Rapping Sound From Passenger Valve Cover - 4.6

[BarryCarey]

Hey All,

I have a bit of an urgent issue.

For the last month I've had a pretty weird sound from the front of the passenger valve cover under acceleration. Video below

Today it's turned into a rapping. It was bad enough that I stopped driving it and pulled the valve cover to inspect.

As far as I can tell everything looks good. The chain guides seem intact. However, there's a bit of slack on the top of the chain. I'm not sure if this is normal.

I also thought it could be a lifter but they all seem tight.

Cam surfaces seem to look good.

Can anyone give some ideas on what to look for? I'm in a tight spot with no vehicle to commute to work with.


Sound about a month ago:

https://goo.gl/photos/UG6faVRB8RjkVnUz6

Sound as of today:

https://goo.gl/photos/2amTFqY25PAuME5W6

Chain slack:

https://goo.gl/photos/4WpkjKsRsS4BnS2T8

It sounded very similar to this but would get way louder with RPM. (Jump to 1:52)

 

[boominXplorer]

Sure it isn't a loose spark plug or pcv valve? Its hard to tell audible noises on video. Check the followers under the cam for "looseness". They should wiggle side to side when the cam isnt pushing on them but not up and down unless you turned the motor over a bunch by hand (oil would push out the lash adjusters after a few turns of the motor)

Also if your timing guide has worn through into the tensioner plunger you will lose a majority of oil pressure to that head. That will cause a few different valve train noises, not just one cylinder tapping.

 

[BarryCarey]

Sure it isn't a loose spark plug or pcv valve? Its hard to tell audible noises on video. Check the followers under the cam for "looseness". They should wiggle side to side when the cam isnt pushing on them but not up and down unless you turned the motor over a bunch by hand (oil would push out the lash adjusters after a few turns of the motor)

Also if your timing guide has worn through into the tensioner plunger you will lose a majority of oil pressure to that head. That will cause a few different valve train noises, not just one cylinder tapping.

Any idea if that much slack in the chain is normal? From what I can see of the guides they still have meat on them.

Also, here's another video. Still noisy but you can hear it a bit better. https://goo.gl/photos/2amTFqY25PAuME5W6

 

[boominXplorer]

Ok I'm thinking top timing chain guide is broke on that passenger side. Do you have a mechanics stethoscope or a long screwdriver you can put your ear on while it's running? Put it right on the top of the timing cover under the pass side of the alt. The timing guide goes and the chain will hit the top of the cover and will bust through if left alone.

 

[Hugh Janus]

Time for chains, guides and tensioners.