Engine knock at start up

[Hotrod]

I have a 2005 Expedition with 64,000 miles, I am experiencing an intermitent knock on cold starts, after searching online I believe it's the cam phaser as the sound comes frome the front left by the valve cover, the knock is about once every 10 cold starts and lasts about a second. I have always used the 5-20 Motorcraft oil and filter. I took it to the dealer and of course they can't duplicate the noise after several days of cold starts, my issue is the extended warranty expires in a week (just my luck).

Anyway is there any suggestions on what I can do? The dealer charged me to test the oil pressure and crank end-play both came back normal which is what I expected. The theory was that low oil pressure could be making the knock. Is this something I should be concerned with or do these phasers tend to make noise like this?

Thanks!

 

[Hotrod]

Well I can see this topic generated a lot of response.

I will provide and update anyway today the extended warranty company ended up paying for the replacement of the left bank cam phaser, no more rattle! I hope the right side lasts a while since it was not making noise they did not replace that side.