Funny you should mention that. I did the same one time
and it worked for about a week. This time they changed
out the chain, tensioner, rails etc AND did an oil change,
but the startup noise is still there (and loud too, this is no little rattle)! The 400 is the 4.2L V8 and the tnsioner does have a pressure check valve (so I'm told), but will drain out after a long sit...

BOBB