Thread: Car overheating... fixed everything but...

I have a 97 grand prix gt 3.8 with overheating issues that I have reduced to "running hot" issues. It originally overheated due to a cracked water inlet pipe, which is made of hardened plastic. When it overheated the water pump and thermostat went out. Replaced the water pump and thermostat, replaced the $4 water inlet elbow, which required removing the upper and lower intakes - $140 in gaskets. I got it back on the road, although the temp gauge would show the car would get hot rapidly, it would never overheat. I ran a diagnostic after fixing everything, and it said "misfire in cylinder 3" so I replaced the coil, plugs, and wires. It runs like a new car now, but has a rough idle and still runs hot. Ran the diagnostic again - misfire in cylinder 3. Tomorrow after work I'll run a compression check to see if I have a cracked block, cracked head, or blown head gasket. Is there anything else that it could be? If it passes the compression check, I will be completely dumbfounded...

mine used to run hot and have a rough idle sometimes, always had p0303. one week idle was fine then rough two weeks later and so on. i did a compression check with the engine cold. it turned out fine. dont know if temperature of motor makes a big difference but since compression was fine, i cancelled out head gasket or cracked block or head. couple months later i noticed radiator water would shoot up like a geyser when idle was rough. checked it with the block tester and saw that combustible gases were escaping the bore and into water passages. took engine apart and saw a small crack that went from valve to valve on number 3 cylinder head. not saying that could be your problem but check the coolant with a block tester. good luck

I dont have that same issue but i have a similar one.. one day my 2000 grand prix GT 3800 overheated into the red zone in my driveway. right away i changed the thermostat and did a flush and fill just to be safe. Since then it has always run hot. driving at about 40 mph it stays about 210 -215 but when idling or slow driving it runs anywhere from 210-230. i recently changed the water pump and the coolant temp sensor and same problem occurred.. i thought maybe it had an air pocket in it but ive bled it out several times and tried to burp it but nothing has helped my problem. It is 80-90 degrees outside right now... is this normal or can i do something to bring the temp down below 210? PLEASE LET ME KNOW! thanksss

with my car it was the left head. i had some spare heads from a motor that seized on me. put those on and my car ran 210 all the time which was better than before which was 220-230. I just bypassed the computer by cutting the yellow wire from the coolant temperature sensor. that makes the fans stay on high at all times. that made my car run at a perfect 195 all the time. the cool thing is that it doesnt mess with performance, the gauge still works but the computer doesnt get correct temp. my scanner shows datastream and the fuel trims were also still the same and went into closed loop at the right time. i saw online that they sell a bypass harness for a hundred bucks that will do the same thing, that way you wont have to cut any wires but thats up to you. i would try that if i were yall cuz a motor running hot all the time will eventually eat up your head gaskets.