500 SEC engine in 500 SL ?
 

I do have an early (1983) 500 SL (107 model) with a broken engine. However I do have an engine + gearbox of a 500 sec (126 type). Would this engine fit the 500 SL? Especially the engine mounts and the exhaust. Could I do this swap easily while repairing the original engine or is it too complex. Both engines are the same type (117.96x) but the last number of the engine code is different.

Any comments greatly appreciated!

Its the same engine though I believe the SEC is rated at less horse power for some reason. I too have a 500Sl and wondered about a similar swap if (heaven forbid!) it became neccessary.
Mike
1984 Euro 500Sl
1985 380 SE

I put an engine from a 380SEC into a 380SL. This is very similar to what you are doing. It is very do-able.

For sure, you will need to swap the entire oil pan, and the pick-up on the oil pump. You will need to swap the exhaust manifolds.

Depending on the year and engine version, you may need to swap various sensors, emissions stuff, fittings, etc. Worst case, you may need the injection off the SL to be sure you match up with the controls and wiring in the SL.

Engine swaps.
 

I had a 1979 380 SLC euro that I swapped out the 380 and installed a 450 from a 126 chassis. No problem. Someone already mentioned that you wil have to swap the exhaust "headers" (for lack of a better term). Also, the transmissions in the 126 chassis models are typically RT-722.31,2,4,5,x and those for the SL,SLC are RT-722.30x. I dont know that they are interchangable. They may bolt up to any of the appropriate engines but may be dimensionally incorrect for different chassis. This is only a cautionary note, this is seond hand info to me. Good Luck :sun_smile