My quest for the "right" old M-B diesel

[Cheaper Jeeper]

Well, so far I have driven

an 82 300D turbo - plenty of power and get up and go - liked it quite a bit.
a 70 300CD non-turbo - it was a bit under powered - but acceptable.
an 83 300SD turbo - again, plenty of power and acceleration - I liked this one just about as well as the 300 D turbo

Here is the odd thing. The 300Ds seem to get about 25-30 mph, but the guy with the SD said he only gets about 17-22 mph. his mechanic told him he probably needs new injectors. The owner also said it smokes a bit on cold starts, so that kind of fits with the mechanic's statement about needing injectors.

So now for a few questions;

1) Do the 300SDs usually get about the same mileage as the 300Ds? The EPA site (www.fueleconomy.gov) shows them as being the same.
2) Will new injectors make that big of a difference in the mpg?
3) Are the MBs like the old IDI Fords - you need to replace the pump when you replace the injectors?
3) How do the price of injectors and pumps for the MBs compare to the ones for the Ford IDIs?
4) Has anybody replaced the steering wheel in one of these old Benzs? Who makes a smaller wheel to replace the truck steering wheel they come with?
5) I expect parts for these old Benzs to be pretty spendy - am I correct in that assumption?

 

[The Warden]

Well, so far I have driven

an 82 300D turbo - plenty of power and get up and go - liked it quite a bit.
a 70 300CD non-turbo - it was a bit under powered - but acceptable.
an 83 300SD turbo - again, plenty of power and acceleration - I liked this one just about as well as the 300 D turbo

Between those three, I'd lean towards the 300SD. It's a full-size S-class car, and you'll be happy for the space someday. My first M-B was a 123 300D, and it was less than a year before I started wishing I had bought an SD instead. The extra room is really nice IMHO. As I said before, I'd shy away from a pre-'81 car due to the climate control...it's problematic, and repairing an early ACC system can easily go into 4 figures (the heater servo valve alone's $800 and is a common failure item). An alternative is a retrofit kit, but you're still looking at $700 plus your time. The ACC on the '81-'85 cars can be pricey to repair as well, but IMHO it's more economical (and far more reliable) than the '77-'80 ACC.

1) Do the 300SDs usually get about the same mileage as the 300Ds? The EPA site (www.fueleconomy.gov) shows them as being the same.

I can't comment with authority since I've never owned one, but I believe that a 126 300SD would be about similar. The car's a bit heavier (3625 lbs for the 123 300SD, as compared to 3515lbs for the 123 turbo), but the weight difference isn't THAT much, and the 126 is considerably more streamlined. I think my buddy with a 126 300SD gets 22 to 23, but he replaced his right foot with a 50 lb lead weight shortly after getting his driver's license.

2) Will new injectors make that big of a difference in the mpg?

If the old ones are all crudded up and the spray pattern's badly affected, yes. However, it IS possible to disassemble these injectors and clean them up and reuse them. They're not meant to be throwaway items like the Stanadyne injectors we see on our IDI's.

3) Are the MBs like the old IDI Fords - you need to replace the pump when you replace the injectors?

No. The M-B fuel system is Bosch and uses an inline injector pump, instead of a rotary Stanadyne pump that the Ford IDI's have. It's far more robust, should last indefinitely, and will be VERY EXPENSIVE to replace if it does go bad. But, I've almost never even heard of one of these pumps going bad, and if it does, it's because of abuse or badly-filtered fuel. M-B injector pumps are not wear items.

3) How do the price of injectors and pumps for the MBs compare to the ones for the Ford IDIs?

For the reasons described above, they're considerably more expensive. IMHO it's worth it, though...I honestly wish it were possible to put a Bosch inline pump and decent injectors in my IDI, just for longevity's sake.

I just checked; MercedesShop sells injectors for just over $50 each, and I can't find a price for the injector pumps...I seem to recall them being somewhere between $800 and $1000, but don't take that as a hard fact.

4) Has anybody replaced the steering wheel in one of these old Benzs? Who makes a smaller wheel to replace the truck steering wheel they come with?

I'm sure it can be done, but I can't think of anyone who's actually done it. I actually like the larger steering wheel, personally...

5) I expect parts for these old Benzs to be pretty spendy - am I correct in that assumption?

Not necessarily. Parts from a dealer (many parts for the 123/126 are still available from the dealer parts counter ) will be expensive, but you can often find parts online for reasonable prices. IMHO a 123 isn't any more expensive to own than a non-Mercedes car of the era, except the diesel-specific parts and some of the front suspension components...although you have to shop a bit more carefully. That said, parts are probably more expensive now than in the past because of the disparity between the U.S. dollar and the Euro.

I usually use MercedesShop or Performance Products. I will say this, though...parts for the 116 300SD I have at the moment are considerably more expensive than 123/126 parts. Not sure why...

 

[BENZIN]

116 was made for 78 81 with the deisel so they had a limited run,but the 116 had a longer run with the gassers 116 mid 70s with the awsome 6.9

 

[The Warden]

116 was made for 78 81 with the deisel so they had a limited run,but the 116 had a longer run with the gassers 116 mid 70s with the awsome 6.9

Actually, it was '78 to '80, not '81. The 116 was replaced with the 126 for the 1981 model year. I believe the 116 replaced the 108 in 1972, with (as you said) the diesel coming into production in '78. The '78 300SD was the first factory turbocharged diesel to be installed in a production car (the 123 300D didn't get the turbo 617 until '81)...

 

[BENZIN]

78 116 was na 79 was the first turbo deisel I think they still made in 81 the 116 300 sd ,but it was a late carry over of the 80 model like mine is a 80 ,but the build date is 79 .

 

[tgatch]

Actually, it was '78 to '80, not '81. The 116 was replaced with the 126 for the 1981 model year. I believe the 116 replaced the 108 in 1972, with (as you said) the diesel coming into production in '78. The '78 300SD was the first factory turbocharged diesel to be installed in a production car (the 123 300D didn't get the turbo 617 until '81)...

Ahh but the 300TD was availiable in 79 as a turbo also.

But for the topic.

I have an 82 300D, if you aren't carrying passengers much it will be plent of room.

The 83 300SD is nice for the room and mileage should be ALMOST identical. I would say that injector nozzles need to be cleaned/replaced, a diesel purge run, check the valve adjustment, and then possibly adjust the timing.

My personal preference would be the W123 300D OR if you can find one a W116 300SD. That body style was the best looking IMHO.

 

[Cheaper Jeeper]

Ahh but the 300TD was availiable in 79 as a turbo also.

But for the topic.

I have an 82 300D, if you aren't carrying passengers much it will be plent of room.

The 83 300SD is nice for the room and mileage should be ALMOST identical. I would say that injector nozzles need to be cleaned/replaced, a diesel purge run, check the valve adjustment, and then possibly adjust the timing.

My personal preference would be the W123 300D OR if you can find one a W116 300SD. That body style was the best looking IMHO.

HMMMN, there is a 78 300SD for sale in my area right now. The pictures look pretty much like a 300D to me - just slightly different marker lights.

I guess it must be bigger though - 'cause it is about the heaviest of them all - nearly 3900 lbs vs 3500-3600 for the rest of them - including the W126.

The 123 or 126 look look like what I really want. Keep in mind, I'm driving a MkII Jetta right now - they all look like battleships compared to my Jetta.

 

[RKOCH]

I got a '80 300 TD wagon that has always got right @ 20 mpg no matter how I drive it. Problem is all the parts to fix anything are more than the car is worth. Lots of new non OEM parts on it now.

 

[tgatch]

The good thing about the 79 -81 300SD and 300TD's is there is no EGR on then engine. HUGE BONUS in my book

 

[Cheaper Jeeper]

The good thing about the 79 -81 300SD and 300TD's is there is no EGR on then engine. HUGE BONUS in my book

Yeah, I hate emissions junk - but most EGRs are easy to disable.

That should apply to an 81 300CD, wouldn't it? I'm trying to arrange a test drive of an 81 that looks to be in MUCH better shape than the 79 I test drove the other day...

BTW, I just bought the tranny, flywheel, clutch, pressure plate, pedal assembly, master cylinders, slave cylinder, and driveline from an 80 240D the other day, so when I'm ready to do the conversion I'll pretty much have everything I need.

 

[tgatch]

81 300CD will be non-Turbo.

Does the driveline include the drivshaft? If not, you'll need one. For the most part you won't need the rear differential.

 

[The Warden]

78 116 was na 79 was the first turbo deisel I think they still made in 81 the 116 300 sd ,but it was a late carry over of the 80 model like mine is a 80 ,but the build date is 79 .

I have seen 1978 300SD's before, and I have yet to see any S-class Mercedes with an n/a diesel. I can't find any reference to one, either...even in Europe (in fact, to the best of my knowledge, the diesel S-class was a U.S. {and Canada} market only vehicle).

Take a look at the engine offerings listed on these sites:
http://www.w116.org/
http://en.wikipedia.org/wiki/Mercedes-Benz_W116

Ahh but the 300TD was availiable in 79 as a turbo also.

Oops, slipped my mind that the TD wagon was offered before the sedan. That said, I think it was offered in late '79 as a 1980 model year car. (based on this article saying that the turbo 300TD began production in September 1979) So, unless all of my info's wrong, the 300SD Turbo still beat the 300TD turbo by 2 years.

HMMMN, there is a 78 300SD for sale in my area right now. The pictures look pretty much like a 300D to me - just slightly different marker lights.

That's a common impression; except for the front end, the exterior of a 116 and a 123 look quite similar. The 123's design was largely based on the 116. Here are some more in-depth pictures of the outside and the inside of a 116...from a distance, they look similar, but there are many differences once you get up close.

IMHO the 116 is a beautiful car; I wish mine was in better shape...

 

[Cheaper Jeeper]

81 300CD will be non-Turbo.

Yes, that is correct, it is a non-turbo. HOWEVER, at $2000 it is half the price ($4000) of the least expensive turbo 300CD I have seen in this area. For that big a price difference I can buy a 300D Turbo motor and put in it and still be about $1500 ahead...

Does the driveline include the drivshaft? If not, you'll need one. For the most part you won't need the rear differential.

Yeah, when I said "driveline" the driveshaft is what I was talking about. Kind of a carryover from the Jeep world - to a Jeeper driveshaft and driveline are synonomous. Is there some other part on these old Benzs (other than the driveshaft) that would fit the description of "driveline"?

 

[tgatch]

I'm a cheaper too. In my head driveline has always transmission to diff. I was just checking to make sure you meant the driveshaft was there.

 

[Meta6981]

I can vouch from experience on the mileage of the 126. I get about 25 mpg and about 400 gallons to the tank on mine. It used to be a lil less like 21-22 range before i replaced the injectors. Since i replaced the injectors it has been running good. Albeit other problems have arisen since then.