Sticking vavles?
 

I have a 1998.5 24v bought it not running. Guy said he had it looked at and said the vp44 was bad. Had it tested and was fine. While starting I heard a loud valve knocking. I pulled the valve cover off and while adjusting the the valves I noticed one of the number 3 cylinders exhaust valves would stay stuck open then almost "snap!" and close (turning the engine over by hand)

I'm wondering if that was the piston coming up on the vavle and pushing it past the stuck part on the seat or what? Is there anything I can check without pulling the head. It sat for 3 years and the past owner didnt say anything about this other than a bad vp44. I'm at a lose of what to do next. If I should pull the head, or start looking for a new engine this one has 229000 miles.

When you said "while starting", are you indicating cranking and heard the valve knock, or "started" then heard the valve knock after engine started? Sounds like a sticky valve(s) to me, if it just sat for 3 years. Is it an actual "knock" or a very loud pronounced "tick?"

heres a video of it just watch the last 3/4 of the video and you hear the valve "pop" back up

I heard it while purging the air out the lines after putting a new vp44. Just while turning from the starter motor. Once it started running I never heard it. Had a ton of blue/white smoke. Yesterday I went back to turn it by hand to see if I could get it to replicate the sticking after running it a little and putting some sea-form on them. Couldn't, so that was good but what I did do is re-check valve lash. Horrible job I did the first time, possibly cause I didn't know I adjusted it while it was partially stuck down?? IDK Anyways, I got it properly adjusted now and THE SMOKING IS GONE the engine runs great at idle.

Now the problem I'm getting is a dead pedal until I warm up to 140 degrees then all the sudden boom, full power.

Hopefully not the new (used) vp44 I just put into it! Buyer said it to be a good vp44 off his fathers truck who just did a swap for an upgrade. Hopefully not the case?

Any insight on that is greatly appreciated. I cleaned grounds, and I'm pretty sure I correctly reset my APPS.

I really hope what contact that did occur between the valve and piston did not seriously damage anything. As far as I can tell it's good now. I also learned if you let these engines sit for a decent amount of time you'd better check for them to be sticking first and get them unstuck before you actually get the motor started.

THat makes a lot of sense. Hopefully someone will chime in on this. The dead-pedal issue is beyond my ability........
Any codes?