Mercedes 300D Suggestions

Mr_Shiftright

No they aren't hard to install.

Yes setting injection pump timing does require some expertise. I guess if you had the 3-volume workshop manuals for the 300D you could take a crack at it.

I still think you need to do a compression test, otherwise you are just guessing here.

if the compression is no good, then all your efforts are in vain.

If compression is good, I'd have the pump professionally set and then replace the injectors. Are you quite sure the valve adjustment is correct?

Did you get a chance in inspect the camshaft lobes for severe wear?

lwoolard

Yes the valves are adjusted correctly. I did inspect the camshaft lobes and they are is good shape. What does it mean if the compression is not good?

lwoolard

How do you do a compression test and what tools do you need?

Mr_Shiftright

You'll need the special gauge for diesels and a remote starter or an assistant to crank the engine.

This might help you:

http://www.goodvibesautos.com/Mercedes-Diesel-Engines.html

Here are more ideas you can try out:

http://www.tdiclub.com/articles/Tune-Up.html

lwoolard

Thanks I quess I know what i'll be doing this weekend. Will I damage anything else by driving the car?

lwoolard

Ok compression good. Next I will be checking the injectors. Now I have another issue. The central locking system. When I lock the driver side all the locks lock. When I unlock the lock, none of them unlock. I know that they are operated by vacuum. They lock fairly quick. They will only lock once when the engine is shut off. The truck and the filler door lock and unlock flawlessly.

Mr_Shiftright

You might check the master vacuum motor in the driver's door or the vacuum reservoir (forgot where that was...firewall? trunk? Looks like a big egg carton.

lydia2

I have had a locking problem and spent much time and $$ to try and find vacuum leaks. I find that if the doors (locks) are opened and locked too many times, some will down lock down. Then if I start up the car and run it for a few minutes, all the locks work again. So maybe that will work for you until you get to the root of the problem.

Mr_Shiftright

The door locks are worked by long levers attached to little vacuum motors at the bottom of the doors. All this leverage can cause problems over time. Sometimes you can get in there and just align or grease these rods, tighten up the vacuum lines, and you get lucky.

lwoolard

Thanks, I will give that a shot. Now how about the inside lights, the instrument lights work fine, they brighten and dim with the little knob. However the lights for the heater controls, and the buttons above the heater controls (back seat light, sunroof, antenna, rear defrost) do not work at all. I replaced all the fuses with new ones when I bought the car and none of them are blown. Any suggestions will be helpful.

ryan77300d

That vacuum reservoir is located in the trunk, as Shifty said, on the sedans. On the coupes, it's in the passenger footwell, IIRC. Anywho, if you're having central locking problems, first thing to check would be the check-valve for the central locking, and this is located under the hood. (these rarely go out). Second place to check would be the master valve, which is inside the driver door and attached to the lock button.

The big giveaway that the problem is the master valve would be that the suction capacity of the car is directly related to the position of the driver lock.

Also, my understanding is that the antenna, sunroof and back seat buttons don't have lights in them. Only the rear defront, when on, lights up. As for the heater controls, are they actually heater controls or the climate controls?

-Ryan

burdawg

That's normal. The manual says that enough vacuum is stored in the resevoir for them to work "several times". Once that is depleted then you need to start it to replenish the resevoir.

lwoolard

Ok on my 1981 300d, at night when I turned on the lights, the instrument cluster behind the steering wheel would light up, the climate control lite up, the temp wheel lite up and the rear light button, sunroof button, antenna button, and rear defrost button (when this button is activated it is brighter) all lite up. Right know when I turn on the headlights the only thing on the inside that lights up is the instrument gage cluster and the gear shifter. Everything else is dark. Any suggestions?

ryan77300d

Taking off the veneer, then the two screws which hold on the climate control cover should reveal the bulbs, may have to pull the whole unit out. (Watch the vacuum lines; they can pull loose)

Worst case you'd have to take out the ash tray, metal ash tray surround, radio, (in that order) then the veneer and climate control. When I did mine, I just took everything out and reached up in behind to change the bulbs, but it's a '77, and as you've stated their's minor differences.

Hope it helps at all

lwoolard

Its hard to believe that all the bulbs are burnt out. Is there anything else.

dieselpro

This model has series glow plugs (like a xmas tree). A problem with one glow plug affects the other three. Make sure that you have a circuit from the #4 glow plug through the #1 glow to ground. also your compression must exceed 300 psi. but the most common prpblem is that the glow plugs do not get hot enough to fire the engine. In responce to this problem Bosch has came out with a kit which includes a new relay that mounts under the hood and more modern parallel wired replacement glow plugs like the cars made after 1981. The difference is night and day in starting ease. This kit was being sold on ebay and most Mercedes dealers also carry it. In my shop in New Orleans this is a job that I do regulary as most of the remaining pre-1981 diesels in stock form are hard to start once the weather cools off in Oct.

dieselpro

I don't know if this is the exact kit that you saw as you state that it was after market but Bosch,who made the system orginally has come out with an upgrade that is well worth the money. My current source for this kit is The Brinson Co in Jefferson La (504)7337326)(Brinsonco.com is I believe their internet site.This kit replaces the loop type series glow plugs with the newer type pencil type perallel wired glow plugs as on cars made after 1981.Cars that would not start at all in summer start after the upgrade. Not only that but since the relay is moved from under the dash, the high amp load between the light switch ind the glow relay (I have had on occasion to completly rewire the circuit between the light sw,the ingition sw,and the glow relay because people grind the starter for long periods trying to start the engine)

brillanze

Don't pull everything out yet--I almost did before I found about the "thingy". The knob that changes the trip odometer--twist it to the right(?) and the lights come up. It's on the left side of the instrument panel.

lwoolard

Tried the "thingy" and only dimmed and brightened the instrument lights, not the others. Is there a ground or something that controls that set of lights? I put a new rheostat in my 1981 and all the lights worked at once. None of them worked before. Could that be the problem on this one? Or if that is bad, the rheostat, would none of them work?

1992300d

I have a significant drain on my batt. Does anyone have wiring diagrams for a 1992 300D? Or can someone tell me if I'm headed down the right direction. I have icolated the drain to two fuses. And have been removing everything that is associated with the two fuses and then checking the volts to see if they jump back up.

brillanze

My front driver's side tire wobbles and shimmies at speeds above 55 on certain road surfaces. I know my ball joints and tie rods need to be replaced, but don't have the $$ to do all at once. I have had the wheels rotated and balanced and the tires are in very good shape. What about wheel bearings? Can I do something cheap to fix the problem now or do I need to bite the bullet and replace the suspension? :confuse:

Mr_Shiftright

Depends how wiped out the front end is---you should at least have the front end checked for safety---if you break a ball at 55 mph joint, you are really screwed....not the car, you personally!

I believe your car carries a steering shock--this is not expensive and you can replace it yourself. This might help your situation, if you feel the shimmy is preceeded by a bump in the road.

lwoolard

Is there anyone that can help on #1787 :confuse:

burdawg

That's an acceptable way to help find your problem. Remember to disable any lights that may be turned on while opening doors, etc so you don't chase your tail.
Another way would be to pull the fuse for the circuit and use an ohmeter on the load side of the circuit to find which branch has the low resistance.
What two fuses seem to be the one's that have an effect?

lydia2

Had the same problem with 83 300D until I changed the bushings in the generator.

brakeengr

similar problem with my 82 300D. It was the glow plugs draining the batt. I replaced a couple of bad glow plugs. Don't remember if I had to replace the relay or not; most likely not.- Just the glow plugs.
good luck.

bbiofuels

Hey I have a 87 300 turbo with an odometer stuck at about 293k. This car runs great other than a few drips of oil. Running b100 I too noticed the injector return lines not holding up. What is the easiest way to get in to the instrument panel to get at the odometer?

Mr_Shiftright

The instrument panel just pries off---it's easy. But detaching everything isn't so easy.

dieselpro

The lighting of the console excluding the lights by the shift knob is done by one bulb and fiber optic conductors to each display. The brightness is still controlled by the Pot in the instument cluster however. The bulb to light all of the switches in the console is located behind the radio in a receptical with a bunch of fiber optics coming off of it.The ac control and shift lighting have their own bulbs.

timingchain

Hi Mr. Shiftright,
I was cruising down the freeway at 75 mph yesterday--I typically do not drive that fast('82 300SD)-- and lost all power. Engine works fine. Transmission does nothing, not even secure the vehicle in Park. If I put it in Drive and rev the engine, I hear a chain-like dragging noise. Vehicle will roll backward or forward in any gear (actually, I've not tried 2nd or 3rd). If it was in Drive and then revved up, it is hard to go back through Reverse until the rpms slow down.
I have the receipt from previous owner showing a factory rebuilt tranny ~45k ago. Fluid on stick is full and appears OK--changed 10k ago.
Recommendations? I found a junk yard with a clean looking used tranny for $750 with a 6 month warranty. To swap it out, do I really have to pull the engine? My manual on CD has no transmission chapter, where can I get information on that? Is there anything else that you suggest I check before I pull out the tranny? I've not had any other problems with the transmission at all and the rest of the car is in pretty good shape. I haven't pulled the pan yet. If I do and it isn't full of metal, what could that mean?
Thanks for the advice.

Mr_Shiftright

Geez, I wonder if this car still has a driveshaft or half-shafts? Have you checked under there for that? No half-shaft, no go.

If the driveshaft/halfshafts are all intact, check for a busted differential (jack up rear of car, spin wheels).

If that's okay, you musta lunched the tranny real good.

Seems odd you'd lose park though..you gotta look under there.

timingchain

Holy cow. The driveshaft coming out of the rear of the tranny is snapped off. I can spin the rear tires--I actually towed it with them on the ground 100 miles--does that mean the differential is OK? What caused that? I guess my next test is to get under there and observe the direction of the driveline/stub when someone shifts. I will keep you updated.
I've never seen a driveline snap before. Is that common?

Mr_Shiftright

Oh yeah it's pretty common. On some Benzes the driveshaft breaks at the front (not good) and I've seen one on a 280SL punch right through the floor.

You're lucky, I've also heard of the driveshaft breaking in the front, falling down, and jamming into a highway rut or pothole at 60 mph. You can guess what happens next.

So, good guess huh?

No reason the diff should be damaged. Of course, you WILL replace all the u-joints and the center support I trust.

Now you know what that clicking/squeaking noise you heard lately, was.

timingchain

Yes, good guess. I'm still surprised. And I'd be really impressed if that clicking/squeaking noise that I was attributing to the driver's side tire area was really coming from the driveline.
So back to the questions. The transmission does appear to go in and out of Drive and Reverse with appropriate outputs now that I've been under there and moved the driveshaft aside to see it. However, I could not get the car into Park. I unhooked the shift linkage and was able to maneuver it manually. The shaft is bent--should it be straight? I would believe that it got hit when the driveshaft snapped on the freeway. Is that the sort of thing I should try to bend and adjust, or buy a new one?
Next: I guess I should avoid a wrecking yard driveline for the same reasons this one went. I haven't removed the exhaust cover yet, but I assume there is a U-joint under there. Do I replace the shaft just to the U-joint, or all the way back to the differential because they're balanced together?
Thanks.

Mr_Shiftright

It's a crap shoot.If you replace one part of the driveshaft shaft and attach it to the other half that's original, you could get vibration. if it vibrates, sometimes you can detach the half-shafts and rotate one of them 180 degrees and try again. Some people say you can put a hose clamp on one of the shaft and move it around, tightening it in different positions, until the shaft balances out. That's pretty clever. Wonder if it works?

There are places that will balance both half-shaft, as they are assembled. That's a sure fire way to get it right.

I really can't say about the park detent. Are you saying you can get into park after removing the shift linkage?

I think I would buy an entire driveshaft from the wrecker and then replace all the u-joints in it. Make sure they DON'T separate the two parts of the shaft until you've marked them with paint!!!

timingchain

As for the shift linkage, I'm going to assume that I couldn't get it into Park only because of the way the rear wheels are jacked up, and I'll recheck it again when everything's lowered.

And I will go driveline shopping as soon as I get this one out. Thanks for all the advice. I am so happy that I don't have a 'lunched' tranny.

timingchain

Hello again. I just got the driveline out of the car and have had a better look at things. What I thought was a broken driveshaft was actually an output shaft (?) coming out of the back of the transmission. It is a male stub with splines that the driveshaft should slip around and then slide into the back of the transmission. The splines are OK, but the end of the stub is worn down.

What should that output shaft look like, and is mine still OK? I took a picture of it, which I can email if someone wants to look at it. As I mentioned before, my manual on CD has no transmission information available. If the shaft is not OK, how far into the tranny does it go? Is that junction between the tranny and driveshaft a common weak point?

For the most part the driveshaft is OK, the only damage it has is a scraped up area where it rode on the exhaust housing while I towed the vehicle. Is it safe to re-use?

The whole flexible coupling area is thrashed, the splines are stripped and the area that slides onto the tranny is wallowed out. I can only guess that the driveshaft started slipping off the output shaft of the transmission, and then started banging around and doing some damage as the parts separated. The center support and u-joints seem fine and show no evidence of being the cause of this. The rear tail housing of the transmission is cracked where it bolts to the rear tranny mount, but I am not sure whether that was caused by the vibration or caused the problem.

Any insight?

brakeengr

The shifter on my 82 300D does not stay locked in PARK when the engine is turned off. With the engine off, and no key in the ignition, I can move it from P to N, R, or D or anywhere. I am afraid of an unintentional roll down.
Any idea what could be the cause, and if it is a simple fix?
Thanks-

Mr_Shiftright

If it actually MOVES into Park but doesn't lock, then I'd guess you have a broken detent in the transmission. You might drop the pan and see if there's anything in there; otherwise it may be accessible from inside the pan without dropping the whole transmission, I just don't remember. Get it on a lift and start there.

brakeengr

Thanks- Yes, it GOES into Park, and stays there fine. But somebody can easily move it out of park without the ignition key, and the car can roll.

brillanze

I think that this car was made before the safety police decided that we couldn't remember to put our cars into park when we parked. As I remember, there were also several incidents where kids got into cars, took them out of park, and the cars rolled off everywhere. Not just a Mercedes thing.

booie1

I think my control module is broken. it would cost me 1000 dollars to replace it. The problem is that two pistons arent firing, so i changed the spark plugs and i checked the coils and they are fine. i think its either the control module or the wires that come from the module. It will cost me 100 dollars for Pep Boys to diagnose it. Is there any advise you can give me any direction, anything i could check or do before i spend my money.

brakeengr

Does the '82 300D have any chassis lubrication points? When I take a sharp left turn, sometimes I can hear a "dry" kinda sound like something needs greasing somewhere.
Any other lubrication type of maintenance that needs to be done?
Thanks....

timingchain

I thought I'd update the problem/fix about my driveshaft separating from the transmission. I replaced the extension housing of the transmission (local Mercedes junkyard in Seattle had them on the shelf...hmm (Aurora Wrecking)), the 3-bolt flange that attaches to it and the flex coupling. There were supposed to be threads on the end of the output shaft to the transmission to hold the 3-bolt flange in place. I cut new threads using a 1" NF die and secured a new nut using high-strength lock-tite. Everything is now back together and works fine.

The question is: what caused the failure? The old flex coupling did not fail. The logical guess was the broken extension housing that the transmission mount attached to caused the transmission to lower and led to all the other problems. Except I replaced that mount this summer and I would have noticed the break, unless it happened since then, and then the question is why did it break?

I wanted to thank you, Mr. Shiftright, for your assistance, and my last question is about that transmission extension housing. Why is it so common to fail--the guy at the junkyard knew exactly the part I needed and they clearly supply them often. The junkyard guy chalked them up to failing flex couplings, but I'm not sure why that would lead to a new extension housing. Any thoughts?

By the way, putting new threads on a 1" shaft that is horizontally mounted while lying on your side underneath a car is not easy, but beats removing the tranny.

Mr_Shiftright

I think it's just old age. You have to remember that as cars age and rack up these high mileages, they will suffer metallurgical distress. They were never built to run 35 years and 300K like some people try to do with cars these days. When I had my 300D, I actually paid someone to carefully inspect all suspension and steering components, and to look for fractures in the control arms, or frame points breaking their welds, etc. It ran up to 278K and then I wasn't so comfortable with that anymore. CV joints started failing and there were various ominous clunks and knocks.

Congrats on tackling a tough problem and defeating it. Very impressive. I don't mean to worry you. I'm sure your car is fine but if you can run her up on a rack and look around for stress-related damage, all the better.

garrafa

I have a 1985 300D (non-turbo European model) that belonged to my mother but has been garaged for about 4-5 years. It was always very well-maintained prior to being idle and had no mechanical issues. I am taking the car to a Mercedes mechanic who has been the only mechanic to work on the vehicle. The car is in great shape and has 103,000 miles. My questions are the following:

1) Can I salvage the vehicle after being idle for so long?
2) What steps will most likely have to be taken in order to get the car up and running and what should I say to the mechanic when I tow it to his shop?
3) With regular and timely maintenance performed on the car can I expect it to be fairly reliable?
4) There is a dent in the grill that has bent the grill from a fender bender but it is largely intact and nice looking. Can this be repaired without having to replace the grill entirely?

I would love to keep the car because it has always been reliable and has fond memories for me. Thank you very much for any help you can give me.

Mr_Shiftright

Sure it can be revived. We don't know what kind of storage it had but the most obvious concerns are the brakes, the battery, the tires and the fuel system.

Diesel tanks can actually grow algae in them, and the fuel itself can decompose, so your mechanic has the lovely job of draining and flushing the fuel tank first off.

Then probably a fresh battery, new fuel filters installed, and crank 'er over (after LOTS of priming, but he knows how to do that).

Once it is running, it's time to check the tires for cracks. if they look okay, the brake system should be flushed and then tested to see if any of the calipers have frozen up. If it starts, goes and stops, then change the oil and filter.

As for the dent, you can take the grill out, get yourself a little ball peen hammer, or better yet a small wooden mallet, and tap away on it until it's straight.

So to summarize (in no particular order)

new battery
check tires, replace as necessary
flush fuel tank
change fuel filters
flush brake system
change engine oil and filter
flush cooling system
change thermostat or at least remove and test.
check all hoses and belts for cracks

That should do it.

garrafa

Thank you very much for your reply. I am taking the vehicle in on Monday for examination and as I don't know much about cars in general, although I have known the mechanic for 22 years, it is good to be armed with knowledge. The vehicle has been in a carport for the past 4-5 years in the Washington DC metro area. The tires do have cracks and so I assume I am going to have to get a new set and it will definitely need a new battery as well. Do you also suspect that I will need to change all the hoses and belts? How much on average do you think it will cost to get the car running and is it unreasonable to expect to get another 150,000 miles from the vehicle? Thank you very much for your valuable and helpful insight and have a good Thanksgiving.

Mr_Shiftright

Looks like about $1,000 should do it--just a ballpark estimate.

Of course don't buy the tires until the thing is running well. You might not have to change belts and hoses. They need to be looked at carefully.

As for how long it will run, that depends on how much $$ you wish to put into it. 250K is a lot of miles.

I ran my old 300D for about $85 a month in repairs and maintenance.

garrafa

That is about what I was thinking in general terms about the price. 250K is alot of miles, but I am hoping I can take it to at least 210K, as it will be mostly urban driving. I have an 1988 Honda Civic 2D HB that has 180,000 miles on it and is what I am currently driving. I read through all the posts and you suggested a regular schedule of fuel filter changes (2x per year), use of diesel fuel additives, and oil changes every 3000 miles. Is there anything else that must be done on a regular basis? Thank you very much for the information. This is a great site!