82' 300D rookie
 

Hello all. I am new to merecedes and this forum. A couple of days ago I traded my volvo wagon for a 1982 Mercedes 300d. The body is in good shape and the motor seems to be sound but it has spent the better part of the past 4 years, parked. I will be going over the engine the next few weeks and tuning things up a bit.
As it is right now, it's slow to start and seems to idle pretty rough. When I give it more fuel, the rattle evens out a bit. It is slow on the take off and the pedal is hard to press, but once up to speed its fast. The shift into second is a little hard when gunning it ( will even squeak the tires ) and the front drivers side and rear passenger side windows do not roll down. Also, the car won't shut off when the ignition is off. I use the lever under the hood.
Could the hard shift, windows, and no shut off be from a vacuum leak in one location and does anybody know where to start looking? I am going to replace the filters, adjust the valves, tighten up the linkage, test the glow plugs and what ever else you all recommend. I pretty happy to have this car and will be converting it to wvo this coming spring.

I appreciate any help or suggestions you all may have and hope that some day I will be able to contribute to the forum as well.

Buy a mighty vac and find a schematic to the vacuum lines to start troubleshooting. Sounds like you got a vacuum issue.


Here is the manual you need, courtesy - Mercedes Benz.

look under w123

Thank you for the reply and advice. The link you attached does not work, do you know the address for the manual?

I hope you have new fuel filters. 4 yrs worth of gunk in the old ones is not a good thing.

Welcome to the forum !!

Hard shift is low vacuum. Simplest troubleshooting procedure is to unplug the door/trunk system under the hood, plug the place it was plugged into with a golf tee and see if the engine shuts off. That line exiting thru the firewall is yellow. If engine shuts off, leak is in that yellow door/trunk system. Then do the same thing with the green line--climate control system. If unplugging both of those systems don't solve the problem, the leak is under the hood.

Lubricate the accelerator linkage balls. Don't adjust it much. It's intended to have movement in the pedal before you get increased engine speed.

Could be a bad fuse on the windows or dirty switches.

Thank you. I unplugged the two yellow lines and covered the holes and it shut off. So now I need to find where all those lines go. Are there any diagrams around that show the door/trunk system? Do you guys recommend a certain manual and set of tools for this car? Right now I
have nothing as far as a manual goes. I have plenty of tools but none specific to the car. Thanks again. Also, where is the fuse box on this puppy? Thanks

Fuse box is under the hood on the left near the brake booster. Vacuum diagrams are on here. One way to test the door lock system is to hook it back up start the engine so you have good vacuum, get in the car and lock and unlock the driver's door. Observe the other doors to see if they lock or if there is hesitation. If there is, there's probably a leak in the vacuum pod on that door. Eventually you'll need a Mity Vac to test things. Those yellow lines run to the driver's door and then under the floor mats.

try again:

startekinfo

Go here and select Star Tekinfo

then

MB Workshop Resources

Then scroll down till you get to Model 123 Service Library and open it. Schematic should be in there somewhere.

There are a couple stickies for vacuum diagrams. I customized one for the coupe that'll be similar. Do an advanced search for the word "definitive" by yak.

Nice, Thank you.

The Vacuum leak issue can also be related to your no shut off issue.

Pull the Brown Tubing off of the Rear of your Fuel Injection Pump and check to see if there is Motor Oil in it. If so the Diaphragm of the Vacuum Shutoff is starting to go South.

Attach a separate Hose to it and while the Engine is running and either simply suck on it or use the Mighty Vac (hand held Vacuum Tester that you can pump) and see if the Engine will shut off. If it does not shut off you clearly need a new Vacuum Shutoff.

There is also another Vacuum Shutoff valve located on the Steering Colum Lock. You will see another mostly Brown Tubing (I do not remember which brown tubing has the stripe on it) going through the Fire Wall. It will be the one that connects to the other Vacuum Lines.

While the Windows not moving can also be an issue with the Switches (they can be taken apart and the Contact Points cleaned/scraped).
The Door Panel can be removed and you can connect the Window Motor drect to a Battery to see if it works.
Unlike your Starter Motor the Window Motors do not use a ground to the Chassis as part of the circuit.
Connecting the Window Motor Wires to a Batter and the Window will go one way. Swapping the position of the Wires will make it go another way.

Check your glow plugs, properly operating ones should provide easy starts, if you have even decent compression.

Thanks for the reply. When I disconnect the yellow line on the yellow splitter that goes through the firewall and plug it, the car shuts off. Would this rule out the Vacuum shutoff? I checked for oil in the brown line and did not see any. Could the windows also be related to the yellow line that has the leak? Thank you for your help.

Yep, I am going to replace the glow plugs. The battery needs to be replaced as well. I have to jump the car with my F350 diesel and it takes a long time for it to fire. Once the car is warmed up, it turns right over. The start may be on its way out as well. After cranking for a bit, it makes a funny noise while turning off ( at least I think its the starter making the noise ). Do you recommend a certain brand of glow plugs?

Windows are electric. Not connected to vacuum.

Thank you all for the replies. I really appreciate it. While I'm at it, I might as well ask you all what fluids you use. I am going to be giving the car an oil change, flushing the tranny, flushing the coolant, and the break lines. I have no manual ( will pick up a book asap ), but usually these forums have the best advice. Also, what glow plugs? And any other suggestions for a car that I have no history on and likely sat for most of the past 4 years. Should I add anything to the diesel tank? The filler cap was dang near rusted on. Fortunately, the rust was just in one little spot but I'm sure the fuel gathered a little water over the years. Thanks again.

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