Hmm, I've though of a loose one, but not an actually cracked one... I'll check that out tomorrow. I did check the flexplate thoroughly before I reinstalled it a year ago, seemd perfectly fine, wasn't old at all yet, but one never knows...
I'll keep you posted,
Max

I'll also check the waterpump, haven't done that yet. Anything before I pull out that engine again, that's a real pain in the ***