Just removed the heads from this AJ26 engine, shortly after having installed them. (Back story here: https://www.jaguarforums.com/forum/x...roblem-187450/)

The gaskets used were Cometic MLS gaskets. Both the heads and cylinder decks were verified flat. New OEM head bolts and stock torque procedure were used.

Upon disassembly I found circular indenting, around the bores, but only on the right side cylinder deck and only on the left side head. The corresponding mating surfaces did not have the indents. Depth is a mostly uniform 0.002".






Again, these indents are totally absent from the corresponding mating faces of the right side head and left side deck. I'm not sure why this happened, but to me it seems like it must have been caused by the gaskets. Maybe these two gasket faces were embossed too deeply, or maybe something went wrong with the heat treating. The people at Cometic, so far, have not indicated any agreement with me on these notions. Measuring the bore embossments on the gaskets themselves, the sides corresponding to no indenting measure 0.003" high, and the sides corresponding to the indenting measure 0.012" high. Not sure which is closer to normal, and how much these should have crushed after having been torqued down once.

With the cause of the problem unverified, I don't really want to re-use these gaskets, and will probably just install some composite gaskets.

Has anyone else experienced this problem with the stock 4.2 MLS gaskets, or any other MLS gaskets?