I have a 2003 Discovery HSE that was making a faint clicking and sometimes squeeking kind of sound that I could not pinpoint for the life of me. All of the sudden that sound turned into a loud exhaust leak kind of sound. After dropping the exhause and replacing gaskets it was still there. I finally found this forum and started looking around. I found a post that pointed me to the head gasket. Sure enough that was it. There was a leak between the block and head by cylinder #6.

Thanks to all of your hard work and sharing of information, I was able to save possible thousands of dollars.

 

You'll want to have heads checked for flatness, and be sure that the external hot gas release did not cut a groove in the block. Minor stuff on the head will be taken care of by machine shop when they skim the heads (flatness spec is .002 inch, easy to warp). If block has a groove in that, the block can be decked, more moola.