Extremely strange starter issues on Ford F-150

[Rhys]

Hey everyone, I have a 99′ Ford F-150 with 4.6 V8. Recently the starter failed on me, I noticed I had really bad connections on the solenoid so I cleaned and tightened them all up. I even went as far to clean the ground on the frame up with new washers, install new battery terminals, and install a new positive battery cable(Which were both worn). Still just a loud click when I turned the key to start. So I replaced the firewall starter relay and that was working fine. So finally after all of that I pulled a used starter off a 2000 Ford Expedition, put it in my truck and it started twice just fine. I cleaned up the ground to the bell housing where the starter sits as well. The second time I started the truck after about 5 seconds of running, I revved it a little bit and heard a sharp click noise, the lights in the cab got abnormally bright and then dimmed down, and the battery light came on. So I shut the truck off, went and checked the starter and the solenoid had a small amount of smoke coming off it. So I went to see if the truck would start again but did the same exact click it did with the OEM starter. What is going on here? I know all the wires are in the right place, I checked a diagram, and the original starter died in the same exact way except the solenoid didn’t smoke. Just made a loud click sound and then wouldn’t start again. So weird! Any ideas?

Topic

[Its me]

You may want to visually check your flywheel/flexplate condition… perhaps it may be loose, cracked or something with the teeth…

Karl

[valde]

Another possibility is that you have bad ignition switch, starter relay or solenoid that causes starter to engage by itself. That can cause starters to fail. If exactly same thing happened with old starter relay and old solenoid then only thing left is ignition switch (or unlikely wiring) or flywheel/flexplate if that is possible with that engine.

[Rhys]

I thought of that, but I’m not sure that the flywheel would be the cause of two starters failing electrically. I think it must have something to do with the starting circuit.

[valde]

If something causes starter to engage when engine is running starter will over rew and overload its windings.

And things that can cause starter to engage when engine is running are:
-Starter itself (already replaced)
-Solenoid (already replaced?
-Starter relay(s) (already replaced)
-Ignition switch
-Flywheel/flexplate (depending on how engine is designed)
-Wiring (unlikely since you need two wires to touch)

[Lorrin Barth]

Maybe it is as simple as you buying a defective starter with an internal short. Because I am the curious type, I would pull the starter and take it to a shop that repairs starters and ask them to test it and if it fails then ask them to pull it apart and see what is wrong.

[EricTheCarGuy]

It may very well be that the starter is faulty. It’s worth checking into I think. It think it’s also worth checking into the theory about an ignition switch problem. Just for good measure, you might also want to check system voltage. If you’re having a charging problem, or a problem with the battery, it may also cause an issue like this.

Good luck and keep us posted on what you find.

[Author]

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