4.7L tapping @ start up

From: Al Figols (albatross32672@yahoo.com)
Date: Mon Jun 28 2004 - 11:15:35 EDT


I have a '00 QC 4.7L automatic which now has 70K
highway miles on it. I'm used to the various knocking
and tapping noises that have been part of life with
this truck since it was new, BUT I now have a new
noise to question! Everytime I start it up cold(first
time of the day or after it's been sitting for a few
hours)it taps for a solid minute or so. It sounds
exactly like a hydraulic lifter on a push rod engine
that has bled down. Like a push rod engine hydraulic
lifter, the tapping goes away after a
minute or so(after oil pressure builds?). Is this a
common problem? Could it be that one of the tappets is
bleeding down? Does the 4.7L engine even have tappets
that can bleed down? I do have a background in
mechanics, but I don't have much knowledge of the
4.7L. Mainly because I haven't needed to learn about
it. Any ideas? I hear a lot of horror stories about
these engines. Thanks in advance!
Al

        
                
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