You need to remove the starter and look at the teeth on both parts.
Remove the starter and inspect the ring gear on the flywheel.
if the starter is bad you will hear one single click, if the flywheel is bad it will sound like a heard of daemons are trying to exit from under your vehicle. if its your flywheel you will know what i mean by the comparison
Assumeing it's the same starter, the bendix(the gear on the end of the starter that engages the flywheel)could be bad, and or the starter it self could be bad. sounds like number of teeth on new flywheel does not match number of teeth on starter. find out from mechanic that installed new fly wheel, how many teeth on flywheel if he doesnt know, a ford dealer can tell you from the part number on your receit. then ask how many teeth should be on starter to match fly wheel pull starter and count teeth
is the problem,that the flywheel teeth are being chewed out and same on starter. or is the problem that starter and flywheel do not mesh properly when engaged? if either of thses is the problem,this means that the gear on the starter is not matched to the teeth on the flywheel. other problem that could be causing this is none or incorrect shims used when installing starter motor. to fix this, you need to make a mark on the flywheel(use white out or something like that),and count the number of teeth.then do same on the starter motor.then find out from a drive line specialist,how many teeth shoud be on starter motor to match the flywheel.they can also tell you the shims to be used when installing starter motor to get proper clearance.
Remove the starter and use a pry bar to move the ring gear.
Pull the starter motor so you can see the flywheel. Make a chalk mark on the flywheel. Have someone turn the engine over by hand while you watch the flywheel turn one revolution. Look at the gear teeth and watch up in there for flexing and cracks and see that the bolts are all tight.
Have an experienced mechanic listen to the starter as you engage it and crank the engine over. He can tell if the starter is to tight, to loose or just right. There is a process to measure the correct spacing between the starter drive and the flywheel. Not easily done by a non-mechanic.
While I'm not familiar with this exact model, I can tell you that you should expect to find it mounted to the front of the flywheel, typically on the right side of the car. I may be wrong about it being on the right side in this case, but it'll be attached to the flywheel.
That can depend on a lot of factors. Most intuitively to me is that the gears on either your starter or flywheel have been stripped or worn down. This is probably the case if when you turn the key to start the ignition the starter motor opperates, and accompanied by a metalic rattling, buzzing, and/or grating. It usually isn't too hard to get to your starter. It is located up against the bottom side of the engine block, and up against your transmission bellhousing. I am not sure exactly where on an F-150, but a haines manual can tell you. If you can get to the starter, and pull it out you can check to see if the gear teeth are worn on it, an with a flashlight you can check inside the bellhousing to see if the teeth on the flywheel are worn. you may have to take off your exhaust, or put it up on stand to get it. Good Luck!
I remove the starter and test it, then take a pry bar and try to tun the motor over by inserting it into the teeth of the flywheel.
Either 153 or 168. If it has an automatic transmission, it's 153. If it's a manual transmission, it will have 153 for the 1.5" clutch and 168 for the 11" clutch. An easy way to tell is the starter bolts. If both bolts are the same distance from the starter nose, it's a 153 tooth flywheel. If the starter bolts are staggered diagonally from the starter nose (one is farther from the nose than the other) you have the bigger 168 tooth flywheel.
The starter is just one part of the starting circuit that includes the key switch, battery, solenoid, and wiring. If any one of these parts fails, the starter won't activate. If you hear a click from the engine compartment when you turn the key to 'start' then you have a good circuit to the solenoid. The click you hear is the solenoid pushing the starter gear into the flywheel. Normally the starter motor starts turning at the same time to rotate the flywheel, which is connected to the crankshaft. If this is not happening, make sure the battery is fully charged. Check the engine compartment for burned or missing wires between the battery and the starter, or loose connections. If you hear a whirring sound from the engine compartment when you turn the key, it may be the starter gear is not engaging the flywheel and the starter motor is turning. Most modern cars have the starter and solenoid in one unit. Remove the starter and take it to an auto parts store to have it tested. Also check the gear while you have it out. Broken or worn teeth on the gear or flywheel will prevent it from turning the engine. --mark