560 SEL saga continues...

[hbofinger]

Hi all,

Severe power loss after replacement of transmission. The flywheel has been removed to replace the rear seal.

Now we find that the timing, with vacuum removed from the EZL, stands at 20 degrees after top dead center. There are eight bolts holding the flywheel, that means each bolt represents 45 degrees. There are two full crank revolutions per engine cycle, 45/2 = 22.5 The timing is supposed to be 2 degrees BTDC with vacuum removed from the EZL, so it is about 22 degrees off.

My mechanic, though he is willing to revisit the driven plate (proper term for the flywheel on an auto tranny benz), said it is virtually impossible to install incorrectly, because of a notch that would not allow it to be properly bolted down unless lines up correctly. I've got tow mechanics insist that, yes, you can mismount a driven plate, and it needs to be checked.

Can you mismount it, or are we chasing a red herring?

[Frank Reiner]

hb:

Although the locating dowel in the crankshaft, and the corresponding holes in the driven (flex) plates must be matched for the plates to be bolted to the crankshaft, the driven plates can be installed if reversed front-to-back. If that occurred, the ignition timing will be in error. There are timing check holes (alignment holes) in both the plates and in the flange of the starter ring gear carrier. The crankshaft dowel, the check holes in the plates, and the check hole in the flange must lie on on a common line.

[hbofinger]

Originally Posted by Frank Reiner

hb:

Although the locating dowel in the crankshaft, and the corresponding holes in the driven (flex) plates must be matched for the plates to be bolted to the crankshaft, the driven plates can be installed if reversed front-to-back. If that occurred, the ignition timing will be in error. There are timing check holes (alignment holes) in both the plates and in the flange of the starter ring gear carrier. The crankshaft dowel, the check holes in the plates, and the check hole in the flange must lie on on a common line.

Reversed installation is what I was afraid of. Thanks for replying.

[Frank Reiner]

Originally Posted by hbofinger

Reversed installation is what I was afraid of. Thanks for replying.

Although a reversed installation of the driven plates is a possibility, the greater, and more likely possibility is the angular displacement of the ring gear/trigger wheel. The gear/wheel can be assembled to the plates at 120 deg. steps, but the trigger segments are at 90 deg. A mis-assembly in one direction would advance the timing 30 deg., and a mis-assembly in the other direction would retard the timing 30 deg. As soon as the EZL detects "engine running" a small amount of advance is provided from the internal timing mapping; 30 deg. retard minus ~7-8 deg. EZL advance = 22 deg. retarded!

[hbofinger]

Thank you for this insight.