Looking at buying a 2005 Navigator. Seems pretty nice, especially for the condition and price being asked. EXCEPT...owner/seller says that it needs an exhaust manifold, AND more concerning to me is noisy valvetrain. I have had to replace the studs on my 1998 Expedition due to them failing and suspected the same when hearing the seller mention that his Navigator was diagnosed as needing a manifold. I had expected to find broken studs, but when meeting to inspect the truck I could not hear any leak over the clatter of valvetrain. My Expedition also makes slight noise when motor is cold, but the Navigator was just drove 50+miles and should have been warmed and then some. I realize that this is a different 5.4 and believe a 3 valve dual cam set up. Are these all noisey? Any worries related to this? Any fixes/remedies? Experiences; good or bad? This truck has 114,000 miles on it. My 1998 Expedition has 124,000 and makes me concerned about the additional clatter. Owner/seller says he always ran 5w-20 Castrol Syntex oil. Thicker oil recommended or should it be avoided? Would conventional oil help quiet or worsen the tap tap tapping? Appreciate any help/info (as always) THANKS!!!!!

 

Since I am here....
What is the deal with newer Expedition and Navigator tailgates and their paint. I have looked at 2008s that are like new all over except bubling paint on the lift gates...?Looks just like rust. Are the gates even steel anymore? Galvanized with poor primer adhesion? Thats what it looks like. Plastic or fiberglass maybe?
Thanks in advance again!!!!!

 

They are aluminum with poor prep.

 

Thought it would be something like that. Some really nice trucks I have seen with blemishes there.