High pitched squeal/chirp when starting cold - NOT BELT!

[omero]

Hi

I have a 2007 ford explorer XLT 4.0 SOHC. When starting cold, I have that chirp for a couple of seconds then it disappears. When starting a warm engine, no sound unless it's a cold day.

I started with the common sense solution, changing the belt and tensioner and checking all other pulleys with no luck. After that, I removed the belt and started the engine and the sound was still the same.

So, now I know that it's not the belt. What could it be???

Thanks,

 

[Town]

By removing the accessory drive belt and starting the engine, and the chirp was still there, you have eliminated the belt, alternator, coolant pump, idler pulley, coolant fan, power steering pump and A/C compressor as possible sources. That sounds like most everything that could cause a chirp.

The starter motor has a support bushing for the shaft that should be lubricated, could create a noise if dry and cold weather would shrink the tolerance. Are the starter mounting bolts tight?

Have you tried having an observer try to identify the sound location while you start the engine, or vice versa?

If you connect the pos battery terminal to the starter small electrical connection after removing the wire (it comes from the ign starter relay) you can turn the engine over without starting the engine. A momentary switch is often used for this to provide good control over the process. That may give you more time to check for the noise.

Good luck.

 

[omero]

Thanks a lot Town, I'll check the starter and sound location and post back.