m42 swap into 87 325

[hondo898]

I was thinking this was a drop in, but now thinking it may require some modding of the wire harness and or driveshaft, anyone have any info?

[DesktopDave]

I swapped an '89 M20 i motor into an '86 eta sedan.  It was far easier than I thought it would be.  I had to modify the earlier car's wiring harness for the ABS pump (pin 19 on C101 IIRC).  Happily, the round C101 chassis connector was there (the earlier square connector is a lot more work).

You'll need the entire M42 engine harness with the round C101 connector, DME, O2 harness and you might have to extend a plug or two.  The two motors share many things in common but the M42 needs some special ones that the M20 doesn't have, especially the coils, CPS and cam sensors.

I'm not so sure about the driveshaft, the M42 sits farther back than the M20 does.  If you're converting from an auto, you'll definitely need one, as they're far shorter.  You'd also need to pull the tranny start circuit in that case.

[supadave]

I just picked up a 86 325e and thinking about doing the same thing. Already have a fully dressed m42, tranny, wire harness, and ecu.

does anyone have a wire diagram for the early e30's?

[Esprit Aviation]

I have discovered the essential wires needed to run an M42 out of a 1993 e36 automatic while hanging on an engine hoist. It's not much, but may be of some help. What year is your M42 and do you have all sensors, ecu, etc?

[hondo898]

I have a full engine/tranny with all the wiring. So should go smoothly with a few mods

[wazzu70]

I swapped a 91 M20 to a M42. i used the M42 engine harness to c101 and the M42 c101 to DME harness. Made things much easier to have a proper setup instead of a hacked one.

If you use the G240 you also need the M42 prop shaft as its about 75mm longer from an eyeball guess.