I've posted on this sound I hear before, but have not really come up with anything yet. I went ahead and recorded a video of it from within the engine compartment to help truly display the sound I hear. The scenario that it sounds like this is up a slight hill, accelerating through about 40pmh, the transmission downshifts when it doesn't really seem like it should. The RPMS drop to about 1200 when its making this sound. If I turn off over drive before I go up the hill, it doesn't make the sound.

So far, throwing parts at it, I've replaced the MAF, the plugs and COPS with no change. It does seem like it gets better if I use a couple tanks of Chevron vs the Costco gas I typically use, but that may just be a placebo effect on my part. Any ideas would help.


The video link starts right before the sound, but you can start from the beginning if it helps diagnose hearing normal operation.

Thanks!

 

sounds like the phasers are about to let go

 

Yeah....sounds like a phaser failure about to happen

 

I guess I didn't do a good job describing this issue. I went ahead and had my mechanic take a listen and test drive and he quickly diagnosed a passenger side exhaust manifold leak. As soon as I searched that, I found the many threads the better described my issue. Now I just have to decide if its worth the money to fix it. On the bonus side, he does not feel like he's hearing any chain slap and doesn't see a timing job for this truck anytime soon.

 

If might want to check out my engine noise. Sounds very similar to your truck. I've been told it's the phasers. My truck has 90k.

 

I must say, that does not sound like exhaust manifold leak to me.

How did your mechanic verify this?

 

I don't think my engine compartment recording does it justice. You can really tell that its coming from the passenger side when you are passing a wall. You can see the vapor staining from the cylinder wear the leak is. Plus combined with the symptoms- mainly noticed when under load, not at idle, etc, it matches the symptoms. I've also heard a truck with obvious chains slapping noise, and its different from mine. Mechanic has worked both issues, so he knows the difference.

 

Might have a exhaust leak along with phaser noise

 

The phaser/ timing noise isn't just chain slap. Mine has the typical "phaser noise" and it knocks. It sounds like yours but not as loud. I have no chain slap though (that I can hear) But I won't be tearing into the engine as I don't plan to have the truck much longer. Up against a wall or drive-thru mine is much more pronounced as well.

Best case would be exhaust manifold leak. I replaced mine about a month ago. Much easer than I though it would be after reading lots of posts on it.

Good luck.

 

Thanks, glad you were able to get yours replaced. Reading comments and videos now. I'm hopeful this might be one I can pull off myself. My bolts looks to be in good shape.