The 1997+ R129 500SL/SL500 which has essentially the same M119 DOHC V8 uses an electric air-pump, rather than the belt-driven air-pump of the pre-1997 500SL's and W124 500E's.

The cost of the "belt-driven air pump" ($900+) vs. an "electric air-pump" ($280) including all the necessary hardware, brackets, and different length serpentine belt ($300-$400 in misc. hardware) for the M119 DOHC V8 engine seems to be a bolt-on replacement.

Moreover, it seems the "belt-driven air pump" eventually goes bad AND gets more expensive, but the "electric" version is in some way simpler and cheaper in the long run.

I would think since the belt-driven air pump had an electric clutch, I could use that signal to "turn-on" the electric air pump replacement, and have a relay controlled 12VDC power source made up.

Any caveats? Any other insights or opinions?

Anyone do this? It would also remove some parasitic pulley-loss.

The 500E's "Check Engine" comes on almost every other month due to the air-pump clutch going bad, and you just can't replace the clutch!

Thanks,
:-) neil
1988 360TE AMG
1993 500E