I can only find this TSB regarding a "tick" noise. Hope this helps?
NOTE:This article supersedes TSB 03-16-4 to update the engine, engine build date and part numbers.
ENGINE - ROMEO BUILT 4.6L 2V - TICK NOISE FROM ENGINE - ENGINES BUILT BEFORE 9/17/2003
Some vehicles, equipped with the Romeo built 4.6L 2V engine, with an "ENGINE BUILD DATE" prior to 9/17/2003 may exhibit an engine tick noise that is present at all temperatures during idle. The noise may be emanating from the valve guide area in the cylinder head. The noise may be more prevalent in the front wheel well area and may not be heard with the hood open.
Follow the Service Procedure listed in this article to properly evaluate/diagnose the vehicle condition.
NOTE:THIS ARTICLE APPLIES ONLY TO VEHICLES WITH A "ROMEO ENGINE" BUILT BEFORE 9/17/2003 (ENGINE BUILD DATE NOT VEHICLE BUILD DATE). THE ENGINE BUILD DATE IS TYPICALLY FOUND ON THE ENGINE LABEL LOCATED ON THE VALVE COVER.
Verify the source of the noise by placing a stethoscope on the back of the cylinder head near the exhaust ports.
Verify that the noise is heard in the exhaust system (in the wheel well or catalytic converter area, from underneath the vehicle).
Verify that there are no exhaust manifold leaks.
Verify that the tick noise is still present when canceling each cylinder, by unplugging the injectors one at a time.
Check to make sure that the camshaft spacers are in place. If not, install cam spacers (per Workshop Manual Section 303-01) and retest vehicle.
Check for proper cam sprocket bolt torque, re-torque to specification (per Workshop Manual Section 303-01).
Check hydraulic lash adjusters for a possible "spongy" condition (refer to Workshop Manual Section 303-00).
Verify that the timing chain tensioner pin has been removed.
If the above diagnostics do not eliminate the noise while the cylinders are cancelled, replace the cylinder head and cam assembly with Part Number 4L3Z-6049-AA (RH) or 4L3Z-6049-BA (LH). Refer to Workshop Manual Section 303- 01 for cylinder head replacement procedures.
Wednesday, December 10th, 2008 AT 9:27 PM