Pontiac Repair: 96 Pontiac Grand Am, blown head gasket, electric cooling fan

Question
In one of your articles, you mentioned about a product that would tell you if you were getting exhaust gases in the cooling system. Could you possibly give me a name of a product to look for.

Yesterday my car ran fine after we changed the thermostat and bled the cooling system, which i might add is not an easy task or quick task to do. i took it for a test drive and everything ran smoothly. this morning i go to work and next thing i know the temp gauge is running almost to the top. on the way home from work same issue. I almost get home and it crosses the top warning line, so i pull over to let it cool and it does. So i am suspecting i am getting gases from a blow by into the system instead of out the exhaust. No water in oil and no oil in water that i can tell as of yet. Car hasn't gotten super hot yet, i always pull over and let it cool down before it gets out of hand. Which has been less than three times since i have owned this car. I did replace radiator, car ran fine afterward, replaced heater core, car ran fine afterward. Now the issue with the thermostat has me stumped. The only thing i did different was after my trip of a test drive into town yesterday i put the heat shield back on that covers the back of the engine. When the car ran fine the heat shield was off. The temp gauge was half way the entire time i drove it yesterday with the heat shield off.

Answer
Hi John:

I do not have a name for the product but the "good" parts stores like NAPA and Carquest will have it. If the electric cooling fan works and this still is overheating it has to be either a blown head gasket or a crack cylinder head. there reallys in no other reason for these engines to overheat. They are good engines but from time to time this happens to them.. What heat shiled are you refering to??