I'm in the process of putting an OM617 engine in a 380SL. Both the 380 and the 300D donor vehicle are 1985 models.

I've been busy doing lots of research and pulling the engines from both vehicles and getting ready for the swap.

Everything I've found says the swap should work, but the actual data on existing swaps is not very specific. Opinions vary widely but common conjecture is that some combination of mods to the subframe, motor mounts, adding a hood scoop, fabricating spacers to the subframe, remoting the oil filter, changing A/C compressor etc are required, but nothing concrete.

Today I dropped the OM617 into the 380SL for a trial fit and here is what I found.

It fits.... with some qualifications.



Looks pretty good too.

And yes, the hood closes with clearance.



There is plenty of room in the rear, and the radiator and fan fit really nicely in the front.



There is decent clearance for the front of the pan but some potential problems with the rear.




But there is one significant problem, and that is interference between the steering box and the oil filter housing. I had a hunch this was going to be a problem, but fortunately there is a straightforward solution and there is plenty of room on the left side of the engine bay.

The orange arrow shows where the filter is hitting the steering gear and preventing the motor mount from swinging in the direction of the red arrow to allow the engine support arm from dropping into the motor mount.



In this picture the right engine arm is grounded in the motor mount recess, so the net effect is that the engine rear is cocked in the compartment to the left and the transmission is well right in the tunnel. (If you look closely at the first picture, you can see the engine cocked to the left).

I'm using motor mounts from a 1975 300D which so happens to use the same subframe as the R107.

The next step is to jack the engine slightly, pull the oil filter housing and actually secure the left mount in position and bolt up the transmission mount to get final clearances on the pan.

Preliminary assessment shows that the drive shaft appears to be the right length. I don't yet know if the flex disc is the same, but with any luck it will be a simple bolt up.

I'm guessing that there will likely be some minor notching of the rear subframe cross member that will be prudent. (I think the upper oil pan is different between the '75 and my '85 and that is the difference, but won't know until everything is in final position)

When I mocked up the engine on the subframe out of the car, it was obvious that the R4 compressor wouldn't clear the upper control arm mount, so I was already planning on using a Sanden compressor for A/C.

One other thing that doesn't quite fit is the radiator overflow.

I'm also planning on filling the engine and transmission mounts with urethane to make sure there will be no adverse movement of the engine as the mounts age and sag. This should eliminate any clearance issues developing as the mounts age and also eliminate the need for engine shocks at the expense of a little harsher ride. (Fabricating engine shock mounts would be tricky)