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. |