M104 3.2L I6 swap into W116 280S...how hard...
 

can that be? As Jeremy Clarkson would say....

I had to halt the restoration of my 280S because of money and just recently my E320 Coupe was in an accident totaling it http://forum.w116.org/Smileys/default/sad.gif

I have a mint condition M104 I6 3.2L and the transmission is mint, so is the diff.

Is a swap possible?

The W116 has the M110 right?

The M104 should fit dimensionally, but you would probably need custom brackets for the two engine mounts and the trans mount.

Drive shaft might even need to be custom... :confused:

This might not be easy... :(

The W116 won't have any of the electronics that the M104 needs, surely?

Sounds like a cool project...
 

If you can afford the down time on your 280S then "hard" is how much perseverance you have. You'll have to remove the drivetrain and wiring from both cars and install one of them. It will need some mount and driveshaft fabrication including custom exhaust. The wiring may be the biggest challenge because the W124 loom is mostly continuous and very time consuming to remove. Then you'll have spatial differences to deal with and to decide which electrical features to transplant such as the instrument cluster, climate system, etc. based on compatibility.

Someone local to me just transplanted a 3.2L in a W201. :)

It would certainly be unique and probably improve your fuel economy quite a bit. I would use megasquirt to simplify the whole wiring harness.

The M104 on the W116 mounts should work, but the aluminum arms will probably need some changes made. That would be a little bit of tig welding after taking a sawsall to them to get them sliced in half for welding.

The exhaust will be custom, the W124 front half to the W116 back half.

The driveshaft is definitely custom. The tip of the W116 gets cut off with the front of the W124 grafted into place and then balanced. That or you might get lucky and find the bolt pattern matches up (same diameter circle) so that the shaft stays unmolested. Use the bigger of the two rubber donuts (should be the W124).

Shifter should work with the metal bar's length adjusted a little (maybe).

Tons of electricals moved over (the single hardest part).

Spend a patient, quiet day undoing the wire harness from the body. A minimum of things cross the firewall, but they do so at two points. Your goal is to remove as much wiring as possible but keeping the car running. Label things as you remove them with masking tape and a permament marker. Also take pictures of every connection and write it down in a notebook. Believe me, you're going to forget a few and trip up. Do not use danling tags, they only get ripped off.

-CTH