1989 Chevy C1500 Engine Problem???

[Blockmason]

Hey there, I'm new to these forums, so please excuse me for any mistakes or if I am posting this on the wrong subforum. Excuse my ignorance. Anyhow, last year I overheated my truck and well hasn't been drivable since. it turns on and all but it makes this noise, I'm no diagnostician nor am I a master mechanic, I can only do the basics.

I uploaded a short video to youtube with the engine running. I'm hoping someone can pinpoint the problem. All opinions welcome. Thank you.

Engine Making Noise

 

[Russ B]

Disconnect serpentine belt and see if still makes the noise. If it still does pull one plug cable at a time to see if problem is in just one cylinder. Do compression test of all cylinders. Good investment is a leak down kit that helps isolate where it is leaking.

Any smoke coming out of tailpipe?