Mercedes 300D Suggestions

Mr_Shiftright

It's a big cannister on the exhaust manifold. Should be easy to spot. If you google "mercedes trap oxidizer" you'll get tons of info on this problem.

As for oil, I'm a complete heretic. I don't think your diesel cars what you put in as long as it is high quality modern oil used in modern cars today. Whether it's this weight or that weight or synthetic or regular probably doesn't mean a darn thing to your engine at this point in its life. If it had variable valve timing or you lived in Alaska, I'd quality what I say, but if you are in a reasonably temperate climate, just use any good oil and forget about it, and change it every 3,000 to 5,000 miles.

Have you EVER adjusted the valves on this engine? If not, you are asking for trouble.

nigel6

I have never adjusted the valves but looking at the previous owners records I see he had them done.I will check them but Ive never done it before. How do I ensure turning the engine the correct way, does the actual cam have to turn clockwise? By turning the engine clockwise using the pulley will that be correct ? Its probably very simple but I am alittle confused as what to turn and which way !!Where should the cam lobe be in relation to the valve for adjustment? Any advice appreciated. Thanks

Mr_Shiftright

You need a special tool to do the adjustment...it looks like a large crow's foot. Other than that, you turn the engine clockwise and adjust each cylinder according to its "firing order". When both cam lobes are not lifting a valve in each cylinder...that is...they are both pointed away from the valves, then you can adjust that cylinder's valves. This is done I THINK cold but you should double-check that.

Valve adjustments should be done as early as every 15,000 and never ever later than 30,000 miles.

If you are going to do this type of repair, you should buy the manuals. They are $$$ but just doing the valve adjustment will buy you about 1/2 the books.

I can't stress enough how important properly adjusted valves are for a Benz diesel.

Also, let's not forget the "Italian Tune-Up"! Highly recommended!

http://articles.mbz.org/engine/diesel/italian/

So, if your Benz diesel doesn't run right---remember

fuel filters

adjust valves

think about replacing injectors (they are only good for about 100,000 miles)

Italian tune up

fintail

I've heard of a product called "Diesel Purge"...is it legit?

Mr_Shiftright

I think so, if it's a really strong injector cleaner....but really, you can't fix damage out of a can....so it depends on the condition of the injectors and whether or not you are trying to revive a worn-out Benz engine with 250,000 miles on it and egg-shaped cylinders and a flat camshaft.

The interesting thing about old Benz diesels is that they will keep running even when really badly worn out. They won't start real well and they won't go very fast, but they will chug along and remain blissfully abused for a long, long time, spewing out filth and reaching 0-60 if you time it with an egg timer.

Old Volvos are a lot like that....I get in one and immediately I find 78 things wrong with it, but it's still running....kind of like an old alcoholic.

nigel6

Valve Adjustment.Do you know what the firing order is on my 1985 300cdt ? The special tool you mentioned, can I modify a regular wrench ? Thanks.

Mr_Shiftright

I need to know the model type (Is this a W123 or W 124).

I suppose you could bend a wrench with heat but you wouldn't get the necessary torque on it. What you need is a crow's foot that locks into a breaker bar or at least a 1/2" drive socket wrench.

nigel6

I understand the vehicle to be a 123 series . I looked in a haynes manual that shows the firing order to be 1 2 4 5 3 ?
Thanks again for all the advice.

Mr_Shiftright

Okay, you have an OM617A engine (write that down). The firing order is stamped right on the valve cover on that engine I believe.

manc

I started reading this forum about three months ago while thinking of buying an early '80's MB Diesel. I have always appreciated Mr. Shiftright's advice. Things such as being realistic, its a hobby car, it is going to cost money on a regular basis, etc.

I have owned about 30 cars over the last 25 years and own 5 now so this car was going to be something mess with and enjoy. So after looking awhile, I went to look at a car close by. It was $500 and the owner only sold to me because I was an adult and knew that the car was going to be an ongoing project. He had turned away a number of teenagers just because he felt that they would've been heartbroken eventually.

At any rate, I bought absolutely the dirtiest car I have ever owned (trucks, land cruisers included) The previous owner lives out in the country on a huge farm with all dirt/mud roads. Also this is not only the first diesel I have owned but also the first automatic transmission-equipped car. The car had handfuls of mud under the fenders and was moss covered. It had been sitting for over a year. I checked everything (thanks again because I knew what to look for). I realize I got a $2500 car meaning as you have explained before, its $500 but needs $2000 more.

The car drove surprisingly well: I drove it 50 miles home in all sorts of driving. The only thing that was irresponsible of me was that the brakes are really soft. The shift selector is a mess but once you find a gear it kicks through the gears very nicely. It doesn't go into park. The P position is where reverse is. The fluid looked fine as well.

I plan on doing most of the work on it myself, but am taking it to the highly recommended MB mechanic down the street to get a full once over, have the transmission problem fixed as well as a few other items to get it up to snuff.

It has very weepy fuel lines but a neighbor and fellow 123 owner (four of us now on my block, crazy!)said that it was a relatively simple fix.

Once I got the car home, I spent two days getting it de-mudded as well as removing the seats and the carpets. The interior is also in very good condition. The seat tracks were, of course, filled with candy, jewelry, eyeglasses, etc. The seats are MBtex and I cleaned them with simple green (dishwashing liquid didn't work)a brush and a bunch of elbow grease. The cream yellow paint (sorry all, I don't know MB paint names or codes yet)looks unbelievable. I just washed it. Can't wait to see what polish and wax do for it.

Sorry for rambling, but I really am grateful for all of the realistic advice and expectations. It has already helped me a bunch. I am usually on BMW 2002 and Land Cruiser sites but have a feeling I will be a here a great deal in the future. Many Thanks, Phil.

By the way, its a 1983 300D TurboDiesel

manc

Hard to believe I could've forgotten anything considering that last rambling email, but I did. My car came with a wind deflector for the sunroof. As a personal taste, I don't like them and especially when they are many years old and beaten up. So I removed it and it had been drilled into the roof. I couldn't believe it! Now I have two holes so what do I do? It is not going to be a show car, so there is not going to be any concours-style welding going on. Should I just caulk them? Any ideas will help. Thanks, Phil.

Mr_Shiftright

Sometimes hardware stores sell these rubber plugs for furniture, electrical, plumbing, etc. I bet if you scrounge around you can find a plug of some sort that will fit in those holes. If you find some black plugs that are a close fit just use a bit of latex black caulk around them and plug 'em in. That should work. Take a bolt with you that neatly fits in the hole so that you have a size reference.

Good luck on your project!

boomchek

"25 cars in 30 years"

You should join us in the CCBA (Chronic Car Buyers Anonymous) discussion.

nigel6

ok. Thanks for all the Advice and suggestions. I fitted new Bosch glow plugs fired up first time. Changed oil and filters, new battery. Not done valves yet but getting to it. Off on a road trip Friday,fingers crossed all will go well. Running great as of today.Even found the time to pull out the drivers seat and repair a broken spring and pad out some squirrel damage !

steveo8

Hi everyone; this is my first post. I just got an '85 300D turbo diesel. I am going to change the filters out this weekend, and I was hoping someone could give me a little step-by-step advice on replacing the primary and secondary fuel filters. I've located the pimary filter under the hood, but am not sure where the secondary one (i.e the little plastic one) is located. Also, is there anything other than simply taking out the old ones and putting in new ones (e.g. filling the new ones with fuel, etc.) that I need to be aware of?

Any help would be appreciated. Thanks in advance!!

Steveo8

Mr_Shiftright

Secondary filter--it's the little white thingie in front of the injection pump. The primary is a spin-off, don't mess with the bolt on top, IIRC....

steveo8

Thanks Mr. Shiftright; any other advice, like filling the filters with clean fuel, etc.?

Thanks again!

Steveo8

zadams

hey,

secondary filter is an inline filter with a steel mesh screen inside (you may already know this). Not necessarily a specific brand and if you ask for a inline fuel filter or secondary filter at any auto parts store, they should have it. it should be located before your lift pump and on the fuel hose line coming from your tank (in other words it should be floating near your engine block on the drivers side not mounted to anything, with rubber fuel hose connected to either end. it may be clear or cloudy white.) it may also not be there at all. in which case you would buy one and install it. repost if this happens for directions on how to install it, but the simplest, not so clean solution is to clamp the aforementioned fuel line with two clamps leaving several inches between clamps, cut in between them, plug the two male ends of the filter into the tubes, and secure it with worm drive hose clamps of a proper diameter range. The amount of air introduced should be so small it won't give you starting problems, but you may have to prime the line. in which case you would pump the primer that is located next to the lift pump on the drivers side front of the engine block. You must fill the new primary filter with fuel before installing it, or you may be priming all day! use clean fuel and do not pour the fuel from the old filter into the new, it could have the filtered particulates in it. good luck.

zak adams
1985 300D turbo
converted to run on veg. oil
185,000 miles
5,000 on WVO

steveo8

Zak:

Thanks for the reply; great information! I appreciate it.

Steveo8

Mr_Shiftright

I always get my filters from the Benz dealer or a Benz-specific web site. I wouldn't recommend buying filters from a chain store for your car. Dealer filters or Benz specialist filters fit the first time. Buying a bogus oil filter is especially bad, since there are different sizes for the diesels depending on production year, models, etc. and chain stores don't have a clue. So you could end up putting in the wrong oil filter (cannister type) and getting ZERO filtration. Not good.

steveo8

Right; I have ordered OEM parts over the net (Bosch), due mostly to the advice read here at the forum. I'll also be putting in a hood pad, which I am hoping cuts down a little on the vibrating hood!

Thanks again!

Steveo8

steveo8

Another pretty basic question.... How difficult is it to change the belts in the '85 300D turbodiesel? I have one belt in particular that has a slight fray, which I'm eager to replace, but have never done this job. If anyone can give me an idea as to the process, or some practical hints, I'd appreciate it.

Steveo8

Mr_Shiftright

It's pretty straightforward as I recall but it would be great if you were on a lift or on ramps. Doing everything from the top could be tedious. You should replace all the belts while you are in there, unless the frayed belt is #1 on the pulleys and the other belts are really good, then just do the first belt.

It's a "nut and bolt" job....grunt work. Always remember to leave just a bit of slack in the belts (1/4" pushing up or down on the belt) and to recheck the belt tension after driving a day or two.

You'll need a pry bar most likely, and box wrenches and or socket wrenches. Don't use open ended wrenches, you'll just skin your knuckles. Get some knocker-loose for the nuts when taking them off and some never-seize for any bolts you remove completely. Be sure your belt buckle doesn't scratch the fender paint and ALWAYS remember the "guillotine effect" of Mercedes grilles in the open position before you bleed to death.

steveo8

again, thanks for your reply!

Steveo8

grandpa1943

I was just gifted a 1985 Mercedes 300D and I'm new to Mercedes ownership as well as diesel. So far my only problem is the door locks -- they are in the unlocked position -- will not lock. I cannot depress the the buttons in to the locking position. Nor can I use the key to lock the passenger side. The only one that works -- with key and pressing down -- is the driver's side. The remaining three do not work. I live in Massachusetts where recently the evening temperatures have hovered in the single digits while the day time temperatures have been in the teens.

Does anyone have an idea as to why I cannot lock the doors?

Any information would be appreciated.

Thanks,
Garndpa1943

grandpa1943

I apologize for the previous post #1492. I just discovered -- by accident -- that the door locks do work. I didn't know that you needed to use the key on the driver's side to lock all the doors.

I think I'm going to need a lot of help.

Thanks,
Granpa1943

Mr_Shiftright

See? you've already fixed something :P

The doors work on vacuum. There are little motors in the doors, at the bottom, if you pop off the door panel (easy job). You should learn to take off the door panels, it's something you will be doing in the future.

brakeengr

My turn signals decided to stop working (1982 300D turbo). The hazards are also not working. Dash light and interior lights are OK.
I checked the fuse- it's ok- the same fuse is for tachometer and turn signals, and tach is ok.
Any idea how I can test and see if the relay is ok or not? Any suggestions what else to look for?
Thanks!

jackson8

I ordered completely new headlights and removed the old ones on my 87 300d but I do not know which wires connect to the new wires. There are 5 different wires on the old and new headlights that are all differnt colors. Does anyone know what color wires are what( which are the headlights, fog lights, high beam)

epicycles

on top of engine there's a 3-way valve operated by throttle - looks like it connects one of two inputs to output? Should the unconnected input leak to atmosphere?

I'm working my way through the vacuum system (without a diagram) before I get someone to look at the gearbox. Car had been slow to change gear, steadily getting worse. I replaced a door actuator now it doesn't like changing gear until very high revs. I've disconnected door locks and headlight adjustment from the vacuum manifold. Problem persists. I'm about to buy a vacuum gauge. Bizarre! :confuse:

epicycles

Vacuum gauge tells me the pump is working ok (23 in Hg). Only loss of vacuum I can detect (by testing lots of combinations) is at the 3-way valve on top of the engine, operated by the throttle. Leak is in the valve itself not the pipes. I haven't a clue what it does! Does anyone know what its normal operation is? What's the safe way to bypass it until I can find a spare? Lastly, what's it called so I can find the spare?
Thanks.

Mr_Shiftright

I think that's the valve that shuts off the fuel isn't it?

If so, those fail all the time.

ryan77300d

I'm almost certain that on an '81 300D, there is a black transmission shift box on top of the valve cover. There are 2 outputs and 1 input vaccuum hose coming in and out of this box. Inside this little black box are two plastic rockers that push down on 2 vaccuum valves which control the shifting of the transmission, depending on what position the throttle is in. The throttle is linked to a plastic cam, which depresses one rocker at a certain throttle position, and both at wide open. These rockers in turn open/close the vaccuum source to the tranny.

Those little rockers have a tendancey to break or wear through, which then causes erratic transmission shifting and the need to floor it to get it to shift. If those are alright on your car, then the actual valves which the rockers actuate are to blame, as you said you've traced the leak to them. Transmission vaccuum valves or shift lever valves would probably be the closest names.

There is no real way to by-pass those things at all. I wouldn't think removing the valves from the equation can be good for the transmission.

-Ryan

epicycles

thanks for replies. Finally found the part as "3/2 Way Vacuum Valve" at several outlets. Next minor problem, I'm in Australia, parts are in US. Non turbo has only one valve.
A bit more reading found "vacuum is about 15 in Hg to 0 at full throttle".
I came to the conclusion (rightly or wrongly) that all the valve is doing is switching between full vacuum (23 in Hg) at closed throttle and adjustable/variable vacuum for open throttle. More open the throttle, lower the vacuum. As Ryan described, my gear change at high revs is because the system thinks I'm driving around with permanently full throttle (0 vacuum).
So, bypass the switch by connecting the pipe with full vacuum directly to the output (to gearbox) pipe and disconnect / close off the other input pipe. Static test, measured normal vacuum. Moving test, changes to 4th at just under 60kph. Didn't test kickdown (didn't expect it to work). Good news is that now I know exactly what the problem is. Other (predictable) result is engine shuts off instantly rather than after a few seconds. Temporary bypass should be ok until I can get hold of the spare (at least a week). I promise not to drive up any steep hills!

steveo8

Hello everyone:

I have been experiencing what seems to be an intermittent electrical issue over the last couple weeks in my 85 300D turbo diesel. My gas guage and temp guage needles in the instrument cluster "jump" sporadically. There is no rhyme or reason as to when they "decide" to do this. For example last night I simply went to the gas station to give up my weekly tithe to the diesel gods, and upon driving home, the symptoms arose. However, for the few days prior, nothing was wrong.

The guages seem to be jumping in unison; it is more apparent when the lights are on. When the problem springs up, the turn signal indicators also blink lightly and quickly, and occasionally the high beam indicator or the "festen seat belt" light will flash. It's like Klaus has been possessed by demons! Lastly, I'll add that it appears to also be affected by the gear chosen; e.g. shifting to drive seems to make the guages jump, while shifting to reverse does not appear to have the same effect. I will also tell you that I recently had the instrument cluster out to fix the odometer. Although I fixed it (yay!), it seems I may have screwed something else up.

I apologize for the vague description; it's just that there does not appear to be any consistency as to when this occurs, and what exaactly is causing it.

Any thoughts are appreciated, (as are suggestions on how to troubleshoot).

Steveo8

Mr_Shiftright

It sounds to me like some wire is grounding unintentionally, since both gas and temp gauge will peak if grounded. Ditto the signals, which are grounded by the directional arm switch. I feel that your recent repair and these demons are related, and that your problem is scientific and not supernatural. (not that old cars can't be possessed, mind you :P )

steveo8

thanks Mr. Shiftwright. Another interesting observation; this morning on the way to work, I noticed that, while nowhere near as dramatic as last night, when I simply engaged the turn signal (left or right, with the same effect), the guages would "tick" just a little in time with the blinking light.

Any specific ideas how to troubleshoot this, i.e. where should I start? With the turn signal arm (which I haven't messed with at all, the round switch at the back of the instrument cluster which apparently gives the cluster power? I'm somewhat at a loss!

Thanks again.

Steveo8

Mr_Shiftright

Gee...it's tough giving electrical advice online---one small error from me and you could fry something. Maybe you could safely start by disconnecting the battery and then loosening the fuse box and seeing if anything bad is going on behind the fuse box---burned wires, loose wires, etc.

Otherwise, I guess you could pull the instrument cluster (which is pretty easy) and wiggle stuff around and see if the problem stops...but you have to be careful about this.

The directional switch isn't too hard to remove...a couple of screws and then you just disconnect a coupler under the steering column...

Really to do this right you should have a wiring diagram and then you can see at what junctions interference is possible among the various circuits that are agitated.

steveo8

Mr. Shiftright:

Definitely; I will absolutely disconnect the battery, and I definitely appreciate the nature of your advice. I am not holding anyone other than myself (and maybe Klaus' demons!) accountable!

Thanks so much for the thoughts. One thing; do you think it's possible the circuit board on the cluster itself is faulty? Maybe I should use the word "likely" in place of "possible?"

Steveo8

Mr_Shiftright

Well it seems too coincidental that you were just in there and then this happens...

steveo8

Just to update; I switched out the guage cluster with a spare, and inspected all the wiring directly behind the cluster and reinstalled. It seems to be working (knock on zebrano wood).

Thanks for the input!

Steveo8

steveo8

I took my 85 300D torbo diesel on its first extended highway trip today. Along the way, I became curious as to the "typical" RPM range for highway speeds (in this case I cruised along typically between 55 and 60 MPH).

I am just curious, as I am not entirely sure the car shifts into its fourth and final gear. The shifts that I can easily perceive (when driving in the "D" gear) happen fairly early, and in reasonably quick succession, then I have a LONG gear, that I don't believe finally shifts into the final gear once up to highway speeds.

Anyway, when cruising along at around 55 MPH, my tach reads 2900-3000 RPM. Is this correct, or should it be somewhat lower, say 2500?

Any thoughts?

Thanks,

Steveo8

fintail

Sounds like my fintail, it shifts into 4th by 30mph or so I think. It is second gear start, right?

ryan77300d

All 300D's were a second gear start, with first only being operable by means of kickdown or 'L'.

Mine shifts the same way, 2 short shifts and then the uber-tall 4th gear. RPM sounds right in the ballpark...probably why everyone says to keep it at 75-80mph maxium for long stretches if you don't want to be replacing a head gasket.

Wouldn't be too worried about the top end gears going awry. From what I understand, shift flares from 1st-2nd or even 2nd-3rd are much more common.

-Ryan

steveo8

Thanks, fintail and ryan, for the insight; I read about the second-gear start somewhere, but frankly forgot about it 'til you mentioned it!

Steveo8

jakequade

Hi I'm a newbie and just bought a 91 300D. I took it into the shop for the front brake light and the mechanic told me that brakes on these cars typically only last 15000 miles. Is that accurate? He said that the front brakes go 3x faster than the rear and that I'll need new rotors and pads. Thanks for your input.

fintail

I don't know if your car needs rotors, but that brake longevity doesn't sound off base. I have yet to see more than 20K miles out of a set of front brakes on a modern MB, especially if it is driven in the city. They also create brake dust like no other car.

brakeengr

Just thought I'd post an update for reference- It was the relay; which is located inside the shifter console. Put in a new relay, and now turn signals and hazard work fine.

dslsimon

Last year I purchased a 1980 Mercedes 300D in Atlantic City and drove it back to Virginia for body parts. I kept the engine and transmission. I would be willing to sell the engine for $400. If you are interested please give me a call @703-898-8952. Good Luck, Simon

ryan77300d

I've posted previously that I placed regular, run of the mill electrical tape on my dash as a temporary measure one afternoon, and couldn't get the marks off my dash.

I tried "Desolve-It", and it didn't do anything, much to my dismay. I've also tried brake cleaner, carb cleaner, industrial grease remover, and every dishsoap imaginable. I work in a paint shop, and it's getting harder and harder to resist bringing home a barrel of Stripe-EZE industrial everything-melter.

Do those dash board arosol paints sold by Dupli-color and such work well enough to be used on an MB interior?

(Nothing at this point has, infact been vapourized off the dash...it still looks great except for the tape marks...pretty durable indeed)

Also, if anyone knows of US/Canadian suppliers of used W123 parts; dashboards more specifically, that'd be great.

Thanks in advance

-Ryan