350 SD conversion to a 1984 300SD powerplant
 

I have a complete 300SD donor car with a really ugly body. I am considering purchasing a 350SD with a (shocker) blown motor. I believe that it can be done with the donor car that I have. It is currently one of my drivers. The 350SD has an immaculate body. The 300SD has a solid drivetrain but a worn suspension and, as I mentioned before, an ugly body. I believe the vehicle has over 400,000 miles on it. (odo died at about 330,000 before I got it and I have owned it for two years) Given the fact that they are both 126 can I take the parts needed from the 300SD to the 350SD as I go? I appreciate all constructive replies. Thanks.

First, there is no 350 SD that I know of, only the 350 SDL. Is your donor a 300SDL with a 6 cyl 603, or a 300SD with a 5 cyl 617?

Wow, that was fast
 

Hhhm I was pretty sure that there was such a thing as a 350 SD.... I could be wrong. For discussions sake I will assume that we are talking about a 350SDL. (I could have sworn it said SD on the back tag) The donor car is a 5cyl. 1984 300SD.

this is the type of vehicle I am talking about. (of course not the actual one.)

http://austin.craigslist.org/car/663318564.html

There was a W126 350SD, actually.

http://www.stareuropean.com/pictures/233_785.jpg
http://www.stareuropean.com/pictures/234_954.jpg

I think that was the one that was only sold as a 1990 MY? one of those later models either the 350SD or the 350SDL was only sold for one year. the other was sold in 90 & 91.

As far as the conversion goes, its pretty straight forward I think, you will have to ditch alot of the electronics from the 350 motor, It will bolt in with the exception of one of the engine shock mounts, (it will be on the wrong side for your 84 300 sd. If you swap engine and trans together it will work ok.

Problem could arrive when emissions finds out you put an older engine into a newer car, however if that is not a concern, the actually time to do the sway should be about a weekend.


you shouldnt run into many issue, since you have both cars.

Agreed. The 350SD was only offered in 1990. The SDL was offered in both 1990 and 1991

You mean the 350.;)

Actually according to Wikipedia, the 350SD was only available in '91.
http://en.wikipedia.org/wiki/Mercedes-Benz_W126

The Worldpac parts catalog agrees with this statement.

Then of course in 1992 they started calling them 300SD again but put the 350 engine in. That's the one that has baffled me more than any other naming issue.

Might be one of those name recognition things again. Someone looking for a replacement to their then 10 year old 126 300SD would feel more confident buying a new version of their beloved 300SD, instead of a "different" 350SD. Could also be that they changed over to the 140 in 92.

They did the same thing with the 300D 2.5T. Instead of calling it the 250DT like they do in the rest of the world, they were banking on the 123 300D's name reputation in the US to sell more cars. 250D also probably looked too similar to 240D which was the low end model for years. By this time the 190D/E had taken over that position, and they might have thought us stupid Americans would get confused ;)

A 617 in a later sdl is a very attractive car to me.

Heck I even have a spare 617 turbo lurking in my basement garage!

How hard could it be to find a nice 350sdl with a bad motor?:P

Tom W

Yep..........thanks...........no mind left anymore..........:o

So the consensus would be that it would not be a catastrophic failure? Emissions are not a problem in my state as Diesels are emissions exempt. How about the ignition switch? Will the 350 harness hook up to it?