E36 M42 swap into 1991 318is

[josephb983]

I am looking at swapping the E36 M42 into my 1991 318is. Miles are lower on the E36 engines, and the price is about the same. My question is, what are the differences between these two engines? What do I need to be concerned with?

From my internet searches I was able to find a bit of info, though the topic seems to be rarely discussed.

The E36 has:
1) different belt system (uses 1 belt)
2) knock sensors, which would not be connected after the swap
3) cast internals, vs forged internals on the original E30 engine
4) the air intake is incompatible with E30 hood, and must be swapped from original engine
5) oil pan is also incompatible with E30 and must be swapped.

Are there any other differences?

This will be my first time doing an engine swap without supervision. I did one once before on a different make car, with the direction of a master mechanic. Any advice for a first-timer would be appreciated.

Thanks.

[Jak]

Unless you are swapping an M44 in there I believe your number 2 point is incorrect. M42s have forged crank/rods with cast pistons.

Also I think that the intake is compatible with the E30 hood but the E30 intake is not compatible with the E36 hood. The problem lies with the E36 intake being controlled by the ECU. Thats what makes it incompatible. At least thats what I've heard.

Neither point should have any effect on your swap. Just take the block and head then put all of your E30 parts on it.




Disclaimer: I haven't done this swap so I could be way off.

[josephb983]

So later M42s were also forged then?

[Jak]

yes

[1991 318is]

Search on M42Club.com.

[DipStick]

I did this particular swap about 5 or 6 months ago. For me, the best way was to use the the E36 block, head, and timing components. I swapped over just about everything else, including the E30 valve cover (breather is located wrong for the E30 intake), Intake manifolds, Fuel system, throttle body, pulleys, temp sensors, crank sensor, cam sensor, exhaust manifold, and oil pans / pickup. It was a bit tedious but it gives you a great opprotunity to clean everything up, paint, inspect hard to reach areas, and replace all those trouble-prone cooling and vaccume lines. If you have any questions feel free to post or PM me.
Paul