Cranking issues
 

I copped a 3.5 from a junk yard, and dropped it in an 03 that I previously removed a blown motor from. When I hit the ignition I can her the starter engage with a big click. But it didn't turn. So I turned the crank pulley with a ratchet. It turned a few times, then got hard to move. So I went back, and the motor turned a little, when I hit the starter, but stops, and doesn't turn anymore. Anybody ever have this problem? And what was the issue? Thanks in advance.

Sounds like starter motor shot, does the engine still turn by hand?

check all your grounds, mabye you forgot one when you dropped the motor in. i saw a friend do a motor swap on a pacifica and because he forgot to hook up the tiny ground on the passenger mount, the car wouldnt even engage the starter!! i held the ground to the moung and it fired up every time. did you sand down the bellhousing from engine to trans? the surfaces have to be clean for a good ground connection. if you didnt, you can back out the closer of the starter bolts, put a ground through it and comnect the other side to the negative on the battery.
i had a clutch job done and the surfaces were not clean and i was burning out starters because they would either click and not move or crank all day. grounding the starter gave me a perfect start everytime i try now.

I turned it by hand, it turns a couple of times then it stops. I tested the starter before I took the old motor out. After turning it, it's crank a little, then it stops. If I attempt to start it again, it'll just click real loud.

You say turns by hand then stops? Stops against compression stroke or siezes?

It seems to be compression, because I was once able to make it pass where it had previously stopped.

Did you do anything to the engine before you installed it?

I pulled the plugs, cranked it, and oil shot out, of the cylinders. Someone said the motor may have been turned upside down or something at the junkyard. So I'm gonna clean everything up later, put some new plugs and see if it turns over. Thanks guys.

Can you turn it freely by hand without the spark plugs in the cylinders?

If not there might be real issues

It's turns freely now. I put back the plugs, and it's cranking. Didn't start yet, but I'm about to hit it with some spray and see what gives.

Check compression while you at it

I was getting an IMMU code so I got the key guy to do something with the key programming. Anyway, now it's turning over, and catching a little. It's starting but not enough to run on it's own. There's exhaust coming out, so it's burning fuel. I'm wondering if I could be having a throttle body issue.