So after a very long rebuild of my deceased dads truck it is locked up. When I got the engine I could turn it by hand perfectly. Has been in the truck about 6 months without oil or having been turned at all. How do I unsexiest it. Some say diesel fuel some say ATF and acetone. What’s the best way? I have all plugs out separated from tranny etc I’m not a rookie I have traced every other possible problem. It’s a 5.4 engine that has around 92,000 miles on it. Belonged to an elderly woman who just drove to the store and church she was t boned and died on impact so I pulled the engine from her vehicle. Need to get this done fairly quickly

 

take all spark plugs out, and soak the cylinders liberally in a penetrating oil of your choice

 

This

 

I can remember working on an old Cadillac engine (1947) and I thought the engine was seized. As it turns out, the water pump was frozen on it and, in turn, all the belts were locking up. I suggest pulling off the serpentine belt and, if that doesn't work, as someone else said, pull the plugs and dump ATF in each spark plug hole. It might take a few days of back and forth on the crank but you should eventually break it free. Once that's done drain the oil (obviously) and once the engine is reinstalled, fill with something cheap and seafoam it. Another oil change and you should be good to go.

 

Little old lady might have only driven it to church

That dont mean she didnt have manifold or hg leak putting coolant in a cyl

Everything looked good when you installed it?

6 mo isnt long ... Id also start by making sure nothing to do with accessories.......then soak away...

 

If Chandler, TX is located in humid TX you might try pre-lubing the engine a couple of times a day for a couple of days also if it's been without oil for six months. Have you pulled the oil pan plug to see if anything comes out.

 

Seems unlikely to seize up after just six months. Are you still using your hands or the starter? Is it in neutral?