Quick background ... I completely rebuilt my 1998 F-250 4.6L after a broken spring dropped a valve and destroyed a cylinder. About 6 months ago, I got to the point where I tried to start it with a 4.6L engine out of a Grand Marquis. It did, but the smoke was rolling. Eventually decided to get the intake manifold planed (it was pitted pretty bad) and spend a bit more on a quality gasket. A compression test with a leak-down tester showed all cylinders to be getting good compression. After slapping all that back in, with a brand new alternator, I tried to turn it over. The starter, however, didn't want to do much of anything. I swapped out the starter for a brand new one, which is always good fun. My hands and forearms look like I was trying to give a feral cat a bath. When I went to turn it over, the starter certainly gave it a good effort, and the lights and all dimmed, but it still didn't seem like there was enough power to properly engage the flywheel and turn the engine over. I've confirmed that the crankshaft pulley turns about as well as can be expected. No unusual resistance. I also tried using the battery out of my 2000 Expedition, which is a fairly new one, and had the same result. I'm now suspecting an electrical issue of some sort.

Any recommendations on where to start looking first?

-Steve
Titusville, FL

 

Cable connections at both ends. Doesn't the starter have to be shimmed properly for the starter gears to be the correct distance from the flex plate gears?

 

I agree about the cables and good clean connections.
The starter draws a lot of current so any resistance in the total circuit will drop voltage across it and lower what it left for the starter motor.
Be sure the cable terminal and posts are clean, the start relay is tight, the start motor terminal is tight and grounds are clean and tight.
If the motor was out for rebuild are you sure the converter did not come forward and then get indexed wrong going back in.
If yes it will destroy the front trans pump and may be hard to turn over.
Good luck.