Author Topic: New to me 1979 300 SD  (Read 251 times)


  • Newbie
  • Posts: 1
  • W116 Enthusiast
  • Location: DuBuque ia
New to me 1979 300 SD
« on: 16 December 2021, 03:55 AM »
Hey everyone

Just trailered home an Iowa barn find, 1979 300 SD with 140k miles. 

Presenting issues at first glance are 5 inch diameter rust circles on the rear quarter panel, more extensive rust on the bottom of the front door panels and here and there across the body, muffler and exhaust dangling by metal zip ties, somethings stopping the transmission from going into third gear - it might just be a stuck emergency brake- God for bid it needs a new transmission but I can’t imagine that with this engine and only 140,000 miles on it. And the brakes are shot. Driver’s side window will go down but then the glass falls into the door.  Likely tires, shocks, ball joints etc. all need to be replaced as well. Unsure if the heater or AC works.

My mechanic asked me, what did you do now? Which is his standard answer when I drag in some vintage car that needs rescuing.   He prefers working on American cars but he had this up on the lift before I could turn around to take a look.

The good news is that the car is beautiful on the interior, almost mint. I’m planning on restoring this piece by piece.

Looking forward to the wisdom of crowds on this forum!


  • W116 Addict
  • ****
  • Posts: 2,377
  • W116 Enthusiast
  • Location: Vancouver, BC, Canada
Re: New to me 1979 300 SD
« Reply #1 on: 16 December 2021, 09:00 AM »
Welcome here 8)

Yes as you have now discovered, rust is the main bug bear of the 116, they rust like crazy in specific spots, no 2 ways about that.  The OM617 engine is legendary and very stout, so you should not have issues with it.  Regular oil/filter changes is key here and use a good oil like Chevron DELO or Shell Rotella 15W-40.  Many 300SD owners here who can help I'm sure.  Also change coolant ASAP with Zerex G-05 (Valvoline) diluted 50/50 with distilled water.  Vacuum leaks also can really spoil your fun so check any and all vacuum lines and connectors  and replace all suspect ones.

You can also check out mercedessource on youtube.  Kent is a big diesel Benz fan so he has tons of info, but be warned most of his vids are to plug some stupid tool he "invented" to solve an issue he thinks needs solving, so take him with a pinch of  salt.  He does have very good vids on many Benz topics though so well worth a look.

1977 450 SEL 6.9 - Astralsilber


  • Newbie
  • Posts: 6
  • W116 Enthusiast
  • Location: Phoenix, AZ
Re: New to me 1979 300 SD
« Reply #2 on: 16 December 2021, 02:58 PM »
     Congratulations on saving this car.  I daily drive a 1979 300sd and they are great cars. Don't get discouraged when you run into problems.  Just be patient and stay the course and you'll eventually have a car you can be proud of. Good luck.

Jan S

  • Classic
  • **
  • Posts: 169
  • W116 Enthusiast
  • Location: Norway
Re: New to me 1979 300 SD
« Reply #3 on: 16 December 2021, 03:09 PM »
Welcome! Look forward to seeing some pics  :)
1975-mod W116 450 SE with 6.9 engine


  • W116 Addict
  • ****
  • Posts: 1,785
  • MB Enthusiast
  • Location: Fort Collins, Colorado
Re: New to me 1979 300 SD
« Reply #4 on: 17 December 2021, 10:58 AM »
Sounds like you have a good car to start working on. Post some pictures if you can. Start on the safety items (brakes, fuel lines) and work on from there.
'68 250S, '77 6.9 euro, '91 300SE, '98 SL500 '14 CLS550