Does anyone get a chattering noise for the first 2/3 seconds on a cold startup? My old 98 Navi did this and now my 07 does as well. It only happens if the truck sits for at least 3-4 hours OR the first startup after an oil change (does it longer the first time) and and goes away after a few seconds.
It seems to be worse in the cold/winter but not sure what it could be.
I had a tapping that just never went away at 10K miles, ended up replacing one of the heads. THen at 50K or so I got a marble sounding rattle on start up. It ended up being the timing chain tensioner gaskets and tensioner arms worn out. After they replaced that its fine.
They need to remove valve rocker arm covers, front timing chain cover and the parts are about $250. Not sure what labor will be as mine was under warranty. I would guess your looking at $500+. Get a price before the work is begun. They know what it will cost.