Here is a pictogram of the thrust assembly.

 

The problem crops up when the front pulley bolt is removed in order to remove the pulley.

 

When the pressure is lost on this stack of parts the oil film will in rare cases, pull the spacer forward

 

and that will allow the rear thrust bearing to fall down onto the crank nose. Then when the bolt is torqued

 

on assembly, the spacer sleeve crushes the bearing.

 

A simple way to avoid this is if the engine is out of the chassis or airframe, sit the engine gently on its flywheel. This will trap the rear bearing against the rear face of the thrust plate, so no problem developes.

So-long as the engine rests on the flywheel the whole time.

 

If the engine must remain in the chassis or airframe during this procedure, attach several bungee straps to the flywheel/flex plate, and pull the flywheel flex plate forward firmly and maintain this tension during the entire procedure.

 

It is also possible for the front bearing to fall off of the sleeve, or for the hard washer on the rear face of the counter weight to fall off as well. The difference here is that this problem can be repaired by removing the pan and inspecting the stack.

 

A dental pick with a 90 degree end works for manipulating the pieces from below.

 

But suppose all has failed and the bearing is off the sleeve. The front cover is off but the thrust plate is still installed. Slide the sleeve out of the way. Take a big goober of axle grease and press it into the opening on one side of the crank. Use a thin wire to center up the rear bearing around the crank. Slide the sleeve back into place. Slip the front bearing on and note the sleeve sticks through the front bearing no more than .003"

or, nil to the naked eye. If there is no protrusion then the rear bearing is properly located. Now tension the bungees on the flywheel to trap the bearing. Check the protrusion again, and if all is well, reassemble the stack, case and pulleys.

 

With the assembly torqued, end play should be .0025" to .0035". Move the shaft by hand to check end play. Not with a giant screw driver. The thrust plate is flexible and will seem to yield an end play measurement even when none exists.

 

Lynn E. Hanover