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Mercedes 300D Suggestions



  • burdawgburdawg Posts: 1,524
    I thought the mono valve was on earlier Climate Control 1 cars?
  • That is correct the monovalve is on the climate control 1 cars. But I did get heat!!!!!!!!! This is how I got it. The servo is not working as I could not hear it at all when engaging the heat. But my servo is not leaking at all so all I did was buy a connector and tied the line coming off of the Auxiliary water pump to the line directly in front of it.(looking from the passenger side of the car it is the line on the right side of the servo) This bypassed the servo and i got instant heat. Now I only have heat, which is ok for the winter, so when it warms up, I'll open up the servo and see if I can free up the heater valve. If not I quess I can go back to the original hook-up or buy a new servo. Thanks for all your help. :) By the way the fix only cost me $3.82. :shades:
  • Another problem that I have noticed with the cold weather we have had is that my 1979 300sd has a hard time starting. I changed the glow plugs and no change. I went to diesel giant and learned how to test the relay and related things. I found out that my 2nd and 3rd glow plug are the only two working. The problem is in the wires. My question is does anyone know where I can buy a new glow plug wiring harness? I can not find one anywhere online. Thanks.
  • Hi All no need for the wiring harness as I took mine off and replaced the glow plug end loops as the ones on mine were almost half way broke off. She seemed to fire-up well after I got everything back together. But the glow plug light still blinks for a while after she starts. Not all times but mostly when I first start her up, any suggestions as to why? The battery is new, the glow plugs are new and the wiring is good, also there is 12.5-13 volts coming off the glow plug relay so it is fine. I love working on this old beauty!! :)
  • I am having much the same problem. I have a 1983 300D (odometer was stopped at 317,000 mi) that I bought at an auction several years ago. I have driven it like crazy and done very little maintenance. However, I have noticed that I have a hard time getting it going in the mornings; it starts up fine, but does not respond when I put it in gear until it has been warmed up for at least 15 minutes. Sometimes if I re-start it, it runs better. But it runs very rough (especially after stops and up hills) until it really warms up, then it is fine the rest of the day. I suppose that I should at least change the glow plugs and probably change out the transmission fluid and filter. (I haven't done either in the 3 years that I have had it). However, I already have a running tab of about $4000.00 to restore this car if I want to keep it--I am worried that I am pulling low compression and will need engine overhaul -which I would not want to invest in this car. Any ideas? Shoud I count my lucky stars and part this car out? :confuse:
  • hpmctorquehpmctorque Posts: 4,600
    I'm not one for parting with a car early, but in this case, yes, I'd part with this car now. It's time, in my opinion. However, I consider Shifty and Fintail to be the real authorities on your 300D, so I'd defer to their suggestions.
  • Hey, what are you complaining about, it starts, it likes to be warm (all old cars and people do), and you've hardly touched it. Maybe get the valves adjusted but if it's not burning a ton of oil (more than 1 quart every 3k) then let it warm up. Old cars are like and old wife, tired, saggy and slow to start, sure a new one would be fun but it's going to cost you!
  • fintailfintail Posts: 47,734
    I don't know a lot about diesels, but if he simply wants to do a glow plug change and a tranny flush before making a decision, I'd say let him do it, those aren't very expensive fixes. A miled up W123 isn't going to be worth a fortune in parts anyway, so I think he should drive it until it has some kind of catastrophic failure.
  • Mr_ShiftrightMr_Shiftright Sonoma, CaliforniaPosts: 64,490
    Sure no harm in glow plugs and trans service and a valve adjustment. My guess is that you need new injectors. They DO wear out you know.

    You might try some toxic injector cleaner---not that whimpy stuff off the shelf, ,but something like BGK-44. Ask a truck diesel shop to recommend something and if he hands you a can while wearing a HAMZAT suit, that's the stuff you want!

    But if a $250 investment does no good, definitely bail out of this car. You can buy these very cheaply right now due to the drop in gasoline prices and the apparent tailing off of the "veggie oil" craze.
  • I am looking for a (cheap!) 3rd vehicle, for hauling stuff from Home Depot, towing a small (less than 1000 lbs.) boat, back-up for the main vehicle as the 2nd (a Crossfire) won't fit all 3 family members, etc. Live in coastal Virginia, so, winters are mild, but, summers hot & humid.

    Looking at 2 300 TE's, one w/about 100K and another w/about 145K. Questions: how can I tell if it is 4Matic? One claims to be, but, there is no badge that says there a gage, controller, etc., in the instrument panel that tells me? If RWD, how to tell if it has limited slip diff, which is apparently an option on these?

    Both seem to sag at the rear end, which could be problematic for hauling this just a matter of replacing shocks or is there a likelihood of more involved repairs?

    Any other items which I should have mechanic look at when considering these vehicles? Used to have a 300D sedan (1977), so, I am not a 'virgin' when it comes to older MBs.

    thanks, ray
  • Mr_ShiftrightMr_Shiftright Sonoma, CaliforniaPosts: 64,490
    You'd don't want a 4Matic. You don't even want to park on a street near a 4matic.
  • fintailfintail Posts: 47,734
    If there's no badge, it's probably not a 4-Matic unless the panel was painted and the badge not replaced or something. I'd run it through a VIN decoder to be sure.

    The sagging rear end is probably a defective load leveler.

    As Shifty says, you probably don't want to mess with the early 4-Matic. Failure is almost guaranteed. The system wasn't done right until the 1998+ models, but those have their own set of issues.
  • OK, I get the 'no 4Matic' message. Don't have to hit me over the head w/a 2x4. I would be happy w/RWD as long as it has limited slip differential. Anyway I can tell if it has this feature before taking it to my mechanic? He will charge me $95 to do a full pre-buy insection, which is fine; however, I don't need to do that if there is no limited slip differential/traction control.

    Thanks, Ray
  • Mr_ShiftrightMr_Shiftright Sonoma, CaliforniaPosts: 64,490
    jack up both rear wheels. Put trans. in neutral (or put car on a lift). Spin one rear wheel. If the opposite rear wheel spins in the SAME direction, it's a LSD. If it spins opposite, it's not.

    Sorry to beat you over the head, but failure to hear the 4Matic message can result in financial disaster for the buyer, so I wanted to make that pretty clear.
  • fintailfintail Posts: 47,734
    I don't know how garbled the results will be, but run the VIN through This Decoder and it should tell you how the car is equipped.
  • Well, I dithered too long and the non-4Matic sold. Called last night to make arrangements to pick it up for my mechanic to look at and the seller said somebody bought it at lunchtime. Drove a couple of hours to see it, took one look and bought it on the spot. It was in very good condition exterior and interior, w/99K miles. There just was no record of where it had been for 11 years and I was puzzled by that, plus, the hvac blower didn't work, which meant I couldn't tell how well the ac system would work before making the purchase. I spent a lot on my 300D on the ac and never really got a good result.

    I have a line on a couple '95 E320 wagons, both non-4Matic (See? I learn...) Any surprises about which I should be aware? Thanks for any info...

  • Mr_ShiftrightMr_Shiftright Sonoma, CaliforniaPosts: 64,490
    Well being aware of a malfunctioning HVAC system was a good idea---that can set you back thousands of dollars.

    I'd say HVAC, engine or systems warning lights and various electrical glitches are what you should be keeping a sharp eye for. If I were buying one of these older Benzes, I'd take a long long test ride and I'll play with every knob and switch over and over again.
  • fintailfintail Posts: 47,734
    That's the last year for the 124, those are good cars. The 124 is widely considered the last series to be built to a standard rather than to a cost.

    As Shifty says, HVAC can be problematic...I think those cars can have wiring harness issues too. Window switches and regulators can fail - not grossly expensive, but annoying. As with any automatic of that age, proof of maintenance is something I would look for.
  • Hi all. I just purchased a 1984 300dt with 206,000 on the clock. The car was garaged all its life and maintained perfectly as it is a two owner car. The previous owner bought it at 60,000 miles and owned it for 16 years. It sat in there garage for 2 years. The day I looked at it, it was 19 degrees F out with snow on the ground. I put the battery out of my 1979 SD in it and it started in not even one second with no smoke and did not shake rattle or anything ran perfect. I gave the owner $1,000 for it and drove it home. Now is the fun part. The only problem that I have is the door locks. They had been unhooked because they had quit working properly. There is no vacuum at all going to them but the passenger side front and the driver side rear keep locking when you pull the outside handle to open the door. I am ok locking and unlocking manuely but why are those two locks doing this. You unlock them manuely and you may be able to open the door once or twice then the lock goes down on its own. This only happens on these two locks, any answers would be great.
  • Mr_ShiftrightMr_Shiftright Sonoma, CaliforniaPosts: 64,490
    You need to pop the panels off and see what's up in there. Maybe they disconnected not just the vacuum motors but also the lock linkages. Just unscrew the arm rest, the surround on the door pull, and the chrome surround on the door lock (on the edge of the door as you open it), then unscrew the lifter knob, pop off the panel and lift UP and it's off. Simple. Then you can observe what is going on in there.

    It's not a good idea to disconnect the vacuum system. If it leaks, your engine won't shut off and your car won't shift correctly.

    These little vacuum motors are rebuildable and you can get kits for them for not much money.

    It's great that the engine starts right up. If a Benz diesel cranks and cranks before starting, that's usually a very bad sign.
  • Thanks for the quick response I will do that. Yes it started right up as if it had already been running but I know it had not. I think its going to be a good car. It is the best one I have owned anyway. I did take the panel off the front door and there was a black plastic piece up at the top of the door down from the the stem that sticks out of the door, that the knob screws on. This piece seemed to be broken but i could not extract it from the door. I don't know what it is for it did not look to have any purpose at all. Any suggestions?
  • Mr_ShiftrightMr_Shiftright Sonoma, CaliforniaPosts: 64,490
    I dunno. It's been a long time since I've been in one of those doors.
  • Hi -
    Does anyone know what is the normal braking distance (from 60 MPH) for the 1981 Mercedes 300 Diesel?
    Thanks -
  • Mr_ShiftrightMr_Shiftright Sonoma, CaliforniaPosts: 64,490
    phew, that would be hard info to find---you'd have to call up Road & Track, speak to the librarian, and ask her if they have reprints of a road test from that year.

    I can tell you, from owning two of them, that they stop pretty darn well for a big barge. I had to put mine "on its toes" a couple of times and it stopped as well as most contemporary sedans do today.

    So if you're asking because yours isn't stopping well, then you're right, it's not.
  • Mr_ShiftrightMr_Shiftright Sonoma, CaliforniaPosts: 64,490
    RE: Benz door locks mysteriously locking --

    Well since you have the panel off, why don't you duplicate the situation where the locks misbehave, and watch what's going on in there?
  • fintailfintail Posts: 47,734
    Is this for a W123 or a W126? I have some period info on the 126 at home I can look through if that's what you need.
  • I did and it looked as if the vacuum element was sucking it down, I did'nt want to unhook the linkage as I think i will try to fix the system properly.
  • Mr_ShiftrightMr_Shiftright Sonoma, CaliforniaPosts: 64,490
    Okay so the vacuum is NOT disconnected. I believe the driver's door has a master vacuum switch (controls all the other doors), so if that is malfunctioning, it could be locking the doors AS IF it thought you were turning the key in the door to the "lock" position?

    Does this make sense? At least it's one possible cause.
  • thanks!
  • My workhorse of a 1982 300TD diesel engine is so keen to work that it won't switch off and I can walk away with the ingnition key in my hand. To get the engine to stop I have to lift the hood and hit a red button marked STOP on the accelerator linkage. Is there a simple way to solve this problem? I really don't mind that the doors have to be locked by pressing down the buttons in the 4 doors
    because the vacuum-operated(?) system is kaput. I though that perhaps (with luck) there might be a rubber vaccum tube located somewhere and I could simply ligature it off so the engine will stop when I turn the ignition key to 'Off'. I'd appreciate any advice,
    Many thanks,
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