OK got her out the garage finally. and she runs a lil smoky but o-k for around 5 mins. then coolant light comes on. i look at temp gauge and its fine so i come to the next stop sign and stop and coolant light goes off. continue and look down to see heat reading at the white bar before hot. oh **** take next left. waiting for traffic to clear to make the left hander into a school parking lot, heat returns to halfway point. pull into school anyways and pop hood. look in and nothing is seriously out of place jsut normal symptoms of new motor. see that the over-flow resivoir for coolant is coughin up coolant onto something hot causing steam. look under front bumper and pull back dustshield to see a crack where the neck meets the tank. go back to look at heat level and shes back up to the white line before hot. then coolant light comes on. i blip throttle and coolant light goes off. car is idling at 1,300 so i turn her off to cool down. come back later and try again and this time shes idling at 1,700 WTF?? O-K shut her down for the night after frustration sits in. could air pockets in coolant system cause thermostat to say engine is too hot?/ light to come on. whats weird is that when the gauge read too hot the coolant light was off. then when coolant light would come on it was in the acceptable range. HELP argh... i hate this damn car. my 240sx is more reliable at this stage in the game... grrrr

 

Your coolant seal has failed and exhaust gas is leaking into the coolant system. It's time for a rebuild.
Do a search for coolant. you'll find all the answers you need. Sorry man.

 

how can it be my coolant seal?? i just had this motor rebuilt! it has less than 150 miles on it. its gotta be sumthin else

 

Check your coolant caps. If they are worn, they can cause problems. It might not be your problem, but it would be a cheap way to get started.

Also, make sure you burp the system:

https://www.rx7club.com/forum/showth...threadid=96029

 

In that case you didn't burp the coolant system properly before you started driving.
Did you do the rebuild yourself? If not then who ever rebuild your engine didn't finish the job. There is a lot of air that needs to be purged with a new engine. Heater core, block, radiator and hoses all have air in them.
Warm up the car with the radiator cap off (this is where a radiator fill/burp kit is extremely helpfull) and the heater on full blast. Run the engine untill warm, occasionally squeez the lower radiator hose a couple of time. This will help speed up the process of getting rid of air.
When there if air in the system the water pump will not function properly (since it's pumping air instead of liquid) and will cause overheating. The ast will help, but not if there is too much air in the system. With a new engine install, it typically takes several hours to properly purge the coolant system.
You had mentioned the stock temp gauge was almost pegged to the top, that is not good. Unless you have linearized your gauge, the engine is already overheated. Let's hope it wasn't long enough to have done any serious damage. Good luck.