I noticed this sound this morning. It was loud enough for me to hear it in the cab. I checked the valve springs and they are ok. Then I noticed it is louder from below. The sound increases proportionally with engine speed. It seems to be coming from the rear of the engine. I do have oil pressure. Now the truck is parked until I figure out if it's safe to drive.

Does anyone know what it sounds like? I hope it is not something serious

It's a 2003 6.0 with over 100k. The sound just appeared out of nowhere this morning.

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

 

If I am hearing it right, my speakers are the greatest, it sounds like the noise is half the engine RPM so I would be thinking valve train related. What all have you checked? Just springs?

 

check the exhaust manifold gaskets. Sounds consistent to just 1 piston so MAYBE you have a leak. Mine leaked once and it sounded like the rockers were hitting the valve covers.

 

check your torque converter bolts also

 

Yes I only looked at the springs and made sure the rocker arms were not loose. I need to get a length of hose tomorrow to try to pinpoint the location of the sound on the valve covers because I was in a hurry today since it was getting dark.

I did have a header leak against the head on cylinder 1, but it was not the source of the sound.

I will check the torque converter bolts too. I thought about that, but I wasn't sure what a loose one would sound like.

I will also check the flexplate for damage.

 

The noise sounds a little slow to be a flexplate or converter bolt to me, the speed of the sound makes me think valvetrain...

 

Thanks bud. I'll be sure to use a piece of hose or pipe to listen against the valve covers and see where it's coming from.

What parts in the valve train would usually cause this type of sound?

 

Maybe a lifter?

 

Bump for Friday.

 

Id start with checking around the header to see if it's leaking. It's the cheapest fix. are you using stock GM exhaust gaskets?