We purchased this 84 300sd turbo diesel a few months ago, our first MB, and love it, but then things started going wrong with it...
1. Wipers stopped... probably wiper motor, but rainex works great for now.
2. Driver and rear passenger windows won't go down.
3. Heater won't turn off, it's blowing HOT air (unbearable since driver window won't go down!)
4. Accelerator is sticking. At first it wouldn't accelerate, and today it stuck while accelerating!

Any advice would be much appreciated!

 

Window issue is either a cracked fuse or corroded fuse. Remove fuse box cover determine from the printed guide which fuse. Regardless of how it looks, replace it! One fuse provides power to l/front and r/rear, another for r/front and l/rear. Wipers probably fuse as well. Throttle can get stuck under improper floor mats or the rods need removed going from the firewall to the throttle and the ball sockets lubed. Just pop off each rod end one at a time and use something like wheel bearing grease on the ball. No need to completely remove the rod, just one end at a time. Less chance of adjustment being messed up!

 

1. If the driver and rear window stopped working at the same time, then I tend to agree, it might be the fuses.
2. If the pedal is getting stuck, then lube up the ball sockets. If you're not handy, get someone to lube them who knows Mercedes cars (especially diesel; there is nothing worse than a mechanic working on a diesel who doesn't know diesels).

Everything carnut said is correct. I had an 84 300SD, they are VERY RELIABLE cars.

Also, how many miles on the car, have you done a valve adjustment ever?

Let us know how it goes!
Tom

 

Thanks for the advice!

The window issue was a fuse. Auto maintenance 101: Check fuses!!!

Still having trouble with the accelerator but haven't really tried to fix it yet.

Our MB has over 211000 miles on it and hope to get many more!

 

For the heater problem consider the monovalve. A failed diaphragm will prevent it from stopping hot water flow. Also and just as likely is the temperature thumb wheel on the A/C controller. If this fails it signals the valve to send hot water into the cabin and you have heat. It is intresting that with a failed wheel, both the a/c and the heater can be running at the same time.

 

You guys are great! I love reading all the great advice in this forum. Husband, Carl, did an oil and filter change last night, also fixed the accelerator issue. Runs great now!

The rod for the accelerator lost the clip that attaches it to a plate. (sorry, don't know the technical terms yet!) For now we are using a paper clip to hold it in until we can order the correct part.

He was amazed at how easy this engine is to work on. Luckily any repairs we've had to do have been minor (knock on wood). Hope it stays that way!

Cathy
'84 300SD 211,000 + miles