m42 vs m44
 

is there a definitive list of the differences between the two (other than the obvioous displacemenet and obd)

M42 has forged internals, M44 has cast internals

A book I have says the reason BMW went to the slightly larger engine was so it would not be so noisy.

I guess the M42 is a little noisier than the M44.

Metric mechanic has a great PDF on their site which is really a brochure for their M42/44 sport and rally engines. They go into great detail about the stock parts of each engine and what they have done to make it better. It's a pretty good read.

I guess i'm more looking for general info...

like, do the heads have the same exhaust manifold port spacing, etc, so a header from either will bolt up...

so on and so forth.

Well, I caught this post at just the right time as I am in the midst of building what I call an M43.

Differences from the ground up:
- oil pan; 1 piece vs 2 piece, oil pick ups in different place, M44 has a nice windage tray

- block: M42 crank is forged - the M44 crank is cast and has a 1mm longer stroke, M44 cylinder walls are 1mm bigger, M44 has oil squirters that shoot up on the bottom of the pistons, m44 craqnk has a pulse wheel mounted to it and the VR sensor is mounted to the rear section of the block

- Timing case: Inner case for M42 has a mount for the front pulse wheel VR sensor. They also have different inner footprints for where it mates to the block, lower outer cases will swap, but not upper. Shape of head is slightly different and the cam sensor is on the intake side of the M44 and exhaust side on the M42

- Oil Filter: housing & filter both different
Pulleys: All different. M42 uses v-belt, M44 uses ribbed, so AC compressor, alternator, and PS pump are all different
- Timing chain: guide system is slightly different, top and bottom guides are different, M42 has a bearing sprocket as a guide in the lower case - replaced with another plastic guide in the M42, mount for one of the guids is a pin and cicrlip on the M42 and a bushing and bolt on the M44. You have to uses the pin and circlip in order to match the upper outer cover from the M42

- Head: M44 = solid lifters, M42 = hydraulic lifters, thermostat provision on the front of the M42 is grooved to accept the older thermostat, the M44 head does not have it and you have to use the plastic housing/thermostat combo. The valve cover breather hose for the M42 is in the front, in the rear for the M44, coolant hose outlet location on the back of the head is different too.

- intake manifold is also completely different, though the bolt patter for it and the exhaust is the same between the two.

Thats all i can think of for now.

J.

I have an M42 and the valve cover breather hose is in the back. I've seen some with it in the front though, I think it's in the front on the older ones, like the engines in E30's.

Nice list, but I found 3 different things on there.

1. The early m42's had v-belt style and the later m42 had ribbed belts.

2. The valve cover breather hose is also in the rear for the later m42.

3. The difference in the intake manifold besides all the plastic pieces on the m44 is that the m42 has DISA and the m44 does not. The throttle bodies are different, the m44 has the ICV mounted on the TB and the m42 has it under the upper intake manifold.

4. The m42 has a vane type air meter and the m44 has a MAF.

Oh yeah. I should have qualified the list by saying that I was comparing it to an M42 from an US e30. It should make a little more sense now.

J.

I know this is old but I am pretty sure the M44 has hydraulic lifters.

As in the engine that replaced the M40 in the late model E36s?

Or are you combining M42 and M44 bits?

Above staement is true. Also M42 has no DISA and M44 has DISA. I'm 100% on this

***ADDED*** The above statement is not true. 1995 during the OBD swap-over some motors have DISA some not. I was wrong.

John Smith

I believe E36 M42s have DISA, according to http://www.europeancarweb.com/tech/t...rs/index.html:


The first M42 generation encompassed the E30 318i, 318is, and 318i convertible. It used three V-belts to drive the alternator, water pump, power steering pump, and air conditioning compressor. The intake manifold incorporated traditional runners, as the ingenious DISA system was still on the drawing board. The E30 M42 timing chain tensioner, tensioning rail, and side guide rail were all improved in the M44, and the new style parts supercede when you order them. There's a good reason for this, too--these parts do wear on high-mileage E30 M42 engines, and can result in timing chain-related engine failures. This is particularly true in engines that have seen severe service.

The second generation M42 was the DISA-equipped, combo V-belt/poly-ribbed belt unit appearing in the E36 318i in 1992. If you want to REALLY split hairs, you can say there is a third generation M42--the one from 01/94-on that uses a single poly-ribbed belt.

My 1995 M42 engine has DISA. And the Oil Filter is M44 style, so they must be interchangeable.
One more for the list (and this is for the masters of the obvious...)
M44 valvetrain has rocker shafts. The pivot for which is hydraulically adjustable.
The M42 has no rockers... valves are actuated directly.
The accessory drive belt is ribbed belt... AC has it's own ribbed belt.
Something else not mentioned, the crank is double weighted on the M42, but not on the M44. see how different they look?
http://img.photobucket.com/albums/v2...i/PB010142.jpg

What kind of crank is that on the right?