bought my first MB diesel today, now its time to fix all its issues...
 

Ok bought my first mercedes diesel today, well traded for my vw diesel pickup... I know abosolutely nothing about mercedes. the car is a 1980 300sd turbo diesel. Has minimal rust but has many other problems that i need help with.
1. the speedometer works, but above 25mph it makes the loudest vibrating sqealing noise. So suggestions here.
2. the odometer hasnt worked for a while...
3. the tachometer doesnt work...
4. no fan at all on the heater, no matter what buttons i push...
Ok now what are somethings that i should know about that tend to go wrong, or that are good to upgrade. Also what can i do to get the best mpg possible...

if it's a loud unbearable Screeching noise, you'll need to oil/Grease your Speedometer cable.

yes it is a loud unbearable noise so i will oil it and see how that works. My biggest concern is what to check with the heater controls, because i really cant drive it this time of year without defrost...

Check fuses, you may get lucky on fixing the heater fan. There are many posts on here about the fan.
x2 for lube speedo cable
there are posts on here about odometers not working .
There is a lot about tacho's on here, do a search.
Make sure you change the oil regularly & change the fuel filters.
The valve gaps need setting regularly
make sure you always allow it to glow before starting, especially in the cold.
If you plan on using WVO expect trouble. Many of the head ache's on here are related to that.
Read the owners manual.
Change the trans fluid if it hasnt been done lately.
Have fun with your Merc, they are great cars, & will run nearly for ever if you look after them.

The tach is probably the amp.
The heating issue could be a number of things, but that has the dreaded servo unit.
Good luck.

what is the "dreaded servo unit"

Search evil servo, and you'll find plenty of reading. It's a Chrysler thing, and I have no idea why Mercedes would use such a device.

few more questions...
Where can i find replacement gears for the odometer??
Also i havnt tried to start the car cold cold yet, but even if it is still warm it doesnt just fire right up, it cranks over 2 or 3 times before it starts, is this a vacum related issue, or what should i look for???

you should post your location. You might get lucky. A "bored" forum member who wants to pass along his\her knowledge to you might live within 5 miles.

I've got several parts cars.....

I'm not too familar with the SD's but I know in my 85 there's an over volt protection fuse that runs the tach. If the SD's have it might as well take a look.

The servo I believe is made of plastic and lives inside the engine bay. From my searching it appears that the constant heat and freezing causes the unit to crack.

I'm guessing the solution is to replace it or find a manual climate control system. Either way it's a pain in the butt :(

I live in circleville ohio, which is just south of columbus... I will work on putting this in my signature.

The 84 and 85's used a different tach set up.
A friend has the dreaded servo unit, new METAL servo and "new" amp, still doesn't work, so I'm suspecting the "new" amp isn't.

Yeah I thought so :( Worth a comment though.

They make evil metal servos? Are they still evil if they don't crack :P

update...
 

Well i opened the fuse panel and all of the fusses were corroded, and several were actually burnt in half... So after replaceing them all, i now have a blower fan, windshield wipers and spray, intrument cluster lights and operation, and best of all...glowplugs... Now the only thing left is too fix the noise in the spedometer and odometer. And the motor mount... the motor mount came in today, and i got the engine lifted off it, but the mount split in half and im having trouble getting the alenheads off... other than that she runs and drives great

^ Sounds good.

ok... I didn't know they made 'em myself, a friend mentioned that.