Cadillac Repair: overheating, head gasket leak, liquid gasket

Question
had thermostat replaced.checked for leaks,
fans,what is the true test to see if motor gaskets are leaking?
there is not any white smoke comming out of exhaust pipe.cannot find reason for overheating.mechanic installed liquid gasket repair it did not work.what
do you suggest?

thank you


Answer
You can remove the thermostat and make sure that the hole is full up to the top with anti-freeze from where you removed the thermostat. Then remove the radiator cap and using a radiator pressure tester pump up the pressure in the radiator to about 14 lbs and watch the thermostat hole for bubbles. If you see bubbles you have a head gasket leak .

OR you can remove all the spark plugs, Remove the radiator cap and fill it up to the top with anti-freeze and put about 60 lbs of compressed air into each cylinder one at a time and see if bubbles appear at the radiator cap opening.