Honestly, I'm not sure anyone from this thread still exists on here as its 10 years old. The person you quoted hasn't been online here in more than 5 years.

 

Smoke machine for a coolant leak is false. That would not work. Licensed for over 12 years and I can guarantee that wouldn’t be a valid method for coolant leak testing.
Best methods: Pressure test then look for leaks, ultra violet dye, boroscope and mirrors to find hard to find leaks. As for the 3.4 leak problem my guess is the factory block heater assuming the intake was done properly and not leaking again.