Hey Dan,
I was just browsing through helminc.com (per another one of your posts) and came across this TSB:
"Tick Noise From Engine Bulletin-Cobra Vehicles Built Before 11/1/2002 Only"
Do you have it / know what it says? I have the "tick", but only when the engine's cold. I bought my baby before that date.
If you don't have this TSB then I'm going to buy it, and I'll post its contents when I get it.
Bob '03 Cobra coupe
I just found this on Stangnet. It's probably the TSB in question:
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03-11-4 ENGINE - MUSTANG COBRA - TICK NOISE FROM ENGINE - COBRA VEHICLES EQUIPPED WITH ENGINES BUILT BEFORE 11/1/2002 ONLYPublication Date: May 23, 2003
FORD: 2003 MUSTANG
ISSUE: Some 2003 Mustang Cobra vehicles with engines built before 11/1/2002 may exhibit an unusual engine tick noise that is present at all temperatures during idle. This noise may be due to valve guide wear in the left bank cylinder head. Guide wear manifests itself as a tick noise which can be heard at the rear of LH head, through LH catalyst, at the LH front wheel well and may not be heard with the hood open.
ACTION: Use the diagnostic procedures listed in this article to evaluate the vehicle condition and replace the cylinder head if applicable. Refer to the following Service Procedure for details.
SERVICE PROCEDURE NOTE: THIS REPLACEMENT CYLINDER HEAD WILL NOT IMPROVE OR REDUCE PERFORMANCE.
In order to diagnose noise, the following items must be checked.
Verify noise by placing a stethoscope on the back of the left head near the exhaust ports. Verify that the noise is heard in the left side exhaust system (left side wheel well or catalytic converter, from underneath the vehicle). Try to isolate the noise by canceling the cylinders, by unplugging the injectors one at a time (start with #8 cylinder). Verify that there are no exhaust manifold leaks. Check to make sure that the camshaft spacers are in place. If not, install cam spacers (per Workshop Manual Section 303-01C) and retest vehicle. Check for proper cam sprocket bolt torque, retorque to spec listed in the Workshop Manual Section 303-01C. Check for spongy lash adjusters (refer to Section 303-00 in the corresponding Workshop Manual). Verify that the timing chain tensioner pin has been removed. If the above diagnostics does not eliminate the noise while the cylinders are cancelled, and the engine was built prior to 11/1/2002, replace the left side cylinder head and cam assembly with Part Number 3R2Z-6049-GA. Refer to Workshop Manual Section 303-01C for cylinder head replacement procedures.
PART NUMBER PART NAME
3R2Z-6049-GA Cylinder Head And Cam Assembly - Left - Cobra Only---------------------------------------
That's the one... you can also download the TSB from
PERFORMANCE.
That's the current TSB. There's actually an older TSB that didn't involve a head swap. I had the earlier TSB applied successfully. The main thrust of the procedure was to ensure that the cam towers and spacers were all in place and torqued correctly.
The ticks in this category are heard in a fully warmed up motor. In other words, the sound does not go away by the time the egine reaches full operating temperature. They are usually pretty loud too. You could hear mine from a few feet away.
There is also a cold engine tick like you descibed. I have this sound also. This is most likely piston slap. The forged pistons have a greater coefficient of expansion than hypereutectic pistons so they are allowed a higher tolerance between the cylinder wall and the piston skirt. When the motor is cold the space between the cylinder wall and piston is greatest and the piston "rocks" on the ring and generates this tap. As the motor heats up and the piston expands the space gets less and the sound goes away.
Ford does nothing about piston slap right now and the if you did get the dealer to do the hot tick TSB, including the head swap, the cold tick would remain since it's not in the head.
Some will disagree, but piston slap isn't too worrisome as far as I'm concerned. Lots of motors from low to high output exhibit it, especially when using forged internals. It is possible that it would eventually cause some blow-by, but I think other parts of the motor will fail first in terms of longevity.
Folks who build professional high output motors get rid of the slap by closely managing the tolerances between the pistons and the cylinder walls. But that's expensive on a mass produced motor so most manufacturers just accept it's existence. Interestingly enough, the LS1 motor, even using hypereutectic alloy pistons, had this as a common issue that was, I believe, never resolved by Chevy.
The sound could also be a valve/valve seat issue. But again, as long as it's gone when the motor reaches operating temperature there's shouldn't be an issue.
Unfortunately only time will really tell :).
One last note. If it is piston slap, and I think it is, this is a good reason to stay out of boost when the motor is cold. Putting pressure on a ring when the piston isn't yet completely supporting it may cause problems.
Dan
2003 Cobra Convertible Some stuff and things
PERFORMANCE.
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