I35 - Engine Knock - Sounds Like Loose Rocker

[cmorris638]

Need some help here.... a buddy of mine has a 2003 I35 and there is a constant knock under the valve cover that sounds like a loose rocker. I was looking online thinking it was time to replace the rocker arms, but can't find rocker arms for this engine. I realize it is a DOHC and without looking under the valve cover, I assume it has rocker arms or some other type of rocker.

Is there a different name for this type of part? Could the knock be from something else?

Just to clarify, it is not a "tick" like you get from bad or lower octane gas.

Any other thoughts are appreciated? Thanks.....

[the converted]

No rockers, just a cam directly onto a valve shim, then the valve. I know mine makes a bit of a racket, and I've gone as far as measuring the lash and it's within spec. Anyone else have a noisy valve train?

[cmorris638]

Thank you....it really sounds like he's going to blow a rod at any moment. But, there are no rods in this engine. But that's what it sounds like.

Could the "Knock Sensor" cause it to be this loud? Can the Knock Sensor go bad without triggering the Engine light??

[datsunzcar84]

I know in the morning my Max rattles on start up?.?.?

[loystock]

Thank you....it really sounds like he's going to blow a rod at any moment. But, there are no rods in this engine. But that's what it sounds like.

Could the "Knock Sensor" cause it to be this loud? Can the Knock Sensor go bad without triggering the Engine light??

Knock Sensor problem will trigger a fault code (P0325) but will not turn on the CEL. However, a defective KS is not responsible for such knocking sound. The ECU retards ignition timing during acceleration/high RPM to avoid knocking.

[Markc]

If your sure the noise is coming from the cam/valve, then you're going to have to pull the cover and see what's going on. Use a stethescope, (screwdriver to ear), to find out which cylinder is the culprit b4 you pull the cover.