I wish this was a joke but I bought a 1999 Navigator with a 5.4 at auction that had a dead battery. Paid $350, When I got it started it knocks LOUD. I cant even tell where the knock is coming from its so loud. When I start it up it runs good, and after 30 seconds to a minute the knock goes away at the same time the oil pressure drops. Could this be a bad timing chain tensioner issue? Under 100,000 miles on it was all the bells and whistles and is in really good shape otherwise.
PS its cold in North Dakota usually till may so I have time to research this till I am going to work on it.
Thanks for any help.https://www.f150online.com/forums/im.../DeadHorse.gif