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  #1  
Old 01-18-2010, 10:36 PM
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New to '83 240D - Where to start?

Hey Everybody,

I just got my hands on an 1983 240D with 240,000ish miles. I say that because the odometer has been broken for 3 years said the previous owner. It's my first Benz and my first diesel. Before, I've had a 1984 Mazda 626 that I drove for 299,997 miles before the shocks came up through the floor. I then had an 1983 Cadillac DeVille with the horrid HT4100 engine that couldn't get past 130,000.

And so now I've got the 240D. It runs, which is nice. But it doesn't have an owner's manual or service manual. So I'm clueless about most things. So here are my questions:

#1. The following wasn't working on the dash: The odometer, the clock and the dash lights. I popped out the dash to fix the odometer and the rheostat. Well, it turns out there is no rheostat. Just a wire connecting the two pins the rheostat connects to. I checked the resistance between the pin and I got zero. So I'm guessing the wire is good. Any clue where to look next?

#2. The door locks are not working. I got a vacuum gauge yesterday to test out the lines, but I have no clue where the vacuum starts. And I know it might just be the fact that the driver's lock doesn't turn, but I haven't had a chance to pop off the interior panel.

#3. What should I be looking at to see if there is anything serious that needs to be fixed right away. The nearest Benz dealer is 50 miles away, and of all of the shops I've called - nobody really has anybody who's worked on them before. I guess pre-OBDII is considered a dinosaur now.

Thanks for the help!

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  #2  
Old 01-19-2010, 11:24 AM
toomany MBZ's Avatar
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Check the bulbs to see if they're still good.
The door locks can be a long investigation. Good luck.
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  #3  
Old 01-19-2010, 12:18 PM
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Change or at least have spare fuel filters in the car. Then search on the problems you see in your car that you want to fix. Drive train is bullet proof & you won't have problems that leave you stranded if you keep the fuel filters changed, glow system working and use good judgement (differs slightly from common sense which isn't common). Acquire a factory service manual for your car. Don't waste your $$ on Chiltons etal.
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  #4  
Old 01-19-2010, 12:42 PM
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The odometer, clock and dash lights may all be separate problems.

The clock should be receiving power always, check that. Beyond that, there is some DIY repair that you can do on the clock (a forum search may find these threads). The odometers can be DIY fixes (plastic gears which you may order online from various sources like odometergears.com), or you can send the unit out to a shop that deals with VDO odometers. The lights may be simply burnt out. The rheostat probably was bypassed because they're dim at full anyways, who'd turn it down?

With any W123, check for rust, thoroughly. Under the floor insulation, under the battery tray, bottoms of the doors etc. There are lots of little nooks and crannies. The jackpoints are an easily visible indicator of rust... Finding more and more rust on my 240D was where I drew the line.

From there, the engine is quite robust. It needs valve adjustments to keep it running well (every 15k miles). To do so requires removing the throttle linkages and valve cover, as well as using two or three bent wrenches (search for valve adjusting wrenches on the forum). Check or change the fluids. Changing the fuel filters is often good given the unknown mileage on it. There's the prefilter (strainer in the tank), which may or may not need anything, the primary filter (clear plastic one in the engine compartment - which has one large air bubble in it, if it has many little bubbles / flowing ones, you probably have an air leak). The large secondary filter is a screw on type that you can find by following the fuel lines. If you fill this with fuel before you install, you won't have to prime the system as much. When you change the filters, check the primer pump (if it has a circular white handle, it's the older type). The older type may not work as well as it should and can be a source of air into your fuel system (not good), as well as cause difficulty when priming the fuel system to the injection pump. The newer versions (like the one sold on fastlane through this site) are cheap, and a nice improvement.

The first step to diagnosing the door system is to figure out the drivers door. From there, get the vacuum diagrams for the car through the FSM. You can block off lines and pull vacuum, to see which part of the system holds vacuum - allowing you to isolate which part needs closer inspection. The trunk also runs off of the vacuum, although, if it's misbehaving, you may have to be careful with locking it (do a search for W123 trunk lock or similar). There have been many innovative ways to open the trunk after the lock will not open. My central locking system was working fine, and the trunk and fuel door simply operated in conjunction with the doors. I never had trouble.

I had an automatic. It was pretty slow (especially when compared to my current vehicle), but not when compared to other 240D's. The manual should be a hair quicker. Fuel mileage varied. Low 20's in city / stop and go is to be expected, with higher 20's on the highway, approaching 30 or slightly higher. They're pretty heavy and not too aerodynamic, so, you can't expect too much. The best I did was about 32MPG on 100% highway (DC beltway, 95, about 55-65mph). If you have fuel leaks, the mileage will be a bit worse (check the return lines! They're the braided ones coming off of the injectors).

Congrats on the new ownership, welcome to the forum, and have fun with your diesel Mercedes!
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1982 240D, sold 9/17/2008
1987 300D Turbo
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  #5  
Old 01-19-2010, 12:43 PM
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Quote:
Originally Posted by QS23 View Post
#1. The following wasn't working on the dash: The odometer, the clock and the dash lights. I popped out the dash to fix the odometer and the rheostat. Well, it turns out there is no rheostat. Just a wire connecting the two pins the rheostat connects to. I checked the resistance between the pin and I got zero. So I'm guessing the wire is good. Any clue where to look next?
Solder a new wire in place of the old wire to see if the lights come back on. I always have my rheostat on high anyways so having one really isn't crucial.

This is a write-up on vacuum leak isolation. A different model than yours, but it will most likely be helpful- http://www.peachparts.com/Wikka/M103VacuumLeak

There are many more DIY articles on this page- http://www.peachparts.com/Wikka/DoItYourSelf


You have come to the right place. No one knows these cars better than the members of this forum.
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  #6  
Old 01-19-2010, 02:11 PM
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If it shuts off when you turn the key, then the vacuum system is in pretty good shape. Many times the vacuum door locks leak enough vacuum that there is not sufficient left to operate the shut off valve on the injection pump.
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  #7  
Old 01-19-2010, 02:33 PM
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W123 Vacuum InterLock Diagram

The link works now, cheers!


Eh...where'd the other post go?
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1982 240D, sold 9/17/2008
1987 300D Turbo
W124.133 - 603.960, 722.317 - Smoke Silver Metallic / Medium Red (702/177), acquired 8/15/2009
262,715 and counting
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  #8  
Old 01-19-2010, 07:24 PM
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Door lock vacuum is one of the yellow lines in the engine bay. There's a few vacuum threads w/ diagrams running around. A gauge is helpful, but a Mity-Vac (or equivalent) is pretty much essential at some point in maintaining and testing individual elements.

If you're willing to risk being locked in, you can try depressing the driver's door lock with the door closed. It should pull the others closed if there's vacuum. You may want to try this with the door open and the latch tripped to the "closed" position, though.

Lock issues are a known problem with replacement of cylinders resulting in mismatched sets. Maybe try a different key or try a different door. Odds are your ignition cylinder has been replaced and the door/engine keys don't match.
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  #9  
Old 01-19-2010, 07:36 PM
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Congratulations on your vehicle. You'll find this forum to be invaluable as you get to know your car. My first MB diesel was also an '83 240D, auto, and I'm into my 3rd year of ownership. It's a great car to work on. As was said earlier, my most immediate benefit came from valve adjustment and fuel filters. New shocks/struts helped a lot in my case (but they were original, I think). You may want to look at the alternator mounting and adjustment hardware as they are a known weakness...just to be sure there is nothing about to fall off. Somebody here in the forum had some good advice to carry a spare voltage regulator in your glove box--I'd second that. When mine failed it left me in a no start situation (in my garage, thankfully).

Search the forum on any thing you have a question about. You'll be amazed at what you find.
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  #10  
Old 01-21-2010, 09:00 PM
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So here's the update.

I replaced the wire that had replaced the rheostat with one of my own and I've got dash lights!!! And while I had the electrical toolkit out, I cleaned up the hazard light got that working as well. And following a DIY on the odometer has now given me a working odometer. And the glovebox door now latches and can be locked as well thanks to some plastic from a broken CD jewel case.

Tomorrow I head over to a family friend's house with a garage so I don't have to pop off the interior panel in my complex's parking lot. So at that point I'll check out the driver's door lock when I replace the interior handle.

But now I've got another two problems that has sprung up: When I took the car to get the oil changed (I wanted somebody to show me what's going on the first time and the local Firestone guys were willing to) and they told me the battery was bad. After a year and a half of the manufacture date. So I got a new battery. Well, last night coming back from the Detroit Auto Show, the battery light came on while I was still an hour's drive away from home. So today after work, I took it to O'Reillys and they said that my new battery was bad and that my alternator was only putting out 30 of the 55 amps it should be putting out.

Now reading some of the threads, some people say that I should replace the voltage regulator to see if that fixes the problem first. Where is the voltage regulator and how hard is it to replace?

The second thing is that after I've replaced the dash cluster, I've started getting wilder swings with the oil pressure after driving for a bit. While I'm moving, the pressure is pinned at 3. But after I stop, It drops down to 2 and once went down to 1.5.

I keep on checking the oil, and the dipstick shows the oil level above the two notches and not dropping at all.
I know that I over-torqued the connector when I was reattaching it. would that cause the problem? Or is there something else that I should be looking for?

Side note: If I should post these in a new thread, just let me know.
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  #11  
Old 01-21-2010, 09:05 PM
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I don't think the oil pressure at idle is of major importance as long as it isn't too low (1.5 bars sounds fine). What is more critical is the pressure when you depress the accelerator, it should be near instantly pegged.

Your oil may be slightly overfilled (if it burns any oil...this may not be an issue for long). Oil changes on these cars are very easy. Just don't strip the drain plug or forget the washer that goes with it (I keep a couple on hand just in case one isn't up to par).
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1982 240D, sold 9/17/2008
1987 300D Turbo
W124.133 - 603.960, 722.317 - Smoke Silver Metallic / Medium Red (702/177), acquired 8/15/2009
262,715 and counting
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  #12  
Old 01-21-2010, 09:08 PM
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Your oil pressure sound normal.
The voltage regulator is that plastic looking round thing that screws to the back of the alternator. You can get that at NAPA.
Sounds like you are making headway. Just remember to have fun.
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  #13  
Old 01-22-2010, 10:27 AM
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Quote:
Originally Posted by phyxer View Post
Your oil pressure sound normal.
The voltage regulator is that plastic looking round thing that screws to the back of the alternator. You can get that at NAPA.
Sounds like you are making headway. Just remember to have fun.
Agreed.
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  #14  
Old 01-22-2010, 10:33 AM
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Oil pressure is fine. It's supposed to peg at 3 bars when you accellerate and will go down to 1.5 when you're sitting at idle. The only probelm is if it doesn't go up to 3 when you accellerate. Oil pressure is a direct feed from the engine up the cable to the switch in the dash so it shouldnt be fluctuating at all while driving.

Voltage regulator is on the back of the alternator. Easy to replace. There's just two or three screws if I remember correctly.

- Peter.
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  #15  
Old 01-23-2010, 05:00 PM
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Ok, another update:

You guys are right, the voltage regulator was really easy to remove. But none of the part stores in the area had any in stock. So it's going to show up on Monday.

Also, where would one go to find the owner's manual and service manual for this car? Since I have neither, All I've been able to do is the stuff that is found on this website?

Also, looking at the back of the clock, I only see one connection. Where is the second?


Last edited by QS23; 01-23-2010 at 05:19 PM. Reason: Fixed my problem with the lock
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