ONLY when started cold my engine sounds like this

http://www.youtube.com/watch?v=nBKy9nko5nI

This is only when it has sat over night and it isnt at 1st, you give it a little gas it makes the noise after a little bit it quiets down and is barely herd unless flooring it next to a barrier on the hwy.

Oil is fresh and clean and it has maybe 5K miles since I replaced the whole valve train and oil pump/chain/gears.

Is this what I fear and the main bearings starting to go?

Oil PSI cold is at 50, when run HARD itll be at 30 when cruising 15-20 when stopped on a hot day after driving for and hour. The only funny thing I have seen with the gauge is at times when its warmed up itll be at the 30 on the hwy i nail it, it dips down to 20 and slowly climbs, I let off the gas it flies up to 45-50 and then dips back down to 30.

 

or could this just be piston slap?

 

Sounds like piston noise to me.

 

The only funny thing I have seen with the gauge is at times when its warmed up itll be at the 30 on the hwy i nail it, it dips down to 20 and slowly climbs, I let off the gas it flies up to 45-50 and then dips back down to 30.[/QUOTE]

This is weird. I never have had an oil pump go out on me, but I'm wondering if that's what's going on with yours. Not sure man. Hope you get it figured out.

 

A brand new oil pump already failing?