Piston slap or valve noise or something else?

[gtfs]

Hey guys, long time lurker and first time poster here.

My 2003 V6 MT with 131,000 miles has been making a knocking/tapping sound on cold starts. It sounds somewhat regular and gets louder under load. It starts diminishing after about a mile and disappears completely after about 2. It sounds like it's coming from right around cylinder 5.

I first noticed the sound a little bit ago after coming back from a 3 month trip. I asked my roommate to drive the car once a week or so, but I don't think that happened.

I did a valve adjustment last summer, and after hearing the noise took off the covers and checked the clearances again. They seemed to all be in spec. I could have missed something, though.

I haven't taken it in to get looked at yet. I'd like to get your guys' opinions first. Link below is to a video I took. Fast forward to around 30 seconds in. The quality and camera work ****s, but the noise is pretty obvious.

You Tube

You Tube

[Doude]

Have you checked if your spark plugs were while tighten?

[gtfs]

Haven't checked the spark plugs. I switched them out at 105,000 about 2 years ago.

[SatinSilver]

Send a pm to "Fredsvt" with a link to this thread.

[gtfs]

Did so. Thanks.

[GenXer]

It's hard to tell from the video but it DOES seem slightly irregular or noisy, however some noise when cold is normal. You can listen to the engine with a steel rod or big screwdriver held against the engine with the other end next to your ear (I know it looks weird), but if you try it in different places it might help you to pinpoint the noise.