Can't help but think you have some other problem, like debris between the head and block.
What sealant did you use? Were the stud theads and block holes DRY when you installed the studs, with the sealant on them?
I don't think missing the torque on a single stud would allow an unpressurized leak. I don't think leaving the sealant off the studs would allow an unpressurized leak.
For a leak like this you almost have to have an OPEN hole.
Your heads don't "warp" that easily, it normally take extreme temperatures. Removing one bolt/stud at a time is not going to hurt anything.

 

I'll take a peak when I get home tonight after work. I did try to run a "pick" with an angle (like a dental tool) to see if I can feel any gaps. But it was on the blind side (rear) so I couldn't see the depth of protrusion.

 

Z28SORR - I did a check but it is possible a hair or something fell onto the surface. I wiped the deck with a cloth and then the cylinder bores to make sure there isn't any dust. But I suppose anything is possible.

Sealant was Permatex High Temperature Thread Sealant.

Most of the holes were dry except the bottom hole in the rear. I looked and there was a little coolant but not a lot. That may be a cause. Will thread sealant work on a damp hole?

You mentioned that even a dry stud without sealant shouldn't cause a non-pressurized leak.

It is a drip and will stream when pressurized to 5 psi.

 

Update - The leak was small and before I rip apart the heads, exhaust, etc to find out what was the root cause, I wanted to run a final test. So, I hooked up a leak-down gauge. The primary concern was to see if there was any air escaping into the coolant or oil which would indicate that the gasket isn't seating.... well, it gave a great reading.

This told me that the leak was only coolant related at the rear of the head gasket. I popped off the thermostat and poured in some Allumaseal directly into the block. Ran the car for 1 minute and it stopped the leak.

I went to top off the fluid in the radiator and bring it up to full temp about 190F. It held on a 10 minute warm-up and no fluid loss.

I'm letting the car cool down, drain the radiator of straight water and top off with coolant. The leak was small and the Allumaseal seems to hold. I'll be watching the gauge carefully for the next few weeks.

Maybe a bit was seeping past a stud. Not sure, but it stopped now.

 

Block dowel pins may be too long? Were the heads milled? Did you set the heads on with no gasket to see if they would sit all the way down? All it takes is one little bur on the pin or hole.

Gm recommends those sealing tabs in out engines.

David

 

Are you talking about the locator pins?

The allumaseal did work but I'm not comfortable with it. I'm tempted to pull the head on the driver's side off this weekend.

I suppose I'll need a new head gasket since this one has been seated (crushed). Or can I reuse it if it hasn't been run.

Also, it is possible to remove the head without popping off the intake? I know I'll have to drop the exhaust on the driver's side.

 

I had to remove a head after final torque as well. I called one of my friends that has been a GM wrench for 30 years. He told me as long as I had not run the engine I could get away with pulling the head and reusing the gasket, but he said if it delaminates or pulls any material that I would need to get a replacement.
So... That is his story. I went with his advice because I didn't want to spend another $60 on gaskets.

 

And the head gasket didn't leak afterwards? Thanks. I guess I'll be tearing into it this weekend.