What are the differences between the 123 & 126 617 turbo diesel engines?
 

I have both 617.951 (126) & 617.952 (123) turbo diesel engines and am trying to figure out the differences between the engines. They both look basically identical from the outside. I'm planning on rebuilding the 126 type engine and put it in my 300D because at this point it looks like the better of the two engine blocks that I have. This is the one that was completely disassembled by the PO and the same one I started a thread about possibly resleeving the one "bad" cylinder. I discussed the issue of the damage with a mechanic I know and trust and he suggested to me that the cylinder is usable as is and does not need resleeving.
My 123's engine block appears too worn out to use as is because of the ridges at the tops of the bores so I'm going to go ahead and reassemble the 126 type engine.
So at this point I'm wondering what I should look out for between the 2 different engine models.

I can't think of much besides the mounts and the oil pressure sender...

Anybody else?

They are essentially interchangible.

Tom W

I don't have any 126 mounts to compare. I did notice the sender did not fit from the 951 to the 952. I think it was more how the fitting in the oil filter housing is angled. It looks like the filter housings might be different. The 952 engine has a different turbo. I have both types of turbos, each from the different engines.

which comes on which? (seeing that it has been apparently useful to compile seemingly useless obscure knowledge:D)

sveikas.:thumbsup:

617.951 = 300SD

617.952 = 300D

Labas!:thumbsup:

was actually speaking of the turbos..is the A/R on the .951 and the KKK on the .952?

From what I've read, it should be possible, but it will help if you have both cars right next to eachother for the oddball parts that differ (like the oil filter housing, IIRC).

My 952 had the KKK while one of my 951's had the Garret. I have another turbo that's in pieces that was from the other 951 but I haven't looked to see what type it is. I also have another Garret that came from an 85 300D I used to have. It's from a CA emissions model engine so its even different from the other Garret from the 951 engine.
I guess Garret's were used on some engines after Jan '83. Interestingly, my KKK was on an 84 engine.