Ford Fusion 2007 SE I4 - Grunting!

[Wheelman]

HELP! my 07 Fusion SE I4 is making an awful grunting noise on cold start when it's damp/humid out. I figured maybe it was in the ignition so I installed new spark plugs, no luck. The dealership told me it was the belt tensionner so I put in a new one, again, no luck. the noise happens when the engine is cold and it's humid outside and I put it in gear. when I turn the A/C off, the noise is less so I figured it was something belt driven but I can't find it. also, once the engine warms up, there is absolutely no noise, purrs like a kitten regardless of the weather or the belt driver accessories turned ON/OFF. my local mechanic is also out of ideas... the noise is a weird grunt that seems like the valve train is having an awful hard time and it's oftenly complimented with a belt squeaking noise. the serpentine belt and its idler are relatively new (20000km) and the car has 120000km on it. there is no distinctive loss of power when grunting though. I'm running out of options and those trial and error parts are starting to take their toll! Any ideas? Please Help!

[carsandcycles]

It sounds like a chatter in one of the shafts to an accessory, i.e., alternator, water pump, a/c compressor clutch; alternators seem to be more prone to this.

[thcardoc]

The last thing anyone should do is start the guessing game. The best approach would be to first remove the serpentine belt and allow the vehicle to sit so that the conditions that cause the noise can occur, and then start the car to see if the noise is indeed gone. If so slide the belt back on ansd see if you again have your noise, and then remove it again and again see if the sound is gone. We use directional microphones with headphones to help isolate the source of engine noises, as well as the traditional stethoscope.

That being said, the damper pulley is a common failure component as it has a bearing inside it that allows for smoother movement when its in good condition but can be noisey when it fails. Your's may be just starting to fail.

There are also issues with the balance shaft assemblies, however your's may or may not have that as it wasn't used on all of the engines.

Take note! You cannot just pull and replace the damper pulley as the crankshaft timing gear is not keyed. If you remove the damper pulley bolt you will lose your cam timing and then when you try to restart the engine you could do severe damage to the engine if you dont properly time, and lock the cams and the crank in their proper positions prior to any dissassembly.