Differences between 79' and 80' 300SD - PeachParts Mercedes-Benz Forum

bmonk · #1 03-03-2009, 07:20 PM

I recently bought my 79 300SD as a project car. While it has some issues, including but not limited to, leaking doors(3 new seals installed thus far), trunk and sunroof. Recently discovered that the driver side window motor is dead, none of the dash, or instrument lights work, speakers cut out when switching anything electrical on, just for a moment, and there is some slippage in the transmission. However the body is almost perfect, with no visible rust, or, as far as I can tell, any structural rust, and its "signal red" and has all the chrome. So while the car needs some love, its gorgeous to look at, and the engine seems to be much stronger than my 80 300SD, though I believe thats do to a problem with the 80's turbo charger. The only water damage I have found so far, was inside the passenger door, but thats been mended.

My mission is to part out my 80 300SD to use in my 79. The 80 has quite a bit of water damage, a missing rear corner window, and recently, the rear passenger wheel wobbles like crazy, due to, I'm guessing, bad bearings in the rear axle carrier. However, after running the 80 on 100% high quality bio-diesel for about 6 months, it starts cold, and idles better than many diesel Benz in much "better" condition. In fact it Starts better, idles better, smokes less, and shifts faster and smoother than my 79, which is why I want to swap engines and transmissions. The 80 also seems to steer with much more ease than the 79. I can make a one handed u turn on a dime with my pinky in the 80, but the 79 seems to need some muscle. Oddly enough the steering wheel on the 80 seems quite a bit larger than the 79, which may explain some of that.

So what I am looking for here is some explanation of the technical differences between the two cars, mostly in respect to the engine. There are several visible differences in the air intake area, fuel filter area and turbo charger. Any thoughts, suggestions or data on the subject would be most appreciated. Thanks for reading all this!

I have also found some info suggesting the difference may be that the 80 is a California car, and may have some additional emissions related devices.

babymog · #2 03-03-2009, 07:24 PM

79' and 80', hmm, one foot?

bgkast · #3 03-03-2009, 07:49 PM

The '80 has about 10 more HP than the '79

vstech · #4 03-03-2009, 08:13 PM

a california 116? first I've heard of it.
take some pics and post them here, I gotta see the steering wheel, and engine differences....

bmonk · #5 03-03-2009, 08:30 PM

Well I'll take a photo of the 79, as its out in the garage right now, but the 80 is broke down in another town due to the bad wheel bearing, but check this link out.
http://www.***************/search/product.aspx?sid=chjptrjwf2vlpu55235fg32p&makeid=800016@Mercedes&modelid=1193981@300SD&year=1979&cid=22@Fuel%20%26%20Air%20System&gid=6344@Air%20Intake/Breather%20Hose

the bottom product for $15 is whats on my 80 and goes from the air filter to the top of the valve cover, and as you can see on the part description is says its for California engine. The 79 has a different tube going from the vavle cover to a cross tube from the turbo, or something like that.

vstech · #6 03-03-2009, 08:40 PM

ahh, you're talking about the vent tube... somebody upgraded it to a modern one. the original looked the same as what was on your 80.

bmonk · #7 03-03-2009, 08:49 PM

so which is the modern one? the one going from valve cover to air filter, or the other?

Here is a shot of the 79.

the red cirlces are where the hose connects on my 80

vstech · #8 03-03-2009, 09:04 PM

air filter is the more modern one.
it includes a oil seperator and an oil return line back to the sump. I was not aware that any of the turbo cars didn't have this...
MUCH better setup than having oil vapor dumping on the turbo!

bmonk · #9 03-03-2009, 09:20 PM

so it should be a simple swap then? there are other differences that I'll photograph when I go work on my 80. I had to buy a special pin wrench socket to remove a lock-nut, to get to the rear wheel bearing, so I can replace it, and bring it home, without the wheel falling off.

vstech · #10 03-03-2009, 09:25 PM

ouch. if you've never done any work on a press in bearing with an axle going through it, you're in for a big surprise!
major headache to change that bearing.
better off pulling a control arm off a parts car and swapping that out...

bmonk · #11 03-03-2009, 09:29 PM

Some of the differences make me wonder. Not a big deal, and probably just got taken out by a mechanic, but there is no in-line fuel filter on my 79 either. I know on my 80 it seemed to catch a fair ammount of debris, so I imagine its faily useful.

bmonk · #12 03-03-2009, 09:32 PM

oh... not what I want to hear about the bearing. last thing I want to do is get a parts car for my parts car..... any good reading material I should look at to get an idea of how big a headache? its a topic I have not found covered too well.

vstech · #13 03-03-2009, 09:38 PM

yeah. it's not covered well, because it's NOT a simple repair. I'll see if I can search out some info on the job. you've already discovered it requires special sockets...
cool. a wiki DIY!
enjoy!
http://www.peachparts.com/Wikka/W123RearWheelBearings/show?time=2007-12-03+12%3A41%3A16
I don't know if the 123 is the same as the 116. I hope so!

bmonk · #14 03-03-2009, 09:49 PM

wow nice find! I think you just made this possible. I have the will and time to get it done, plus a friends shop, and almost all those tools, almost.

Thanks very much!!

vstech · #15 03-03-2009, 09:57 PM

Glad it was so easy to find in the search area.
all thanks go to dmorrison! HE's the man!
I just read the discussion thread he did this just to make a writeup!!!
the bearing was not bad to begin with! he just felt like doing a DIY for the rear bearing to figure out how to do it!!!!!
what a trooper!