2007 Silverado Knocking noise

[Cocodrie1]

I have searched but found nothing similar to my situation. I apologize if I ovelrokked this topic I have a 2007 Silverado classic 5.3L V8 Flex Fuel 130K Miles. When I start my truck in the mornings or after sitting for a while it cranks and sounds fine. After a few minutes it develops a knocking sound (Very noticeable sound) that last for about 5 minutes. After 5 minutes it goes away and sounds fine.

 

Its just odd that it takes 5 minutes or so for the knocking to start and after 5 or so more minutes to go away after that it sounds fine.

 

Anybody got any ideas or suggestions where to start looking?

 

 

[shotmark]

Read this maybe ??

[mike94silverado]

Knocking is usually an indication of low octane fuel maybe try some premium I had a Dodge ram I just couldn't run regular in because of it

[mattymax]

Top end of the engine ? Bottom end of the engine ?

 

Matt

[Cocodrie1]

Sounds like the top..

 

Like I said its weird that it takes 5 minutes before the noise starts and another 5 minutes and the noise is gone..

[oldmann]

Do these truck idle in 4 cylinder mode? That would sound weird for sure.

[Bad Bowtie2]

Do these truck idle in 4 cylinder mode? That would sound weird for sure.

 

No they do not....

[MaverickZ71]

My '09 made a similar noise when it was 7 months old, during its first summer, after I did the first oil change to a 'better' oil filter (filters more particles out but more restrictive). Took it to the dealer and was told part of it was AFM lifter leakdown after being hot and cooling off (the dreaded "yeah, they all do that" diagnosis), it would tick and knock after startup and clear up after a few minutes of warming up again. The next oil change I switched to Pennzoil Platinum synthetic and back to AC Delco PF48 oil filter (may not filter as good but flows easier), and have not heard the same knocking noise since.