2006 Ford expedition 5.4l squeal while trying to start

[gutsnthegrass]

As the title states, we have a 2006 expedition that intermittently squeals something fierce while trying to start it up.  It doesn't do it all the time, but when it does, it sometimes takes it up to 15 time to turn over.  I replaced the starter awhile back thinking that would solve the problem, and it did seem to help, but it still does it and it is getting worse.  Any other ideas?  I was thinking maybe the flywheel had a worn spot too, but don't know.

Thanks

[Woodchuck]

Can you record the noise and post it?

[Zardoz]

IMO it does seem like a starter/flywheel problem. I would pull the starter and then have someone wrench the crank bolt while inspecting the flywheel ring gear for problems. It doesn't take much of a wear problem on the ring gear to cause problems starting. You should also be able to scuff marks on the starter gear. If everything "looks good" I would try putting a thin shim between the starter and bellhousing to move the starter out a few thousandths to see if it help.   

[jackelope]

My over the internet unofficial guess would be teeth broken off the flex plate. You'd have to inspect the flex plate to verify.