[kurtdawg24]

Okay guys. I haven't posted here much but I am about start. I 04 sentra 1.8s 5 spd was on a drive today. I had been driving around town for a while looking for my friend when I noticed it. I immediately turned off the car and waited for it to cool down and took it straight home. I let it cook and felt the radiator cap and noticed the liquid was bubbling. Not too sure if this is normal as I dont normally feel that. But I took it for a drive later and it was fine except when I was at red lights. The gauge would shoot up and go down to normal. I haven't checked the fluids but the over flow is empty. Haven't noticed any leaking either. Could the thermostat be going bad?

 

[Black B15]

It certainly could be as simple as a thermostat. But it could be a number of things really. Are you sure the cooling fans are kicking on? Are you sure your head gasket isn't blown, allowing oil/coolant to mix?

If the overflow is empty, it had to go somewhere. I would certainly add coolant/water to your overflow once your engine is cooled down completely.
Start there to see if you are just low on coolant. I am doubting this is the problem, but you never know.

 

[i68k]

if your reservoir/overflow tank is empty, you most likely got some air in your cooling system. did you see your temp 'shoot' up/down relatively fast? air in your cooling system will cause the needle to change position relatively fast, without regard to actual coolant temp. if this is your case fill up the coolant, and keep an eye on it, as your motor may not be overheating. this also goes with your coolant bubbling, the air may have just been surfacing. there are 3 main ways for air to get into the coolant, you have a leak somewhere thats letting air in, your reservoir was empty and allowed air into the radiator, or your headgasket is blown forcing air into the coolant.

when youre stopping at a red light, does the temp rise slowly while your stopped, then slowly fall once you start accelerating? if the needle is going slow, you maybe actually overheating. in this case, youll want to check your fans are working, your coolant is circulating, you dont have a bad headgasket, or bad thermostat, etc.

once you filled it up, take it for a small drive, not too far, and keep filling the coolant reservoir, never let it get empty or air will get pushed into the cooling system.