Is this the sound of rod knock?

[dkad260]

Can you mount a GoPro in the engine bay or on the frame then drive it? Sounds too high pitched for a rod, are you sure it's not an exhaust leak? Any dark soot near the manifold and head?

 

[dkad260]

Actually sounds a bit rapid for an exhaust leak. Have you pulled the inspection plate from the bell housing and taken a look at the converter bolts?

 

[jeremiahm]

All exhaust bolts are tight and the pipe test shows all are quiet at idle. I don't have a GoPro, I did get a bluetooth lapel mic, but there is too much noise in the engine bay to make out any sound. When I changed the starter 3 weeks ago I got a wrench on each of the converter bolts and all were tight. My normal mechanic can't hear the sound on test drives, even when I am driving and hearing it. I have not had a chance to take it for a second opinion. At idle the only odd\louder sound on a stethoscope is between cylinders 3 and 5 at idle. The easiest way to hear the sound is on the section of road I recorded at night, during the day it is not as distinct due to traffic.

 

[dkad260]

When my rocker was making noise, it would tend to go away with the idle raised. I did replace all of them before the noise got worse. However I did notice sometimes raising the idle did not diminish the noise.

I wonder if you might possibly have 2 worn rocker arms or pushrods, which may give you that rapid rattle sound.

The rocker arm bolts are a 1.25mm pitch, go/no go is about 1/2 turn....basically less than 1mm of preload., so doesn't take much.

Did you watch the video I linked earlier?

 

[dkad260]

I would pull the LH valve cover and check the rocker arms.

 

[mikeyss]

My original L9H dropped a valve seat, and it made a similar noise. With mine, weeks before it happened it made sort of the same sound you're hearing. The valve seat cracked in half, then half fell out of the head and made contact with the piston, while the other half jammed the valve open. Here is the video of mine before it blew up:

 

[jeremiahm]

@dkad260 I just re-watched your video, I don’t get that sound. In fact, it is quiet at idle. I only produce the sound under load.

@mikeyss I don’t hear a sound like that either.

Thank you both for the feedback. I will try and find time to pull the valve cover this weekend and see if anything is wiggly.

 

[jdwood1111]

My original L9H dropped a valve seat, and it made a similar noise. With mine, weeks before it happened it made sort of the same sound you're hearing. The valve seat cracked in half, then half fell out of the head and made contact with the piston, while the other half jammed the valve open. Here is the video of mine before it blew up:

That sounds unfortunately very close to my noise. I have been trying to find other videos that sound similar to mine and this and only one other where the gentlemen replaced a loose lifted and resolved it. I have been meaning to try and remove the valve covers to diagnose but have been way too busy with work and home (5 kids) to do anything about it. This is jump starting me. What did you end up doing, replacing the motor?

 

[jeremiahm]

I pulled the valve covers this morning. All the springs are good. All rockers have a little side to side play at top dead center. No excessive lash. I think I will drop it by the transmission shop this week for a proper torque converter bolt and flex plate inspection. When I changed the starter a few weeks ago, I did put a wrench on the flex plate bolts and they were all tight annd I didn’t see any cracks. Are there other bolts for the TC as well?

 

[jeremiahm]

On a side note, my check tire pressure warning and DIC have been on for a year because my sensor batteries are dead. After putting the truck back together and plugging the battery back in I have no more warnings! The DIC still shows no pressure on any tire. Strange but great