This post is to be ignored as it is a personal rant
My new crank boss arrived so I went ahead and fitted it. It went on tight and square so I was feeling pretty sure that this time it would be permanent!
but to my major disappointment the damper pulley had a wobble in it when i put it all back together.
After a bit of head scratching I decided to clock the crank nose run out. I threaded a stud in the shaft and rolled the motor with the plugs out. To my surprise the bolt did not run true. There was a wobble of .3mm at the end of the crank nose. With the damper pulley in position there is around 1 mm of wobble on the outer pulley face.
How is this possible? One explanation I can come up with is that someone but a block of wood and a bottle jack to the damper pulley to hold it in place while torquing the crank bolt instead of using special tool #7 or whatever its called. (This type of force could bend the crank nose I imagine, not that I'm going to try and bend it back the other way or anything
) The other explanation is that the crank shaft has a crack and it is opening up. This would be bad.
Attaching the adapter flange I made (one in photo) improved things by masking some of the misalignment but the damper pulley still wobbled. (This type of adapter flange in my opinion is good for stubborn key related problems.)
What to do?
I made a tapered shim that sits between the damper pulley and crank boss out of 1mm shim stock by attaching it to block of wood and using an orbital sander to taper it to around 0.5mm. (I blued and test fit it few times to get it sitting right.)
I put it back together and it runs true
Its not an engineering fix as the belts are now misaligned by approx 1mm but it is back together and running fine. More importantly, the gap between the crank sensor and the timing wheel teeth is consistent which means no loss of rpm signal.
On hindsight, when trouble shooting the damper pulley wobble I focused on the fact that the car had had previously had a crank nose key failure and therefore the solution would have be key related. It never occurred to me that the crank nose could also be bent.
Bent crank nose = wobbling damper pulley = use a taper shim.