91 318i M42 swapped with M44 OBD2

[bmw4bmw86]

Hello gang and thanks for having me. I'm a looooong time Bimmer owner/enthusiast however this is my first foray into the world of the 318. So here goes...

I bought a 91 318i sedan with the M42 a few months ago. Nearly 400k on it but plenty of receipts and aside from the usual noisy top end it ran fine. That is until the notorious sump bolts let go. Well, there goes that motor. I ended up with the M44 from a late E36 318i after doing a V8 swap. Now I'm elbow deep into swapping the M44 into my little daily. Yes, I know the M42 is forged and much more appropriate but this is the daily and this is just how it is. The M42 will be rebuilt and eventually back into the car as a poor mans S14. From hours of Google searching it's obvious that no one really ever does this swap. The M44 is cast bottom end and even still the entire world screams for M50/S50 swaps into these cars. I already have a big six car and Id like to keep the 318 as Bavaria intended. I will be running the stock M42 loom and ECU. So here goes with what I know and then with where my concerns are.

I'm aware that the intake and exhaust manifolds along with the sump have to be swapped however I have noticed two interesting things.

 - cam sensor will not fit into the M44 head (it bottoms out before the sensor sits flush)
 - crank sensor is of course on the back of the M44 as opposed to the front of the M42 at the chain case. Just extend the loom and voila?

Alright so now that theres some backdrop I really need the M42 gurus to guide an M20 guy into this murky world of the M42. Being that my E30 is a late model (OBD1) but the motor is a late E36 (OBD2) just what will I be running into electronics wise? Ive already sorted the manifolds, pan, auxiliaries and cooling.

- Is the E36 cam sensor going to have the same plug? (cant tell from pics)
- Will I have any issues with the C101?



I know this post is a bit of a mess but these little motors (of which I have grown to love immensely) are quite different than the M20 and M30 motors that I'm accustomed to. Any help is very VERY appreciated.


Cheers,

         Brandon

[benz-tech]

I got this one.

Cam sensor: if you are running a 91 ecu, use the m42 front timing cover and sensor, they will bolt right up to your m44 head. You will need to run your m42 exh cam sprocket for the magnetic timing pin.  I know the opposite of this works for sure- m42 head,  m44 cover, sensor and intake sprocket - but  you should be ok with the above. I do know the tensioner port has a hole for the front cover (don't know why) but make sure it seals up or your chain will rattle.

Crank sensor: The m44 sensor "should" work. By eye, the gap in teeth of the crank wheel and damper wheels are timed the same.  It will not plug in to the early loom. You will need to make a pigtail that mates the sensor to the loom. The other option, if this doesn't work,  is to use the m42 sensor and make a bracket at the pulley. Or come up with a late m42 timing cover.

There is no need to change anything in your c101 sine the loom is unchanged.

 The temp sensor in the m44 head is a dual temp sensor. Dme 5.2 uses half, the e36 cluster uses the other. You might be able to use the one sensor for both your needs but I don't know the resistance tables to see if that is an option.

Since you're doing something a little different than I have, hopefully this is actually helpful to you.

[bmw4bmw86]

That was actually QUITE helpful. Using the M42 timing cover did't even dawn on me until you mentioned it. I am working on a bracket for the crank sensor. As for the exh cam sprocket that also didn't cross my mind. The M44 has around 145k on it so I may as well do the timing kit anyway.

I'm not too terribly worried about the temp sensor as of yet. I'm hoping that I can run the M42's sensor.

[benz-tech]

If by timing kit you mean rails sprockets etc, I'd just inspect it, mine looked perfect so I ran them. The lightweight and low-friction valvetrain of the m44 puts less load on the chain etc. I'd be more concerned about the head beaing cracked in the spark plug holes- what ultimately led me to using a late m42 head.

[DesktopDave]

Good to hear you've sorted out the oil pan & manifolds. You're using the E30 harness, right? If you use the E30 harness & DME you can avoid all the headaches with Bosch's EWS "tamper protection" system.

As for the temp sensors...IIRC...the E30 sensor/sender pair can be used instead of the single E36 unit. I believe there is a plug where the gauge sender would typically go, so you can use the originals instead of worrying about splitting a single sensor. That CTS is a priority for a healthy-running M42 IMHO.

What's the plan for the serpentine accessories? I seem to recall some issue about the dipstick interfering with them. I don't know much about this either way...I'm just curious about how they'll fit. I have a later model M42 that I'm planning to use just like your M44B19. I thought it could also provide a nice bonus for upgrading to an R134 A/C compressor...or even a home-brew supercharger setup.

I'm a transplanted I6 guy too...I came from an '89 525i M20 with a 5-speed. I've always kept a few M30s around so the little M42 doesn't get lonely. The current herd includes an M20 5 speed 'vert...a 635CSiA...and a pretty zinnoberrot E24 waiting on a dirty M30B34.

[benz-tech]

I don't have a lot of time ATM but: I'm running full DME 5.2 with EWS and chip. NOT a simple swap.

Using all m44 accessories inclu a/c compressor - all e30 lines work with some creativity.  And yes the dipstick required some massaging.

M42 head allows for the 5.2 coolant sensor and I swapped the e30 sensor for the gauge.

I will update my build thread eventually.

[bmw4bmw86]

Thanks for all the input guys. I am already loving this forum.

I've already been through the M44B19. While I'm not thrilled about the cast bottom end it turned out to be a pretty clean motor. I will still be using the E30 M42 harness. In time I intend to pull the M42 apart and rebuild it and possibly swap it back in or find a 2002.

I still have yet to pull the timing cover off of the M42 since apparently I have to pull the M42's exhaust cam sprocket and its cover to go on the M44. I wasn't anticipating to have that issue but it is what it is.

As for the serpentine system it will remain. The donor includes all accessories including the R134 compressor but for now it won't be going on the car, just the P/S and Alt. I'm also waiting on my electric fan and shroud to get here which will also get tied in with the coolant temp sensor. I'm thinking of using the M44 sensor and possibly a relay to operate the fan as opposed to resorting to a probe.

Anyone have a pic of a cam sensor bracket that they've created for this swap?

Since I mentioned the cast rotating assembly can anyone venture as to how stout it is or if I should go ahead and plan on swapping the M44 head back onto the rebuilt M42 block?

[benz-tech]

There are a lot of nice things about the M44 lower end, like piston oil squirters (in the block, not wasting good oil pressure at the rod bearings), lighter rods, lighter slipper-skirt style pistons and a better oil pump/timing chain setup. There are plenty of supercharged ones running around out there with over 200hp and xxx torque that don't have an issue with blowing the cast crank up. The M44 head is the weak point. They are prone to cracking, and having had both the M44 and M42 heads side-by-side I'd guess the M44 head weighs 20-30lbs less. Maybe that's why they crack.

The cooling fan runs off the switch in the radiator - I recommend getting the cooler temp e36 switch - search it, I don't know the p/n off the top of my head. I haven't had a fan clutch in years - just an e36 fan running of the temp switch and since it regularly hits over 100deg here and I've never had it even run hot, I'd bet its pretty adequate. Temp gauge never even moved off center when driving uphill at 112deg with the a/c on in stop and go last year.

I made the E30 a/c lines reach the e36 compressor. its not real pretty but it works. It does require a little bending of the lines.

[bmw4bmw86]

benz-tech -       Are you aware if the crank bolt is torque to yield? Some have said it is a one-torque item.


Can anyone confirm if I will need to swap cam gears if I'm running the M42 cover and sensor? If so I might as well do the guides, etc as well.

[benz-tech]

Never checked the crank bolt torque since I just hit it with a half inch impact- I've been doing this a long time. It's tight but not overly so.
You need the e30 m42 exh cam gear-with a single timing pin- sensor and m42 cover. DME 1.7 wont start without them.  The m44 uses a steel pulse-wheel plate on the intake cam and nothing on the exh cam  iirc. I put both in my engine has both since I was unsure if I could get 5.2 to work. There is no need to pull the head to swap a cam gear, but  having the head checked for cracks and replacing guides isnt a bad idea. If it turns up cracked, the the M42 is a better  choice IMO.

[recordgold]

Im new to this forumn but i actually replaced my m42 e36 with m44. Its actually far easier than led to believe. Ill take pics tomorrow but try to explain all. I used the m44 cam sensor and crank sensor. You have to shave one little piece off the cam sensor plug in to plug into the harness the crank just plugs right in(this might be vice versa,it might be the crank sensor plug you have to shave but either way both will work.i spliced the temp sensor wires together and used just the single m44 head connection, the wires on the m42 and m44 are exact same color. I used my m42 intake manifold. That maybe your one problem.i didnt hook up power steering or ac also... ill prob put power steering back in now that i have the head off again.u could prob get some fittings to make the power steering work tho. I dunno how e30s are but it was all pretty straight forward swap from 95 e36.

[recordgold]

 i felt a very noticeable difference from my m42 to m44. M44 is far better in my opinion besides the plastic thermostat housing (cracked one during installtion and one during water pump replacement.m44 torque is definitely noticeable.the m42 might handle higher revs better but up to 7000 the m44 is creating better power and contrary to popular belief m44 does have forged rods that are lighter than m42.

[dlduke]

Thanks Recordgold. I will try that.