M44 timing case upgrade for M42

[DesktopDave]

Does anyone know if the late M42 timing chain case requires a differing oil pump?  Any other differences between the early M42 and late M42 (>9/93) lower cases?

I got a PM from another member with M42 Broken Idler Gear Syndrome (BIGS) and needs a bit of help.   I'm under the impression from this thread that a later-model M42 case is the way to go, as it omits the timing chain idler gear but still has the crank sensor mount.  This thread has some good pictures but doesn't have all the info I'd need.

IIRC there's another bolt that differs between the two as well.  I think it's #15 in this diagram, does anyone know for sure?

[pgrandst]

I'm the one who originally asked the question via PM.

All M42 use the same oil pump. The M44 uses a larger capacity oil pump.

Cross referencing the early M42, late M42, and M44, there are differences between them all:

• early M42 and late M42 share same cam sprockets (1121124733811311721887); M44 uses different ones (11361247951)
• early M42 and late M42 share same slide guide between the sprockets (11311721641); M44 uses a different one (11311743046)
• late M42 and M44 (11311743262) have a different chain tensioner guide than the early M42 (11311727342)
• late M42 and M44 (11311734694) have a different chain guide below the crank sprocket than the early M42 (11311721419)
• late M42 and M44 (11311739130) utilize a guide in place of the deflection wheel/gear found on the early M42 (11311727569)
• M44 uses higher capacity oil pump (it's thicker) than early and late M42
• the M44 uses a different crank position sensor than the early and late M42. The mount location is also different. Looking at pictures, M42 chain cases have a mount for the M42 sensor, however the M44 don't. Does anyone with a very early M44 have this mount?

Given I have to replace the chain case, I'm going to get a late M42 style at a minimum to get rid of the deflection wheel. However, if it's not too much hassle, I would love to use the M44 and get the larger oil pump.

Chain case part numbers:
early M42: 11141727191
late M42: 11141739699
M44: 11141739800


Here is a picture of the mount (where 11 fits into 1):


What can I do to use the M44 chain case?

[DesktopDave]

That's some great information there!  Excellent first post IMHO.

I think the main reason the M44 had a higher-capacity oil pump was that it also had piston squirters off the main oil gallery.  The smaller M42 oil pump hasn't caused much trouble from what I've seen...at least if the upper oil pan bolts haven't fallen out.

Personally, I'd stick with the late M42 to keep the front trigger wheel, though the M44 design seems a bit more reliable.  The front-mount crank trigger is vulnerable to rust/scale and physical damage.  Worse, it can lose sync if the harmonic balancer fails

There is also apparently an upgraded oil relief valve in the later motors.

[wazzu70]

The M42 also has the under piston oil squirters.

Good info in this thread. I did not know the M44 had a thicker oil pump gear.

[pgrandst]

If someone has an early M44 (aka 96 or earlier), could they take a quick look to see if they have the necessary casting mount on their timing chain case?