It was refreshing to see one like that.
  • Mr_ShiftrightMr_Shiftright Member Posts: 64,481
    It's all about clean fuel, replacing the injectors every 100K miles, and having the injection pump timed by an expert. So few 300D owners do this.
  • supraturbo4usupraturbo4u Member Posts: 1
    i will agree, as i have an 87 diesel wagon....as you begin to introduce turbo boost, you need to have more fuel introduced to accomodate the larger volume of air. you have a fuel pressure regulator that is positive manifold pressure controlled. as the boost increases with rpms, you will only see this extra fuel if your vacuum line out of the manifold is good. check this vacuum line(it leads to the top of the fuel injection pump). if this is cracked you will have 3 problems. minimal boost due to low fuel. minimal power due to no boost. and the transmission will not shift correctly because you are giving a large throttle input which leads the transmission to believe that you are in a heavy acceleration.

    if it isn't a bad line, i would suggest that your fuel heater loop, which may not exist on earlier models could be introducing air through a bad o-ring.. i eliminated this fuel heat loop, which simply keeps a small amount of fuel warm when the block heater is utilized. it has a small fuel jacket that runs a small around of fuel into the block, it's really not necessary unless it gets well below 0, even then i've not had any difficulty in cold weather with out it!!

    hope this helps

    brett
    aircraft maint
    fix everything else that breaks tech
  • lamech777lamech777 Member Posts: 1
    Hi, I have a question. I changed the oil on my car and didn't tighten the lid on the oil filter. As a result I lost all my oil and the car died. When I refilled it, it started again but was not shifting normally and started overheating. Now I hear some kind of a knocking noise, it won't start and if it does, it does not stay on. My local mechanic told me to unplug the battery and touch the terminals together to reset the computer as well as try to degrease the oil around the spill part. I did both, but it seem to not do any good. Any suggestions on what I ought to do, and how much I should expect to spend on this?
  • burdawgburdawg Member Posts: 1,524
    You probably have a big problem. If it ran without oil until it died that knocking you hear is most likely a bad bearing (probably a rod journal), and with overheating and not being able to run for any length of time it sounds like the engine is fried. I'm not an expert on diesels, but the bottom end (rotating assembly) in a diesel is under a tremendous load with the compression that it develops. It won't last long without oil pressure.
  • Mr_ShiftrightMr_Shiftright Member Posts: 64,481
    Sounds to me like the engine is toast. That's too bad. I'm sorry :cry:

    Your car doesn't even have a computerized engine management system. That was weird advice for an '84 300TD.....oh well.....

    I guess to be sure you can have it towed to a Mercedes diesel specialist and pay the diagnostic fees. We aren't with you so we can't hear what you're hearing. If the engine is ruined, I think you just have to let the car go or buy another one just like it.
  • grandpa1943grandpa1943 Member Posts: 4
    I've read many of the posts. Have found many to be enlightening. However, there are a few (actually more than a few) things I'm not clear on.

    (1) Redline products are mentioned quite often as having the best fuel additives but rarely, if ever, is a specific one mentioned. For example, there is RL Anti-Gel, Redline 85 Plus, etc. Of the many Redline products, which is the best or most recommended for use in a 1985 Turbo.

    (2) Many come in a winterized version. How do I identify it?

    (3) What is "pour point"?

    After reading the posts I'm certain that I need fuel additives. I just don't know which one(s).

    I live in Massachusetts where so far most nights have been below 20 degrees F. Daily temperatures may reach 45 degrees but are usually at the freezing mark.

    I have a block heater but I'm not sure it works. Most mornings it will not start. When the temperature rises to 45-50 degrees it does. Unfortunately, it sits in my driveway and for the past two weeks we have had a lot of snow.

    I'm new to diesel automobiles and I need a lot of help.

    Thanks
  • Mr_ShiftrightMr_Shiftright Member Posts: 64,481
    The Redline product for diesels says "diesel conditioner" right on the label. This is not always the same as "anti-gel", which is for very cold weather.

    Also you have to change glow plugs every few years, just like spark plugs, or you won't start up very well in cold weather.

    The block heater is an excellent idea for you and you should investigate how to get it operative. I presume this is a WATER heater, not an oil heater. But if it doesn't work, just keep the battery warm with an electric heating pad isn't a bad idea, or putting a shop light under the engine to warm it up a bit.
  • rcastorcasto Member Posts: 4
    I bought a 1985 mercedes 300td not running. The previous owner said he was driving and it just died. It has 240,000 miles.When i try to start it the glow plug light comes on and goes right out.
  • Mr_ShiftrightMr_Shiftright Member Posts: 64,481
    One or more bad glow plugs would be my guess. Change 'em out. Easy and cheap.
  • zadamszadams Member Posts: 11
    you may have to get some more specific information out here. If the car "died" while it was being driven, then it stalled out becuase the engine was not combusting fuel. This either means that there is an air or fuel delivery problem to the combustion chamber, most likely fuel. A car that old could have bad or clogged injectors, a bad injector pump, a bad lift pump, etc. There are ways to isolate which.

    Also, sometimes glow plugs can come up to temperature quickly (8 seconds), so you need to be more specific than "right out". Depending on your climate and season, the glow plugs may come up to temp fast and not need to be on for long. If you are trying to start the car at 60 F or higher, it should start without the plugs, FYI. Let us know...

    zak
    1985 300td
    195,000 miles
    WVO converted
    10,000 miles
  • lydia2lydia2 Member Posts: 18
    1. Try plugging it in to get the battery, etc. charged up. Do the windows/doors lock and unlock ? Lots of stuff drains these cars and if the temps outside are cold, plugging it in is mandatory to keep everything working. Check the alternator and bushings if batteries keep failing to keep enough charge.

    2. If the battery and glow plugs are good, Is the ignition gone? I put in a generic one after using the screwdriver for a bit, when I took out the old one!

    3. When my 1983 almost stopped (max speed was 20 km) while I was driving, it was a totally dirty transmission filter, which should be changed occasionally. After sitting all night, enough drained through to start it in the am, but soon after same thing happened. The mechanic topped up my filter!!Not good, had to change it.

    4. Good luck! These are good cars.
  • rcastorcasto Member Posts: 4
    I checked it out. It was the timing chain. When turning it over, the cam doesn't turn. You can take a screwdriver and move the timing chain back and forth.Not having it apart I don't know if its broke or stretched.
  • burdawgburdawg Member Posts: 1,524
    If the chain is still on the cam gear then I doubt it's broken. It could be many things - chain is stretched past the point of the tensioner range, broken woodruff key on the crank gear, bad crank gear, broken crankshaft (does the harmonic balancer/pulley turn when the engine is turned?), many others I'm sure. The only way to know for sure is to pull the front cover and look.
  • rcastorcasto Member Posts: 4
    I took the top cover off. Pulled on the timing chain and about half of it came out. It has broke. It wouldn't pull out of the engine.Also plastic that looks like part of the slider rail came with it.
  • allman1313allman1313 Member Posts: 2
    I have been looking for a good shop manual for a 1990 2.5L turbo
    If anybody has any suggestions on what type and best place to buy it let me know
    Thanks
  • Mr_ShiftrightMr_Shiftright Member Posts: 64,481
    The dealer has the best manuals, but they are $$$.
  • texasestexases Member Posts: 10,707
    Knowing nothing about these engines - are they 'interference' engines? It just seems that with the super-high diesel compression ratios that a broken timing chain could result in big problems.
  • Mr_ShiftrightMr_Shiftright Member Posts: 64,481
    I"m amazed that timing chain wasn't rattling like the bats of hell before it broke. But then, on a 300D, how could you tell? :P
  • rcastorcasto Member Posts: 4
    I forgot to post, the first three cam towers are broke. Can I run a compressin check to see if the valves are bent? also are the cam towers replaceable? Can I put a timing chain and guide rails on without pulling the engine? sorry for all the questions, I am new to Mercedes.
  • Mr_ShiftrightMr_Shiftright Member Posts: 64,481
    I don't think it's an interference engine. I'd say your best bet is to buy a sound used head and have it rebuilt. That way, all the parts in there have been running against each other for years. If you put on new rockers over an old camshaft, not a great idea. And yes, you should be able to replace the chain, guides and sprockets without pulling the engine, presuming you haven't had damage to the crankshaft nose.

    You'll probably want the factory engine manual if you are going to tackle all this, and of course, a good machine shop to rebuild the used head.
  • burdawgburdawg Member Posts: 1,524
    I wonder if the cam towers broke and caused the timing chain to break, or if the chain bound up and broke the cam towers....
    Sounds to me like your best bet is to find a good low-mileage engine, which isn't a small task for this age of car. With 240K I'm not sure it's worth rebuilding this engine, especially with possibly catastrophic damage lurking somewhere else.
    I'm not an expert on diesels, is the cam tower casting a seperate part from the head like on the old straight six gas engine?
  • ghoffmanghoffman Member Posts: 3
    I am a "newbie" to MB, Just bought this pristine 93 from the original owner I have all service &maint, records from MB dealer so I beleive the 97,000 mi.I probably payed too much 5,000$ but , "ya gotta love this car" as I am a big guy ,6'3" 350# and this is a car I "don't have to wear" I will be replacing my front ball joints asap as the squeeking is not very MB like.Any sugestions would be appreciated
  • burdawgburdawg Member Posts: 1,524
    A ball joint squeeking? That's a new one on me, but I suppose it's possible. Isn't it more likely a rubber bushing though?
  • texasestexases Member Posts: 10,707
    Now that I found a photo 300D long block it's hard for me to imagine other than 1) timing chain breaks 2) immensely strong diesel piston rams open valves 3) Cam towers break as valves push up on camshaft.

    Unless the owner is rich and a masochist, this engine would seem to be toast. You might as well pull the head and see what happened to the pistons. Might there be a small possibility that a replacement head would do it??
  • Mr_ShiftrightMr_Shiftright Member Posts: 64,481
    I think the head was worked on previously and not done very correctly.
  • burdawgburdawg Member Posts: 1,524
    The only way I would ever consider trying to repair this engine would be a complete disassembly & inspection. Thanks for the photo, it answered my question about the cam towers.
  • timingchaintimingchain Member Posts: 13
    Does anyone know what years will interchange with a front seat for an '82 300SD (126)? I bought one from a junkyard recently, it came out of an '83 126 but it's not bolting up easily. My old one has a nice angle on the rails at the front where it bolts to the floor, where the replacement seat's rails are very straight. Do I bend them and make them work, or should I try to swap out the whole mechanical assembly?
    Thanks for the help!
  • lwoolardlwoolard Member Posts: 38
    HI all, I just purchased a 1979 300sd for $800.00 with 249000 miles on it. There is one issue with the car that I could use some help with. The brake booster, door locks, climate control, and engine shut off, which all work on vacuum do not work. Also the transmission will not shift at low rpms. After driving the car for a few miles, everything work beautifully except the trans shifting. I took the brake booster line off at the vacuum pump and noticed the pump is pulling a little vacuum and it increased as the engine rpms where increased. I don't have a vacuum tester. I was wondering where my problem might be. Does the transmission shift on vacuum or is this another issue. Is there a vacuum module on this model, if so where is it? Also when I cut the key off and rev the engine it will shut off.
  • Mr_ShiftrightMr_Shiftright Member Posts: 64,481
    You either have a bad vacuum pump or lots of vacuum leaks. All your problems are related to vacuum loss, including shifting. Diesel engines use vacuum pumps because they produce very little manifold vacuum, as they don't generally use throttle butterfly plates. Your vacuum pump should be putting out I think around 20 inches of vacuum after one minute of start up.
  • ghoffmanghoffman Member Posts: 3
    Dawg! You ware right it was bushings, But in 200,000 mi I will be ready! squeaks are gone. thanks
  • lwoolardlwoolard Member Posts: 38
    Thanks, I was thinking the vacuum pump was bad. I see they sell rebuild kits online. Is that the way to go or do I need a new or remanufactored one. Is there a way to tell? I checked all the vacuum lines that i could find and all seemed to be ok. Is there a valve on the tranny that could be bad?
  • Mr_ShiftrightMr_Shiftright Member Posts: 64,481
    I haven't been under one of those old babies in a while but I think there is a vacuum modulator for the transmission, yes. Where it is exactly I don't recall. But sure, any vacuum line dangling off or cracked can screw up everything. Sure you can rebuild the vacuum pump---it's not a 100% success rate but I shudder to think what a new one costs.
  • brakeengrbrakeengr Member Posts: 98
    I had my vacuum pump rebuilt with much success- solved a lot of the vacuum related problems; and inexpensive!
  • lwoolardlwoolard Member Posts: 38
    Ok I pulled the top off the vacuum pump and found the diafram was cracked in 3 places. Bought a new diafram and the pump works great. I got my locks, climate control, brake booster, engine shut-off all back and they work surprisingly well given the age of the car. Cost $40.00 that's the good news. Here's the bad. The transmission will only shift a high rpm's from 1st to 2nd at 20 mph, 2nd to 3rd, 45 mph, 3rd to 4th 62 mph. Then when you slow down to 53 mph it down shifts back to 3rd. I unhooked the kickdown under the gas pedal and still no difference. I have examined all the vac lines and all look good. Does anyone have any suggestions? I looked at the tranny fluid and it is not brown or burnt smelling, it's red and fresh looking.
  • epicyclesepicycles Member Posts: 7
    have you had a close look at the little plastic valve with three vacuum pipes, on top of the rocker cover, next to (and operated by) part of the accelerator mechanism. It may be leaking and would cause the gear shifting symptoms described. While waiting for a part I took a deep breath (as noone could tell me if it was wise) and removed it, temporarily sealed the pipes, the outcome was gear changes at low revs.
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