I flushed and filled my cooling system a few weeks ago when I did my opti install. I thought I properly bled the system and it was running fine the past couple weeks although the temp gauge would go up to the red mark when sitting in traffic for a few minutes. I thought nothing of it since the fans didnt have to come on and the guage would go back down once I got moving again. NOW, it was fairly hot out today and after I shut the car off from driving coolant started overflowing from the reservoir. I opened the bleed screws w/ engine off and steam hissed out for almost 5 minutes straight. Then I opened the radiator that was now very low so I filled it up let it all cool down. Filled the reservoir to the right amount and bought a new radiator cap for good measure. Opened bleed screws w/ engine running and liquid flows. Drove it around and overflows again once you shut it off. Air will hiss out of the screws if the engine is off, coolant will flow out with engine on. Turn it off again, and theres still more air. So where is all this air coming from? I'm fearing I have a bad head gasket. Another WIERD thing I noticed while under the hood when it happened, just after I shut the engine off, the serpentine belt was moving ever so slowly for about 30 seconds. Like something was forcing the crank ever so slowly causing the belt to turn the accessories.

 

Also, I have NOT noticed any white smoke from the exhaust, or any oil in the coolant or coolant in the oil. So the whole head gasket deal is creeping me out.

 

Are you making sure the block is full of fluid also. You've gotta wait for the thermostat to open and pull coolant into the block before you continue topping it off? Also try putting the car up on ramps and having the radiator cap off and have the car running. When the coolant starts cycling through any air pockets you have will go to the highest point to escape and that should allow the system to be completely air free. I bet that's your problem.

 

thats good because those are some symptoms of a bad head gasket. my guess is the water pump. sounds like its not pumping the coolant through the block to keep it cool. how long does it take for it to over flow or overheat (get up way in the temp guage) when you first start the car when its full cold (sat overnight) if it heats up real quick could be the waterpump. oh just thought of the thermo also. check that. if the thermo is staying closed and not opening coolant wont flow and cause a ton of pressure thus overflowing the radiator. check it out an dlet me know

 

Yeah I forgot about the WP....If it's peeing out of the weep hole that's your problem. Did you swap thermostat's at all? Either yours could be bad or if you swapped you have to make sure you get a reverse cool thermo. A regular V8 one will not work and it will cause you to overheat.

 

My themostat is a new Hypertech LT1 160 degree, its working right. No signs of leakage from the water pump or anywhere else in the cooling system other than the reservoir overflowing. It takes about 10 mins of highway driving at first plus a good 10 mins of stop and go driving for it to overheat. Mainly, I believe its the stop and go thats causing it.

 

did you say that your fans were coming on? are they coming on at all? stock programming is something like high speed at 232 or something and low speed until 220 or something. do u have programming? hpp3? manual fan switch? if ur fans aren't coming on when it gets real hot it could casue this maybe. in stop and go it still shouldnt over flow and come out your raidiator. bleed some more an dmake sure therse no air int he system for sure. try draining all in the radiator and refilling with the bleed screws oopen until the air does come out and just coolant flows. then start and run and do agian as the coolant flows the coolant level will drop so add accordingly. hope u find out wahst wrong.

 

The fans havent come on. I know they work though cuz they come on if I turn the a/c on or if the SES light comes on for whatever reason. No manual fan switch.

 

did they ever ocme on when it got real hot up towards the red mark on teh temp gauge or b4 it overflowed? has to be something in the cooling system. can u drive long distance? like on the interstate what temp will it be? should be around 175 180 or so. dependingo n humidiyt an dheat outside.

 

Sounds like a head gasket. Your weird description of the belt moving after the engine was off, I have never heard before. If the crank was indeed turning, the only explanation in my head would be that steam in some cylinder with the valves closed is causing compression and making it turn.

 

Thats what I was thinking.

 

I used to have an overheating problem because the water:coolant ratio was too high. It was below 25% antifreeze if I recall and at a certain temp not far above 100 it would boilover (wouldnt quite blow the cap right away, actually it went to the overflow tank if i remember) but you knew it would happen because as soon as it reached a certain temp the temp would rise much quicker after that.
This is because the boiling coolant mixture cools even less of the hotspots on the block because of the bubbles...

 

I did a 50/50 mix.

 

ok, i have a few questions. i have 96 ta and i have a fan switch. when i start the car, i turn on the fans right away just cause its like 100 degrees outside...after a while temp gets to 210 and stays there. it might go just barley above/below 210, but for the most part, its right at 210. about a month ago i had a leaky radiator, and i took out the thermo to help with cooling and i just havent put the thermo back in. i just put in a new radiator like 2 weeks ago and my low coolant light is always on. i check coolant level, and its good. im thinking its just a bad sensor, but im not sure. now, when i bleed the system, do i just go outside in the morning when the car is cold and open the screws? or do i drive around and get the car hot, and then open then screws?

 

You want to leave the thermostat in when your running the car. Without it being closed sometimes the radiator never gets a chance to cool down the coolant. I'm sure that's your problem. It kinda works as a cycle. Lets coolant into the radiator, cools it down, lets it back into the engine(and cools the coolant that was once in the engine) ect,ect,ect. If it's constantly flowing it never has a chance to cool down enough, so yeah it probably is hovering around 210. Also if your coolant is full but your sensor keeps coming on yeah it's probably the sensor. It's about halfway down the radiator on the side of it, passenger side. Try taking it out and cleaning it, that might work. If not you'll have to get a new one, beware their kinda pricey(30-50 bucks). Also with your bleeder screws you want to start the car when it's cold, open the screws and let it run till it's up to temp. Once all the air has excaped out of them tighten her up.