So i got a 1996 Pontiac Grand Prix SE 3.1 V6 on 9/23/11 i drove it the next day 9/24/11 and it didnt have enough coolant so the temp creeped until it reached 245 stopped turned it off. Let it sit for 30 minutes then my dad looked at it put water(plain water) in the radiator. and i set off to my house house which was like 3 miles away.i got there everything was fine. Then a week later the car overheated on me and left me at the side on the highway i waited for it to cool down. The next day my dad and I replaced the thermostat and water pump and flushed the radiator. it did the same thing a week later where it over heated almost instantly. Then i explained the problem to my auto teacher he said get a lower temp. stat and let me drill a hole in it so you wont have to bleed it. So i had the thermostat replaced with an 185 degree tstat with a hole in it. now the car runs at 145 degrees because of the hole and gets the ****tiest gas mileage about 16-17 mpg and the coolant gets low about every 3 weeks. The coolant temp stays at 145-155 when on the highway but when i stop it starts to go up slowly until i start moving again. sometimes i turn on the heater on full blast to keep the temp low so it doesnt over heat. Can anyone Help me? i think its the intake manifold that's leaking coolant. Any ideas the car runs fine and there's no white smoke or oil in the coolant or vice versa.
any suggestions?
