e36 m42 swap ?

[S.Iliev]

Hello! I need information about e36 m42 engine swap in e21. Can i use m40 oil pan and oil pickup tube? e36 m42 or e30 m40 gearbox and what drive shaft do i need e30 m40 or m10 ?

[jaredmac11]

I want to preface this by saying I am NOT a pro and I do not have a completed swap (yet). There are people here who have great expertise, more than myself. But here's what I'm doing:

I got an e36 M42 off of a 1995 auto. My buddy bailed on an E30 M42 swap so I collected all his M42 and parts for a few hundred.

I am using the e36 M42 engine with the following E30 parts:
- E30 Oil pan (fits the E21 subframe, E36 is much too large)
- E30 oil dip stick (E36 oil dipstick is anchored much higher up and does not fit)
- E30 accessories (E36 accessory brackets are huge, e30 are much slimmer and compact)
- E30 mounting arms (E36 mounting arms are huge and don't mate up well with the subframe)
- POSSIBLY E30 intake if I cannot get the much larger E36 Intake to fit
- E30 Getrag 240 (will be purchasing the 'speedbox' electronic to mechanical converter for speedometer)
- E30 G240 5-speed Driveshaft

The E36 getrag is larger but I hear it is more robust/stronger. It will likely need some tunnel pounding to get in, I know someone has gotten it in a 2002 so it can be done on the e21.
I think thats it.

I think, personally, the E36 M42 is a great engine but I was fortunate to get E30 M42 parts for cheap cheap so I could take parts from each.
Some pros to the e36:
- E36 valves are lighter by 1mm.
- The intake is a pseudo DISA intake which gives a bit more torque. Im interested to research some differences between the motronic versions.
- The early E36 M42 timing case is much more improved over the E30. Its not as good as the late e36 M42, but it is better and less prone to failure (still prone to failure with the plastic timing guide rails)

A few other things Im sure I'm forgetting but that should be the breakdown.

I am crawling at a snails pace at getting my rebuilt E36 M42 in to my E21.

[Tom D]

the oil pan from the E36 pushes the engine too far back and doesn't clear the subframe. the M40 and M42 share the same oil pan and pickup so yes, use either one but be sure its from an E30.

the bell-housing bolt pattern is the same for the M40/42/43/44, M20 and the family of M5x's, so any transmission from one of these engines will work. however i personally prefer the G240 due too its small size. also the six cylinder engines are on a slightly different angle then the M4x so the shifter is not perfect and may require modification.

the E21 came with at least 5 different length driveshafts, the G242 and automatic being the longest of the group. allan, from this forum is currently doing a M42/G242 swap using a E21 automatic shaft and claims it will work just fine. personally i just use E30 318i/G240 shafts and relocate the center bearing mount. because the shafts are adjustable in length and the E21's is not, engine placement is more forgiving.

the M40, M42, M43 and the M44 use the same transmissions, G240 in the E30 and S5D 250G in the E36.

[S.Iliev]

Thanks for the reply.Where i live e30 m42 parts are hard to find and very expensive. I am going to use e30 m40 gearbox, driveshaft, oil pan and maybe diy motor mounts arms. Can i use e36 flywheel or swap it with e30 m40 ? What year e36 DME i need ?

[jaredmac11]

For the DME, I would avoid a 95 DME. In 95, they started scaling up the EWS/Anti theft crap. Im not 100% sure, and I dont wanna make a gamble on it, if you can just swap DME or not.
In 94 they started EWS but its rudimentary and shouldnt be an issue for a swap (just cut the wire). So I would say 92-93 is best, 94 is fine, 95 requires a DME chip flash to remove the EWS2 crap or maybe you can get creative but why make things more complex. Just avoid the year.

I plan on using the G240's flywheel.

[pofo]

For the DME, I would avoid a 95 DME. In 95, they started scaling up the EWS/Anti theft crap. Im not 100% sure, and I dont wanna make a gamble on it, if you can just swap DME or not.
In 94 they started EWS but its rudimentary and shouldnt be an issue for a swap (just cut the wire). So I would say 92-93 is best, 94 is fine, 95 requires a DME chip flash to remove the EWS2 crap or maybe you can get creative but why make things more complex. Just avoid the year.

I plan on using the G240's flywheel.

I just went threw all of this and you can find people selling flashes for the ecu and its not that expencive. I had all of the emmisions turned off and immo disabled and car fired up with out an issue when I got the wiring correct. It's honestly around 10 wires that need to be cut and spliced. Only thing is temp, tach and speedo if your not using factory transmission. For temp I am going to be adding the factory sensor into my car and wiring it into the enging harness.

[jaredmac11]

I wanted a performance chip anyways, so youre right its not a huge deal, but if I had my pick and wanted to keep stock, I'd avoid it.
I think we're on totally different platforms, but I'll have to share my wiring plan with you and see if it should check out. The M42 is simpler than the M54 but we're both on the e36 platform.

[pofo]

I wanted a performance chip anyways, so youre right its not a huge deal, but if I had my pick and wanted to keep stock, I'd avoid it.
I think we're on totally different platforms, but I'll have to share my wiring plan with you and see if it should check out. The M42 is simpler than the M54 but we're both on the e36 platform.

I dont think there is any difference in the wiring to the x20 connector. I would post the wiring I used but photobucket went full retard.

[Somjuan]

Imgur's a good substitute, I'd be interested to see that

[jaredmac11]

The only thing Im not sure about is the O2 sensor heater wiring. Didnt people usually unplug these anyways? Is it necessary?

E21 Pin #	15-pin Color		E36 Pin #	X20 Color	Purpose
1	Brown / Green		23	Brown/Grey	Oil Pressure Switch
3	Green/Black (larger gauge wire)		13	Green/violent	Fuel Pump Power
5	Blue		25	Blue	Alternator Exciter
6	Green/Violet		6	???	Switched Power to O2 sensor heater
8	Green		21	Green	ECU Power
10	Black/Yellow (larger gauge wire)		15	Black/Green	Starter Signal
13	Brown/White		12	Brown/Violet	Coolant Temperature (Gauge)
15	Black		20	Black/Green	Tachometer

[pofo]

The only thing Im not sure about is the O2 sensor heater wiring. Didnt people usually unplug these anyways? Is it necessary?

E21 Pin #	15-pin Color		E36 Pin #	X20 Color	Purpose
1	Brown / Green		23	Brown/Grey	Oil Pressure Switch
3	Green/Black (larger gauge wire)		13	Green/violent	Fuel Pump Power
5	Blue		25	Blue	Alternator Exciter
6	Green/Violet		6	???	Switched Power to O2 sensor heater
8	Green		21	Green	ECU Power
10	Black/Yellow (larger gauge wire)		15	Black/Green	Starter Signal
13	Brown/White		12	Brown/Violet	Coolant Temperature (Gauge)
15	Black		20	Black/Green	Tachometer

Looks about right. I have green/violet to Green/white