40 psi cranking compression

[vikingpower]

Need some help figuring this one out! Here's the short of it: I recently changed the water pump gasket, then proceeded to be a dumbass and not verify that I had completely filled the engine with coolant. I went driving around and soon enough the engine was pinging a little bit... then all of a sudden felt and ran like I had disconnected a couple plug wires. I limped it back home, about 5 miles or so and put it back in the garage. I checked the oil, still black since I really need to change it. Coolant is still transparent green. So I went and bought a compression checker at Shucks and the 5-8 cylinders (drivers side) are all 150psi. But when I tested the other side #2 was at 40psi. Thus, my question is: did I pop a hole in the piston or break the head gasket?
Yes, I am a dumbass.

 

[rockytoohot]

You definitly have a problem. The only way to find out for sure what happened is to pull the head. Since you still have 40 lbs of compression, it could be a bad head gasket, a burnt valve, or possibly a broken ring land on the piston. If you hasd a hole in the piston the compression would be much less. I suggest pulling the head to see what happened, and if it got that hot I would pull both heads. Good luck.

 

[superhuaman]

Yes you overheated it, it sounds like. Possibly rings or cracked head or gasket.