Re: Engine tapping when hot.
Ive been thinking same thing. I am a diesel fitter since 1979, and am struggling with this one now for 5 months. I had a set of lifters fitted when I first bought it as that was the obvious possibility. Mechanic told me the donk was spotless inside and assured me he cleaned oil galleries and found nothing. The car has been serviced exclusively by Frost Ford in Darwin since new, and always on time. (I rang the original & only owner prior to purchase, he adored the car and regretted its sale forced apon him because it had lost its business tax advantages, my gain though).
Having said that, I tend to agree with you on a blocked oil supply to one lifter. Is it likely to be evident if I run it w/out valve cover and see oil discharge from rockers?? Never been inside one of these engines but this would be my course of action. Tried engine on 10w30, 15w40 and now 20w50 oil, no difference, worse now if anything.