My Iroc R/T' original Head was replaced with a BRAND NEW Head on Feb. 28, 2001 under Chrysler Extended Warranty for a total repair bill of just over $5,000. Most of which was paid for by the warranty. Now on 9/7/05, with only 18,198 miles on this NEW head it has cracked between the center core plug (Aluminium) and the #3 Spark Plug Hole. It is only seaping, but when I PT'd (Dye Penetrant Tested) it tonight, it proved that my fear was true. The crack wasn't visible at all to the naked eye until I PT'd it.
Prior to removing the rockers from my OLD head, I wrapped the rocker ends with "3M ESPE Express STD Vinyl Polysiloxane Impression Material Putty" to keep the lash adjusters in place and to prevent loosing any disks or other tiny parts. This worked sorta good. The only problem was when I got the rockers installed on the new head and went to remove the putty, it would break up and I had to use a vacuum to suck all the small pieces of putty up and make sure none got into the head passages. Since the head was still off the car, it wasn't much of a problem.