alright, im going to try and include as many details as i can. now i know the camaro heating and cooling system pretty well. ive literally replaced the whole entire system before with the exception of the block. now first for what ive done so far.

new upper radiator hose
new 180 thermostat and gasket and housing
new radiator cap
new coolant reservoir
flushed radiator and system
cooling fan is on a switch and is on from the start just to rule out it not kicking on and the fan does work
found no leaks or vacuum problems after all new parts were in

now the same problem has occurred before and after all that work. Ill start the car and take it for a run when its completely cold. warms up and gets up to normal temp while driving around for a little. i get to city driving or sitting in a parking lot and the temp gauge sky rockets. the heat goes cold. now ill hit the gas and the temp gauge comes back down a little. ill still be on the gas and it goes back up. ill stay off the gas, it will stay right by overheating but not all the way. it will go back up and down randomly by itself as well. coolant is at a proper level when hot. the cars coolant isnt boiling, the block isnt even hot to the touch. the radiator hoses are slightly warm but thats about it. also they are all hard, not spongy, so fluid is going through it all. the car runs fine, doesnt sound or perform differently.

now ive ruled out a lot already. and considering i get heat in the beginning, that should rule out the heater core and hoses. i dont want to run the car because i dont know if it will keep itself in check and the gauge will just be up, or if the gauge will effect the car as well. the only thing i can think of is the coolant temp sensor.
but wouldnt it just be all the way up or all the way down if it was bad? what are your ideas on what the problem can be?
do you think i can drive my girlfriend back to college tomorrow morning without problems or better not move it until something is fixed?

this has really thrown me for a loop. any asap help is much appreciated since i only have a few hours to work with. im trying to research this problem as well but i cant find anything quite like this.

 

basically the gauges say it is about to overheat but i never let it get all the way to the red to find out if it will actually overheat and shut off or not. i dont think its the water pump either, because it does actually work for a little and doesnt go straight to overheating. it just bounces between 3/4 and overheating. i filled the coolant reservoir perfectly, and filled the radiator before turning the car on. then i turned the car on with the radiator cap still off. filled the radiator as it sucked the fluid through. pumped the upper hose while filling. finally got it topped off and put the cap back on. pumped it a few more times to make sure there was suction between the reservoir and radiator.

sorry, im not able to think of all the details at once for some reason. haha

 

still forgetting things. i checked the exhaust, and it has no difference in smell or color. i think thats all the details i have now.

 

either a blockage or air in system. how did coolant look when you flushed it.

 

coolant was muddy. but i literally pulled all the hoses and flushed them out in the tub, poured water through the remaining parts i couldnt take out, made sure water was fully drained out as well. put it back together. and i remember from doing this with my old 94 3.4, that there are not bleeder valves on her. so i had to keep adding coolant while it was running and pump the upper hose. so unless its blocked up in the block, i cant see any blockage in the system. i do know that stop leak fixes stop everything, hence why i dont use them. maybe the previous owner had used a stop leak though and messed something up? i heard about some stop leak removal flush but i dont know if thats real or not since i never went looking for that. i also checked the water pump jacket and that appears to be fine.

..yea.. im beyond confused.

 

i havent seen a air lock in a long time but could be what it is. try parking on as steep a hill as you can find and park with front of car on the up side. let her cool off and open the radiator cap. see if its low, start er up and see if any air comes lose. there is a flow restrictor in the heater hose, it may be plugged but that should do it all the time so heater wouldnt work. only time ive ever had the heat go from warm to cold is when coolant level is low or air is in the system, well unless its turned to cool at the controls.

 

alright, ill give it a try. that seems to be a rather stretch of an idea, but as sherlock homes once said, when you have eliminated the possible, all thats left is the impossible. if this works, you are the camaro god. haha

 

Almost sounds like the gauge itself is acting up, No leaks any where? Check around the heads and behind the block if you haven't done so already. How do the oil and spark plugs look? I'm assuming you flushed the block as well?

 

i did check for leaks everywhere including all around the block. i did flush the block as well. oil is good. no leaks. dirty but clean, level. spark is good. could use new spark plugs but still good. im about to see if the car is cool enough to pull the radiator cap and try it on the hill.

 

i also feel like its just the gauge itself acting up, but when the gauge is going haywire, it makes you uncomfortable and unsure. and if you really care about your car, you dont like to run it if you are unsure. which is me, i love my car too much. haha