Failure to start

Sometimes when I try to start my 2005 Ford Taurus, there will be a grinding like sound and it doesn’t start. I keep turning the key off and on and sometimes even take it out of park into neutral before it will finally start. Can take anywhere from two to six or more times of doing this. We have replaced the starter and that didn’t help at all. My husband, who has a mechanical degree and his friend who can usually fix anything, have been unable to determine what this problem is. Any suggestions?

If you hear a grinding sound when trying to start the engine, the ring gear on the flex plate may have missing/gnarled teeth. Remove the starter and inspect the ring gear teeth for damage.

Tester

We will try your suggestion. Thanks.