Hi Folks! I have a Fx4 2010 5.4 3V. with 27,000 miles. It runs great, lattely some mornings at start up, I can hear the knok for 1 second. In the last 3 weeks I heard the knok noise 3 times. 1 before the oil change and twice after oil change.

The dealer always change the OIL MC 5W20 and MC 820 Filter every 6200 miles.

Any Ideas? Is that a warranty isue?

 

Hopefully you're using a motorcraft oil filter along with 5w-20 oil.....

 

Yes as posted: "...The dealer always change the OIL MC 5W20 and MC 820 Filter every 6200 miles"

 

How long does it sit before a cold start? Overnight, 2 days, 3 days, or more than 3 days?

 

First off, this is simply a guess. 88 should know better than I......... any chance you are feeding it a super crappy gas? I read that low octane fuel can cause some knocking....

 

Sounds more like your timing chain tensioner loosing pressure overnight they have a rubber seal that tends to blow out