Weird coolant system problem

[lokizan2]

2002 impala ls 3.8. This morning i started driving my car and i noticed it was taking a long time to warm up(temp gauge), the gauge stayed all the way at the bottom for about 15 min, then slowly started to warm up, then it just shot all the way up too a notch before red! All this time there is no heat...Then it went down a little below half way mark on the gauge and shot back up to a notch before red. Then the low coolant light comes on, looked under the hood, couldnt spot any obvious signs of leakage, opened the overflow tank and the tank is almost completely full! I replaced the thermostat last year. So through the course of the day i would open the radiator and top it off with fluid to try and get the bubbles out. I drove it and it had pretty much the same symptoms, except this time the heat miraculously came back on, then it would go out again and the low coolant light would come back on, the temp gauge would be steady about halfway up the gauge, then the low coolant light would just go off and i would get heat but just not vary warm. Im wondering if its the pressure cap, thermostat, or head gasket. i cant find signs of external leak anywhere, not even on the ground and there is no smell of coolant in the car or wet carpet on the passenger side floor. The oil looks black and no white smoke from tailpipe, however i did run the car with the rad cap off and fluid started gushing out of it! Im at a loss here, any help is much appreciated.

[maxwedge]

I would replace the t' stat and bleed the system. The bleeder port is on the t'stat housing.

[lokizan2]

OK thanks i will replace the thermostat tommorrow, and could you tell me how exactly to bleed the system. i know where the bleeder screw is but am i suppossed to open it with the car running and heat on max defrost?

[j cAT]

Originally Posted by lokizan2

OK thanks i will replace the thermostat tommorrow, and could you tell me how exactly to bleed the system. i know where the bleeder screw is but am i suppossed to open it with the car running and heat on max defrost?

the main problem here is low coolant no leaks.
with low coolant you will not get heat. also the temp guage does not work. if the engine running and coolant bubbles out the fill spout this is usually exhaust gas from a heaD gasket leak..

you must pressure test this system to find leak. replacing the thermostat is not going to find a leak.

dexcool is used in these engines. it is possible a non dexcool coolant was used. this then corroded the gaskets and metal to create coolant system failure. insufficent coolant concentration in cold freezing weather can damage and cause very strange coolant issues.

the heater is always having coolant flow thru it,,winter/summer heater on or OFF !

open bleed screw when engine cold slightly , allow air to come out slowly. use a cloth to capture the coolant..continue till engine at temp and coolant is full.

[lokizan2]

What i dont understand is how can the low coolant light come on and no heat come out, then the low coolant light goes off and i have heat all in the same driving cycle. If the coolant is low then how does it keep refilling itself, the level of the reservoir appears to be the same after i drive and check it. Thats why i thought that it might be the thermostat starting to stick or something, since it appears from the temp gauge that the tstat is opening..its just taking longer that usual. It just seems weird and it has been freezing here in chicago for the last month. Well i guess i'll just replace the tstat and if that doesnt work take it to the dealer for diagnostic. Im praying its not the head gasket, really dont have 800 bucks or whatever it costs laying around

[lokizan2]

Im sorta a noob to auto repair so forgive me, the first time to took the rad cap off while engine running the car was hot already. i just went out there while the car was cold took the rad cap off and started the car, i saw no bubbles or gushing fluid out of the rad this time. Also for my car to be showing these low coolant lights, the coolant was damn near filled in the radiator already!! I put a little bit in there to bring the level to the top of the rad. If the low coolant light is coming on should the fluid level in the rad be whey down there in the radiator?

[maxwedge]

The coolant sensor could be bad, unrelated to your present problem, or air bubbles are fooling it.

[j cAT]

Originally Posted by lokizan2

Im sorta a noob to auto repair so forgive me, the first time to took the rad cap off while engine running the car was hot already. i just went out there while the car was cold took the rad cap off and started the car, i saw no bubbles or gushing fluid out of the rad this time. Also for my car to be showing these low coolant lights, the coolant was damn near filled in the radiator already!! I put a little bit in there to bring the level to the top of the rad. If the low coolant light is coming on should the fluid level in the rad be whey down there in the radiator?

don't go to a dealership with a car this old !

you will find many recommended auto repair shops that can fix this.

lets say it is the head gasket . the exhaust gases get into the coolant cause it to bubble/air the water pump pumps water not air. this then causes a very weird coolant / heater operation.

you or the repair shop must pressure test and find the leak . loosing coolant , cannot see where its going correct ? this is the first step , in locating the cause of your issues.

coolant fill bottle still full , this is usually what happens when gases are injected into the coolant,or the connection to the radiator is defective/leaking.

[mcmalloy]

you said the over flow was full , if its up to the top, you need to drain some out until its at the proper line, after that crack the bleeder valves for the cooling system until antifreeze comes out

[lokizan2]

Problem somewhat solved, i have a neighbor that is a mechanic and he came over and looked at my car for me, he noticed the both the upper and lower rad hoses were collapsed...said that it most likely was the rad cap. i went and got a new rad cap and have driven the car about 40 miles total and the low coolant light doesn't come on anymore, the car warms up like normal and the temp gauge stays pretty steady. the heat comes on but it takes a while for it to come on, like the temp gauge will show that the car is warm but it still wont blow out warm air, after about 10 more mins the heat comes on and stays on. not sure if this is a serious problem in disguise, but almost all of the other symptoms are fixed now. all over a 4 dollar rad cap!!

[j cAT]

Originally Posted by lokizan2

Problem somewhat solved, i have a neighbor that is a mechanic and he came over and looked at my car for me, he noticed the both the upper and lower rad hoses were collapsed...said that it most likely was the rad cap. i went and got a new rad cap and have driven the car about 40 miles total and the low coolant light doesn't come on anymore, the car warms up like normal and the temp gauge stays pretty steady. the heat comes on but it takes a while for it to come on, like the temp gauge will show that the car is warm but it still wont blow out warm air, after about 10 more mins the heat comes on and stays on. not sure if this is a serious problem in disguise, but almost all of the other symptoms are fixed now. all over a 4 dollar rad cap!!

in post #8 I stated "when coolant fill bottle still full , this is usually what happens when gases are injected into the coolant,or the connection to the radiator is defective/leaking ".

I would guess the leak was at the radiator cap.

coolant leaks out at radiator cap , bottle stays full because leak prevents coolant in bottle , from being sucked into the radiator..