Overheating... again

RIght so heres the breakdown...
420a, new aluminum radiator.... good hoses, it does have liquid in it...
This guy was overheating on RUSH hour, got in the freeway it cooled down... i still stopped at a gas station trying to refill the damned thing (turned out it did have water) and apparently issues was solved.

TOOOday... i had a low tire... so i filled it up... i got into the car and it was hot again... i was like wtf?! i drove home and it was fine on the way home... i stopped on the driveway.. let it idle... started overheating... revved and the temp went low... let it idle again and it rose one more time....
Am i havin a problem with the water pump? the thermostat?! why is my heat going nuts?!

Is your fan coming on?

change your thermostat. my old RS did the same thing and i couldnt figure it out untill my friend said to check it.

yeah the fan comes on... well 1 of them... my guess is that the other one is for the a/c right? and how about a 180 failsafe thermostat? i think it has never been changed by the previous owners

I still think its your waterpump. I have a 420A been in the same case as you sitting in traffic with A/C on. A/C went warm temp rose. On the highway temp fine, at a stand still temp high

No a/c... in my car there's only a/c if its hot outside and theres a girl in the car... and about the water pump... well could be a possibility but when i was idling the car withouth the radiator cap a while ago i could see the water circulating... so... i think im gonna go with the thermostat for the moment.... any possibility that my new radiator could be toooo small? or something like that?

EDIT: how much of a common issue is this on a 420a?

no, guaranteed its your thermostat. mine did the exact same thing. when you drive it cools down, or rev it when its stopped. but when your at idle the temp sky rockets. if it was your pump, it would just over heat, moving or standing still.
 
those thing got kind of a fail safe when it breaks, your car can still cool down when you drive, so its like a warning when it happens so it just doesnt cause major damage. trust me i come from a family of Master Tech's

lol.. thnx for the info then... im still gonna change the thermostat cuz i dont really want to see the freaking nieedle going ALL the way to the top.... it gets me soo stressed out... but yeah.... when you drive it cools... you rev it cools... but idle... man feels like im gonna blow the engine!!

i have the same problem with my rs and i have no clue what it is

try changing your therostat first and go from there.

Like what tjbiker031 said, replace the thermostat first.  Its cheap and easy, easier then a water pump lol.

WAYYYY easier.... i got a new thermostat... cheap on though -_-..... its a 195f one... ill try to change that... and if its actually the problem well im gonna be saved and ill spend more on a better one later on...

i just read on the other similar thread for this... the one labeled problem.... so stiff rubber hoses mean i blew the headgasket?! o_O because the one that goes from the radiator to the engine is pretty much swollen... but that coul also happen if the thermostat is closed shut.. right?............Right? 

Just do a compression test, I wouldn't trust a swollen hose to diagnose my car.  I have seen a stuck thermostat make a coolant hose swell like you wouldn't believe.

LOL.. allright... well im waiting for the silicone to dry up so i can go for a test drive... im gonna give it an hour or so... i took a few pictures just for a diy for newbs

F*CKIN POS!!!!! i changed the thermostat and still SAME behaviour!!!!.... its a new one and i dont think that the fact that is 195 could make that much of a difference!!! wth is going on with it?!

Check your PMs KD.

Thank you john!

i say check your water pump it may be more work but you don't want to have to do it when it breaks.. that can get spendy though replacing extra parts and such like the timeing belt your accessory belts timing belt tensioner (possibly). 

thnx for the advice.... i just got mad shoved my hose in the radiator and give it a full blast.... i also did that on the thermostat... and that seemed to solve the issue now.... but i will be replacing belts and checkin on the pump just to be 101% sure... thnx guys... if anyone wants a detailed how to with pics on how to change the thermostast lemme know (sorry 420a pics only, but i dont think it can be toooo different on the 4g63)

Did you run the motor KD?  There are small passages that the coolant goes through and if there is any debris it may have clogged a passage or two.  Flushing the cooling system with the motor running allows more pressure than what the hose can provide to possibly flush sediments or the likes out.  Oh and a swollen hose should be changed out if you haven't already bro.  Pressure is lost to swollen and soft flexible hoses.  Also make sure that when you refill your system to allow the bubbles to escape.  That is very important because the bubbles will cause cooling issues, since air doesn't transfer heat as well as coolant or water.  Another thing is to keep the resevoir above it's min line.  That resevoir keeps air bubbles out by allowing any overflow to escape and then fills the rest of the system of what it is missing...then the cycle continues until there is no longer any overflow. 
A vacuum seal is important in this system, so also check your radiator cap or just replace it.  Air can enter through there too if the cap's seal is worn out and can no longer keep the seal.
Oh and water alone is fine for troubleshooting purposes, but I don't recommend it alone since it evaporates rather quickly (hence the oily compound in the coolant).

Yeah, thank you very much john once again... one thing i noticed is... when i was running the engine capless a lot of bubbles started blowing up after i shoved the hose down the radiator... i waited for a few til all the bubbles were gone.... i refilled the reservoir, sealed the radiator cap as tight as i could and turned the engine again.... now its running trouble free.
Its funny how such lil things can cause such and issue, but im gald is solved now and that i did it by myself with you guys help... im saving up for taiwan and cant really spend on mechanics and stuff like that (thats why i dont mind having a 420a... suppossedly a lil bit more reliable... but how reliable can a 10yr old car be haha).
Tomorrow i am getting some nice antifreeze =)

I wonder if there was just a bubble that caused the issue.  Bubbles can also cause flow problems.  It's very similar to air turbulance on an airfoil where the turbulance causes poor airflow over the airfoil.
Anyhoot, glad you're all good bro!

yeah... thnx for the help =) you know... i still have to fix the blinker issue but ill leave that for later lol... im just gonna sleep right now... im tired and pissed as you can see on the other thread lol... and you should too... its late haha