07 compass cooling issue. please help!
so i have a friend that has a compass that has started having cooling issues. what happened is that the temp , while driving, go up to about 3/4 of the way up. i would turn the heater on and it would drop to 1/2, no immediate, but i would. i was thinking it had an air bubble in the cooling system because his cap was bad (broken seal, could see residue of old coolant on intake man, and plastic cover). replaced the cap, bled the system as much as i could, and still had the same problem. so i was thinking it could be a bad tstat. took them out and tested them. the 203 degree one would not open. so i replaced it, bled the system as much as i could and it still did the same problem. so i said screw it and put a new 170 degree in as well, now both are new tstats. bled the system and topped off the coolant, same issue still. then i was getting irritated and i took them both out for giggles. bled the system, topped off the coolant and it stayed at 1/4 idling in my driveway. i let it idle for about 15+ min and it creeped up to 1/2, then the fans kicked on. let it idle for another 10 and it went to 3/4. at this point i am dumbfounded, so i took it for a spin around the block to put a lot of air through the rad. the temp dropped to about 1/8th like i thought it would. i let it idle in my driveway for about another 10 and it didnt get above 1/4. im still dumbfounded. i dont want to run the car without any tstats in it, so here are my questions:
why would it act this way with good tstats?
would it be a water pump issue?
am i blind or is there any sort of bleeder valve for the cooling system?
is this a problem with compasses and should my friend just trade it in? (lol)
i didnt see any oil in the coolant or coolant in the water or any other signs of a blown head gasket. there are no leaks in the system and the heater blows warm. i dont believe there to be any air bubbles in the system at this point, but it acts as there is when the tstats are in there. any help would be greatly appreciated as i am just scratching my head to figure this out.