Overheating 01 civic

I was wondering if someone has encountered this problem and what their solution was..............
The coolant levels are fine but the temperature gauge goes all the way to HIGH. After about 20 minutes of running the car it starts to spit out coolant out of the Reserve tank. When driving in the freeway the temp is normal but once I slow down in the streets it goes all the way up. I took the car to three mechanics. The first one said that it needs a new headgasket, the second one said it was the thermostat, and the third one said to replace the temp gauge. Also, the reserve tank is almost full, i have emptied it out and filled it to its proper level but it keeps filling up and spitting out the fluid when the car runs. What do ya think??
Probably my first step will be replacing the thermostat since its way cheaper than replacing the head gasket.
thanks in advance for any advice....

have you checked to make sure the cooling fan is coming on?

have you checked to make sure the cooling fan is coming on?

The fan does work. I asked a friend and he said to replace the radiator cap since it might be busted so I'll be doing that tomorrow. My girl was stuck in traffic the other day and the temp went all the way up to HIGH and she said she was like that for about 5 minutes!!! Do you think that could have messed up my head gasket??
Thanks,

they head gasket might be ok , but more times then not i have seen the head warp when it over heats like that , one of the best ways to check to see if you have a blown head gasket is to put a radiator pressure gauge on the car when it is cold and then start it up , if it starts to build pressure with in a min or so of running then i would say you have a bad head gasket , i would also do a compression check , hope this helps you out

they head gasket might be ok , but more times then not i have seen the head warp when it over heats like that , one of the best ways to check to see if you have a blown head gasket is to put a radiator pressure gauge on the car when it is cold and then start it up , if it starts to build pressure with in a min or so of running then i would say you have a bad head gasket , i would also do a compression check , hope this helps you out

Thanks for the reply. greatly appreciated. I had the thermostat removed 2 days ago and it stopped overheating, the mechanic said the car didnt really need it. Problem solved i thought.... however, when the car is hot the coolant still overflows the reserve tank. So this morning I took the car to a radiator shop where they inspected it for free (surprisingly). After an hour they informed me that I need a new radiator since there is a leak in the seal (or something like that) and that the head gasket wasn't causing the overflow in the reserve tank (I doubt that they did a compression check though, do you have an estimate of how much that would cost?). Supposedly it's better to just get a new one instead of fixing the seal. My car uses a Denso radiator which they want to charge me $155. They also said that I have to put in a new thermostat since not having it could mess up the radiator (another $16). To remove and reinstall the radiator it will be $73 and $50 to backflush. Anyways total would be like $330. Is that a good price, I think they're trying to overcharge me!!

After my civic was constantly overheating I had the thermostat removed but it still kept overflowing the reserve tank so I took it to a radiator shop where they determined that it had a leak and that i should get a new one. So before they began work on that I had them do an emissions check just to be certain that the head gasket wasn't warped due to the constant overheating. It turned out that they did detect gases coming out through the radiator so they told me i needed work on the headgaskets. They told me that I would also need a new timing belt since the headgasket was busted. Would I really need a new timing belt just cuz of the busted headgasket?? The car barely has 43.000 miles!! As far as I know it needs to be replaced at around 60,000 miles. Are they trying to take as much money as possible from me??

is your car leaking coolant? , if the radiator was bad it would be leaking , if it is go to your local parts store and check the price , i think you have a blown head gasket , only time i have seen a radiator make the overflow tank over fill is when it was clogged , it is up to you when you do the timing belt , i would do it now seens all the head will be off and your right there anyways , or you can spend more money down the road and have it put on in 20,000 , if you have anymomre ? just toss me a PM and i will try to help you out the best i can , hope this helps ya , goodluck