Mercedes 300D Suggestions

Mr_Shiftright

History may prove me right nonetheless. MB wasn't hi-tech, it was over-tech.

C&D specs are hilarious but I don't think so, with 180 HP driving 3600 lbs.

There are clubs for everything, even Barbie dolls. That doesn't speak to much really.

More to the point...you can buy a used 560SEL for $3000. These are white elephants---let's just say it

fintail

Power from the 560 cars tested by R&T in 86, and Automobile and C&D in 87 are all quoted as 238hp/287tq with a claimed weight of around 3900 in each. The Euro 560 put out 300hp/335tq.

However, in a R&T test of an early US-spec 380SEL in Jan 81 they give it 155hp :sick:

Heck, I can sill get a comparable condition W108 for around 3 grand and a similar fintail or ponton won't exactly break the bank either. It's the fate of almost every old MB sedan - 4 doors + expensive parts = low prices. In those terms, they are all white elephants, no matter their redeeming qualities.

Mr_Shiftright

Yes but people still jump at 300Ds and Sds, and certainly at pontons. People run from 560SELs, and I don't blame them. Everything that went wrong with Mercedes in the 1980s is embodied in that car IMO. No wonder Lexus cut them off at the ankles.

fintail

What did MB do wrong in the 80s? Overpricing?

20 years later Lexus is still no more than a minor contender anywhere but in NA...

Mr_Shiftright

Overpricing, ridiculously complex, outrageous dealer maintenance costs.

The accomplishment of Lexus was their rapid invasion and substantial conquest of Mercedes' American market share.

The LS400 Lexus was a great car right out of the box and their dealer network was superb.

I think it totally freaked Mercedes---it was a shock to them.

As they say, competition is a good thing.

fintail

That sounds more like the 90s to me. The W126 is like a fintail compared to a W140 (and a 140 is like a Model T compared to a W220). The dealer costs are a valid issue, the gigantic network of independent MB specialists proves this.

I wonder if the S still outsells the LS, even with a usual 30-40% price difference.

The LS used the 126 as a benchmark, that's why it was good

But yeah, without competition a new E-class would probably base at 80K.

Mr_Shiftright

I think the Lexus came out in 1990 and put the fear of God into Benz right after that.

The newer Benzes are remarkable cars and certainly are still in the forefront of automotive engineering. They still need to work on quality control, though.

fintail

MB really had a panic then, I think it is directly responsible for some of the half-baked technology seen in some of the cars since. Innovation for the sake of innovation.

corvette

Today there are online clubs and organizations for 126 fans and owners...how about early Lexus?

Yep. LexLS.com, ClubLexus, and Lexus Owners Club. I also happened across a group dedicated to ruining adding forced induction to the SC300... I think that with a twenty-year-old Lexus, the reliability that the brand is renowned for is going to be a question mark.

fintail

The LS one looks promising, model specific. I notice a key note on the main page is PS pump removal - even the hallowed italic L can have problems.

I think a lot of SC300 owners are wannabe Supra TT owners...but that's probably off-topic enough to make Shifty annoyed. :shades:

Mr_Shiftright

It will be interesting to see how the new Benz diesels affect their reputation one way or the other.

The 300D and SD, for all their shortcomings, sold a LOT of diesel cars in a basically hostile diesel passenger car market--the USA.

calaismarie

I've been trying to read through a lot of the suggestions already posted so as not to make anyone repeat themselves, but I'd appreciate some clarification before I go diving in. I'm having a lot of the same issues people here have been posting about: Inconsistent brakes (on any given day they'll go from perfectly fine to COMPLETELY non-reponsive - forcing me to use the parking brake), faulty vacuum lines (doors lock very slowly, car sometimes won't shut off after the key's been removed from the ignition), and super-slow acceleration from low speeds. Do you think ALL of the above could simply be caused by leaks in the vacuum lines (I can't find any presently) or a faulty vacuum pump? or am I dealing with multiple issues?

Mr_Shiftright

They all seem related to vacuum leaks or a bad vacuum pump, yes, definitely.

jameslei

Hello: Yes, I am pretty sure that Mr. Shiftright (see below)
is right. I have washed my hands of the door locks on my 1982 300TD - no big deal to operate them manually.
And I have managed to get the engine to switch off every time by putting a piece of chewing gum where there was a leak in a vacuum line where it popped into something!
Earlier, some well-meaning chap (not on this site) suggested my brake problem - soft brakes and the pedal has to go half way to the floor before anything much happens - was caused by master cylinder problems. I had it replaced and there was no difference at all! I finally got hold of my retired Mecedes-trained mechanic and he thinks that my problem has nothing to do with the master cylinder, the vacuum system or the booster! He says my brakes simply need adjusting! He will do it this Thursday. Mr. Shiftright knows his eggs, so do be guided by him! Good luck!

burdawg

Strange, the car has discs front and rear, nothing to adjust. The pads may be low.

Mr_Shiftright

If the brake pedal goes hard as a rock sometimes it has nothing to do with brake adjustment.

brakeengr

air in the system will cause spongy brakes- make sure to bleed properly.

dotish

I've just gotten my hands on a 123 Manual and looked at the vacuum diagrams for the heater/A/C system. Unbelievable. Has anyone ever successfully ditched the vacuum system and run the blower and A/C compressor with direct electrical connections and separate switches? If so, I'd like to hear about it. If not, you may be able to talk to me about it in a couple of months when I've found an alternate means of cooling my car in the Texas summer.

Mr_Shiftright

Well there are certain bare facts you just have to face here---even if your car just came out of the factory brand new and you switched on the AC, chances are it's not up to a Texas summer under any circumstances. If this is an urgent need, I'd consider some type of "vintage air" aftermarket product. When I overhauled my system, the best I could do was about staying reasonably cool at 85 degrees after running the car on the highway for an hour. But in slow traffic in Texas at 90+, I just don't see this happening with any German AC system from the 70s or early 80s.

Heavy tinting might help. You might also see if you can find a fellow W126 with working AC and take a ride in that car in summer.

calaismarie

i'm pretty amateur, but i understand mechanics and logic pretty well, so it comes quickly. basically i'm saying that i apologize for any repetative or 'dumb' questions, but i totally appreciate the help in understanding. the best place to go is to people with experience!

The brakes went out on me entirely the other day so I took it in for a free brake inspection. They told me the master cylinder's out. I didn't let them do anything with it because I'm not convinced. I know there's a bunch of stuff going on with the vacuum system">link title, so I tested the vacuum pump and unless the gauge itself's bad then the vacuum pump's bad. And that would make the master cylinder test poorly, right? Is it possible the vacuum pump goes in and out of function? Because sometimes the locks and brakes work....other times everything goes out. And that's a pretty risky gamble, so the car's just pent up in the garage right now.

burdawg

If if the vacuum boost to the master cylinder went out, the brakes would still work. You would have to push the pedal harder, but they would still work. Are you saying that the brakes went completely out, pedal to the floor with no braking?

Mr_Shiftright

burdawg's on the scent here.

HARD pedal = bad vacuum booster or vacuum leaks somewhere

SOFT/sinking pedal to floor = master cylinder or brake caliper or brake line issue or air in the lines. (refill, bleed, inspect).

Step on pedal with both feet, press hard. If it keeps sinking and sinking until it hits the floor, that's a bad master cylinder for sure or a big leak somewhere or lotsa air in the lines.

If you press and press and the pedal hits a point and refuses to sink further to the floor, then there's nothing wrong with the hydraulics, it's in the booster.

calaismarie

thanks - a friend bled the lines not long ago - i bet he just wasn't careful enough to get the air out. that makes a lot of sense.

another question - another thing they told me at the shop was that the ball joint had a lot of play, but the parts list they printed out showed a replacement for the control arm. i'm regretting not having the time to ask them to show me exactly what they were seeing. any idea how big of a job that's going to be? It's not show in the 123 Manual (or at least I'm not finding it yet) Especially if I'm already planning to replace the rotors up front there.

Mr_Shiftright

did they tell you the amount of play in the ball joint? More than 1/8th inch is no good but less than that is okay. This shop you go to doesn't do a lot of explaining, do they? :surprise:

calaismarie

all they said was "really really loose" which doesn't sound very good. i had planned on having them give me a lot more information, but i ended up back at the shop super late (actually they held open for 10 minutes for me to get there) because of delayed subways. i didn't feel right about staying and making them explain when i was there so late and didn't even allow them to do any work on it.

Mr_Shiftright

Okay fair enough, but "really loose" is not very precise.

Sometimes things are allowed to be loose---it doesn't matter so much.

Replacing an entire control arm---yeah, that can add up, because you'd probably need to do both sides and then it's one of those "while we're in there" kind of jobs.

I'd ask them to measure the play.

I mean, if it's ready to FALL OUT, sure---that's dangerous.

seh43

I recently purchased an 85 300D project car. Most problems are relatively easy to fix, BUT, the CCU has me stumped. No matter which button I push or which dial I turn, it does absolutely nothing. there is no air entering the cab at any time or speed. I don't even know where to start. Any help would be appreciated!!!

thanks

burdawg

It's nearly impossible to say. You need a FACTORY manual, I'm not sure if the CC manual is separate in 85 like earlier or not. It could any number of problems, vacuum or electrical, in the control panel itself or somewhere else. It doesn't do anything, even when you put it to defrost? Have you checked the main fuse?

seh43

The fuse is ok. When I unplug the harness to the CCU it has power to terminal 7.

I will check the fan motor today and see if I can find a manual.

thanks for the info.

jameslei

Mushy brake problem on my 1982 300TD was not ameliorated by a new master cylinder, or fiddling with the vacuum system. The problem was the badly worn disks
(rotors?) inside the front wheels where the brake pads do their thing; I think they've been on the car since 1982. The bill was $950 Canadian, but now I can come to a stop without prayers!

Many thanks to folks who gave me advice.
James.

seh43

I checked the blower motor and it is bad. I hopefully can find someone to repair it, I wasn't impressed with the price of a new one.

I also ordered a factory service manual, I hope this will solve many issues.

Thanks for the help burdawg.

brakeengr

check the brushes on the motor- if they are worn out, you can fabricate from graphite blocks. Motor itself may be ok.

Mr_Shiftright

That's odd they wouldn't measure the rotors prior to replacing the master cylinder, but...oh well--I had presumed they checked that prior to giving you any further advice....but, what the hell, the car's back to normal, and that's great. Maybe that old master was tired anyway.

seh43

I had a friend check the motor, the brushes were shot. He is building new brushes, and he said everything else looks good.

Again, thanks

jameslei

I'm told that I need new engine mounts on my 1982 300TD. Odd, because I paid a garage to replace them only 2 or 3 years ago. But there was a problem with the engine not switching off recently and there was a whole lot of shaking going on for a while there. My question is:- Is it best to buy mounts (2 of them I think) from Mercedes Benz, or can you suggest an effective and cheaper alternative please?
Also, both of the coil suspension springs at the rear are broken - one quite near the top of the spring and one quite near the bottom. I never noticed until it was pointed out to me, so should I just ignore that fact? Many thanks.]
James.

brillanze

I want to clean the engine of my 1983 SD, as there is some accumulated grime, leaves, dirt, etc. Any suggestions on things to be careful of, watch out for, etc?

Mr_Shiftright

Not much to worry about but of course you have to keep the hose out of electrical boxes.

Diesel grime is pretty nasty stuff. You might consider a stiff brush and Simple Green to loosen all the dirt and grime and then just a brush and warm water to rinse it down. I'm not keen on high-pressure sprays.

waylandchen

i have some issues with my 300d.

when i accelerate, i can hear a rattle through the vents in the front. i fuond out that when i push the shiftknob down alil, but not so much to switch gears, the rattle subsides.

also, my transmission is kinda "loose." (is there a correlation?) when i shift from d 3 2, it feels as if i did not shift gears or the click is very faint. occasionally it feels like a jerk rather than a click. doesnt sound normal though. sometimes when i make a turn, i hear a click from my shift knob. ... anything wrong here?

when my car runs on the road, i can hear some squeaks near the rear tires. its getting quite annoying and the sound mostly originates from the rightside. what is the cause of this? is it repairable?

my air conditioning does not work..the heater (red area) works fine but the cooler (blue area) does not.. i can feel the outside temperature coming in but its not cold on hot days.anyway i can fix this?

the handles that i use to close the doors when im inside the car is coming off. is there anyway to reglue or replace this problem?

im only 20 years old and got this car as a gift. i rarely check up this car for issues. given the age of the car, is there anything that i should check on constantly to ensure proper functioning?

benzsilver

I have 4 issues concerning my MB 300CDT, which i think may be related to poor judgement on my part. 1) i found a pair of keys that i could not identify as to which vehicle they belonged to. I tried it first on my benz as the appeared to be the same as my benz key. First I tried one in the door keyhole. the door did unlock with the found key. then i tried one in the ignition. It two turned on until the alternator and glow plug lights came on. I did not turn it far enough to actuall engage the starter as I was satisfied that the keys that i had found were for the benz. To satisfy my curiosity i went ahead and tried the keys in my 2000 s-10 chevy. to my amasement the key did unlock the s-10 but would not turn on the ignition. i told anita of my discovery. The next day I wanted to drive the benz. It is a 1984 MB 300 CDT. I turned on key to start and the key just hit astop when it got to the start position. I noticed that the glow plug light indicator and alternator light as well as the fuel and battery indicators did not light up. I thought What has happened? to my self. The door buzzer was working and the headlights worked, the signal lights however, did not work. I thought it must be a fuse. On checking the fuse box I discovered that fuse 14 had melted or heated up and blown. I changed the fuse, But that did not have any effect on the problem with the ignition lights or allowing the starter to engage. Also, it seems that the locking mechanism on the steering wheel does not lock the steering wheel in place once the key is removed as in had been locking before trying the found keys. are all these problems related to one event, and where do I start (begin) to isolate or tract down the problem so I can once again enjoy driving my benz. Thank you Bill

Mr_Shiftright

I can tell you that using a "made" key -- that is, one cut from a blank by a machine, often will not work in these cars and can in fact screw up the lock mechanism. If you can find the factory key that you've used for years, that might clear up the problem. If you don't have a factory key, then you may have to replace the entire lock cylinder at the locksmith, or if you have the repair manual, you can order the lock from Benz and do it yourself.

As a long shot, buy some graphite lock lubricant and work the key and see what happens. Sounds like some of the pins in the lock are jammed.

benzsilver

thanks for your response, i shall immediately buy some graphite and work the lock. Question, would this situation have caused fuse 14 to melt or blow? the legend in the fuse box cover for #14 is not totally specific to this area. please comment, Mr Joe, Thnnks, Bill

Mr_Shiftright

Horns, rear defogger, heated seats.

These kind of things could easily be blowing fuses for reasons unrelated to the ignition switch.

burdawg

Especially the heated seats - in a Benz that old the seats are probably pretty worn out, inside and out.

keithmcd

my 87 300D has 504,000 km and i have rebuilt most of it with the exception of the diesel engine which is great (oilchng every4000k). I have a leak in the rad that requires adding coolant a little too often so I am lookin for advise as what to do. I believe this rad has about 200,000km or more on it. I have replaced all the hoses previously. I do have a small oil leak in the front bearing also. Question is - should i try to "treat" the rad with something to block the leak? any suggestions? OR do I need to replace it ...and if replace what's involved? Do i need any other parts than a new rad? How tough is it to replace the front oil seal on the crankshaft? ...any suggestions would be appreciated. thks

Mr_Shiftright

I think the radiator and front crankcase seal are something to be done at the same time. The leak in the crankshaft though might not be fixable, as no doubt your engine is pretty worn out with that much mileage--the crank may be shifting to and fro on the worn bearings. But I'd take a shot at it anyway.

I don't think replacing the seal is all that big a deal (get yourself a workshop manual) but if the wear ring has 2 grooves in it from the seal, then you need to replace the wear ring as well. If there's only one groove, you can buy a special offset seal to cope with that. If there are no grooves, only a polished wear ring, then use the standard seal.

There's no screwing around with a radiator. You need to buy a new one or have that one professionally repaired (if it can be). If you lose coolant one day on the highway, your engine is cooked and your car is a total.

seh43

I have a '85 300D Turbo, (model 123133) which runs great. The windows door locks and climate control, all have there problems, plus the paint work is shot. I have the opportunity to pickup a late '70's 240D less engine and trans, which seems to be in much better shape. the question is, does anyone have experience installing a 5 cyl. turbo into a 240D, (model 123123) body?? I have done engine swaps in American cars but am now retired and would prefer an easy swap.

Mr_Shiftright

I have no idea but I can give you some rough dimensions of the 300 engine:

Length 33.5" back of valve cover to front of fan, Depth 27" top of valve cover to bottom of oil pan, Width 14.5" widest part of oil pan.

Also the 617 oil pan has a front sump so that's something to worry about.

I think for sure you'll be re-wiring the glow plug harness and of course you'll have a different exhaust manifold and routing so no doubt some exhaust welding/bending to do.

hpmctorque

Weren't the body dimensions of the '76-'85 (the W123) 240D and 300D identical?

Mr_Shiftright

Look to be the same yes, although the 300D weighs couple hundred lbs more.

One thing to think about it checking the differential ratios of the two cars. As the Ben diesels progressed through the years, the engines ended up spinning faster at 60 mph---probably due to changes in the differential to give the cars the power they desperately needed.

So my point is that if the differential ratios are radically different, you might end up with a very unpleasant car---if the engine is turning say 4000 rpm at 60 mph.

keithmcd

a) my 300D 1987 has some slack somewhere in the drive train as it often "clunks" when shifting up AND sometimes just changing from reverse to drive. If I am gentle with it the "clunk" is not severe and just seems to be taking up a little slack. What to think? Is there a problem brewing? OR is this "nothing to worry about"?

b) the wires had broken off the thermostat so that the electric auxilliary fan did not work when needed to prevent overheating while idling with AC on in hot conditions. I have had the wires soldered back onto the terminals on the thermostat. I can make the fan run by just bridging across the two wires at the terminals.
BUT how can I TEST to know that the thermostat will now activate the electic fan when needed to prevent overheating?