I have a 2003 Monte Carlo 3.8 V6. Do I need to replace the engine if the head gasket is blown and it has overheated?

If the vehicle only overheated for "like 1 min" like you said then the replacement of the head gasket should fix the problem and a replacement engine should not be necessary. If the motor has been overheated numerous times then there could be internal damage. It sounds like you don't feel comfortable with this mechanic so I suggest you find a mechanic that you can feel comfortable with.

The car runs fine, no coughing or sputtering, just that it overheated and its apparent the I have a coolant leak somewhere, but we are having a very hard time determining where it is leaking because it is not coming out of the exhaust or under the car. Other than the coolant level being low, there is no evidence of a leak. I have stopped driving the car until the problem is found. Any suggestions?

There s a u/v dye that you can put into the coolant to check for leaks. Most mechanics should have some. This might help you locate a leak.

for the car running hot its the o2 heat sensor $18. and for the cutting off it the fuel sensor. hope this helps and saves yiou bundles...thats what was wrong with my 2004 monte carlo ss

I had all these problems.on my 2005 Monte Carlo 3.4 Lt and had gasket and all the other problems.i finally changed the radiator cap and bam no more over heating of course the thermostat was.also.cjanges and it still over heated till I changed the cap