Idle Overheating problem

[blackrms13]

When I first start up the car from cold, and let the car idle before the car fully warms up, or drive the car a little and let it idle
the engine will warm up to the normal temperature then shoot all the way past hot according to the cluster

the top radiator hose is hella hot
bottom is cold
overflow tank is almost boiling
thermostat is near new(nismo one)

but if i shut off the engine and let it cool for a bit
then start up the car, thermostat will open and everything will be normal

and if i start up the car and drive normally(whether use a/c or not), the car wont overheat at all

whats causing the thermostat to not open when i let the car idle to warm up?
water pump?


91 S13 with 95 OBDI KA24DE pretty low mileage
new koyo oem copper radiator
nismo t-stat
water pump is unknown, i assume OEM one from the factory?

[lazysk8er2]

hows are the hoses maybe clogs or something?

[CrazY kouki]

u should make sure u have no air in the system and if it does just find somewhere uphill and run the car so the air goes to the top without the radiator cap on

[gotspins13]

sounds like you only left us a few options, water pump or check your hoses, maybe your radiator?

[lazysk8er2]

sorry for the half assed reply my gf was yelling at me...

ok is there heat coming out of ur vents?

check the system for air like mentioned above, check the hoses if they are going to the right places and if they are clogged in any way. check the return line to the tank. try replacing the thermostat with an oem. water pump also mentioned above. maybe even the heater core might be clogged as well.

[blackrms13]

hows are the hoses maybe clogs or something?

i dont think so, ive replaced both top and bottom radiator hose when i replaced the radiator

u should make sure u have no air in the system and if it does just find somewhere uphill and run the car so the air goes to the top without the radiator cap on

i 80% sure theres no air pocket, but i could be wrong

sounds like you only left us a few options, water pump or check your hoses, maybe your radiator?

hmm...ill look into the water pump

sorry for the half assed reply my gf was yelling at me...

ok is there heat coming out of ur vents?

check the system for air like mentioned above, check the hoses if they are going to the right places and if they are clogged in any way. check the return line to the tank. try replacing the thermostat with an oem. water pump also mentioned above. maybe even the heater core might be clogged as well.

heat is coming out no problem
ill try bleed the system again, and see what happens....

thanks people for hte response