Opened up the valve cover to figure out why the number 2 cylinder had 0% compression and discovered one of the rocker arms had come off and was just laying on top of the head. Any ideas to why that might have happened?
I also noticed the valve spring was sitting a little lower than what it should have been. Could this mean that trash has blocked the vave from retracting all the way?

Leading up to this, the engine started losing power and overheating about 2 weeks ago. NOticed a knock in the engine. Dealer thought maybe slightly warped heads, but we could not find any type of coolant/oil mixture on the oilpan dipstick.

 

1st, do a leakdown test. Pump air into the cylinder and listen to where it comes out. If it comes out of that valve then you have a problem. Could be a broken spring. Could be a siezed guide. Without looking at it, you're probably going to have to pull the head.

 

Loosened up the cam a little just to reseat the rocker arm and see if I could recreate the problem. After tightening everything back down, the rocker arm is still WAY loose. Thank you Cobra, I will do the air leak test and see if that helps in any aspect. I was pretty sure I was going to have to pull the heads regardless, so that isn't unexpectd