my car is overheating, not sure why...

[Black Thunder]

hey so my base-model 3000GT has been overheating for the past week. i changed the thermostat today thinking that would help, but it hasn't. the car is idling much higher than normal, about 1500-2000rpm. also there's no heat in the car, even though i had put coolant in the car. last week the temp gauge had stayed all the way up on H and when i pulled over, i saw smoke comin front the coolant tube and i saw coolant was on the ground. so now i'm wondering: would this problem be from the radiator or would it be the temp gauge sensor? thanks in advance!

[JasonY]

If you have no heat you have air in the system. Usually a recurring overheating problem after a bad overheat is from the headgasket letting go allowing the system to end up with air in the system.

You can pressure test the cooling system, u can rent the tester from autozone. You shouldn't lose any pressure even overnight. Assuming ur starting at a room temp and the ambient temp remains fairly stable.

Jason

[Alex3000gt]

Sounds like your coolant level has dropped to the point that the heater core hoses are filled with air.

Open the cap on the thermostat housing and see how much coolant it takes to fill up your system. If the system takes more than a drop of coolant, you were low and need to find where it is leaking from.

[mb3000]

As previously stated, I would pressure test the coolant system and find your leak(s)

Next, I would recommend a complete flush. Refill and burp the system and go from there.

[HydeDW]

While working that overheating symptom (advice rendered thus far viable)...you may want to also spin up some time and attention to pursue the high idle cause. I would start out first looking for some vacuum leaks on that issue. Maybe can add some additional detail regarding when that cropped up?

Dan
97VR4

[Black Thunder]

the high idle issue only started yesterday when i started the car. as far as coolant flush...when i took my car for inspection the guy almost failed me cause during gas reading the HC (hexane) was at 460 (he said its normally around 300 or so). he did a coolant flush and my car was running fine then. this was done on the 7th and the car was running fine till last week. i changed the thermostat yesterday but that didnt help. i have a feeling i may need another radiator but i'm gonna take it to a mechanic first and see what he says. i'm sure he'll do another coolant flush though. i'll keep this updated.

[IPD]

radiator cap. sometimes a $10 fix can make a world of difference.

[DocWalt]

radiator cap. sometimes a $10 fix can make a world of difference.

Try this! I was having issues pushing coolant and the cap was to blame. Also, make sure you burp the entire cooling system of air.

When the car is cold, top off coolant in the t-stat housing cap, then start the car and let the water pump circulate coolant, keeping it all the way topped off at all times until the t-stat opens and hot coolant flows through the entire radiator. Make sure it's topped off and replace the cap, and make sure the overflow tank is full. Shut the car off and let it cool down.

[Black Thunder]

well car is at the mechanic now so i hope it gets fixed...i took a video of the problem, should be visible for everyone: 3000GT overheating | Facebook