Crankshaft/ Harmonic balancer timing mark?

[Unavita]

This past weekend we were at a picnic dominated by a good deal of Mercedes Benz. While there a conversation struck up based around the purpose of the "nipple" on the harmonic balancer of the M117/119 engines. I am told they are/ were not on all Mercedes. One of the older guys, a retired MB mechanic, said that the nipple was intended to make setting ignition timing easier. I couldn't say but I seem to remember that on all of my engines (9 of them) it seems to be correct that the ignition timing at idle with no vacuum coincides with this nipple. But that is from memory. I am hoping that those with more knowledge than me can chime in here and confirm or correct this idea.

Cheers!

 

[Unavita]

To confirm, GSXR, it is indeed so: the nipple on the harmonic balancer IS the mark at which to correctly set the ignition timing?

 

[gsxr]

Great question. I'm not sure. The late M117 and M119 have an EZL with non-adjustable timing. However, there is a crank sensor at the front of the engine which is only used for diagnostic port X11, which was deleted as of 1994 model year. The balancer "nipple" is likely the trigger for this sensor on the M117/M119.

The early M117 and M116 had an adjustable distributor ignition, but that's before my time...

 

[Unavita]

This is the nipple.

 

[a777fan]

I’m confused by your use of the term ‘ignition timing’. Are you referring to the mechanical timing of the engine (crank to cam)? Ignition timing in the 119 can’t be adjusted manually.

 

[gsxr]

This is the nipple.

Picture = 1000 words. I was thinking of something different. I've never seen this nipple on an M119 but I've never owned a .960 variant.

The nipple is used for adjusting the removable TDC indicator/pointer on older engines. See M116 FSM job 03-345. This has nothing to do with ignition timing, only setting the TDC indicator. OM60x diesel engines have the same thing, btw. M119 has a fixed, non-adjustable pointer.