help with a coolant problem

[KennyB01]

for the past month or so i have been having a problem with my coolant boiling out after i stop the motor. as long as it is running it is ok, not running hot or nothing, can ride all day but as soon as i shut the motor down it boils out of the over flow rumbles through the radiator like steam and i have to half fill it again. i did a presure test and it does not leak down so i am out of ideas of my own. thanks for any input from anyone.

 

[Bigg G]

Did you change or swap your coolant hoses or thermostat before the boiling issues started ?
If so is the thermostat in correctly ?
Did you try bleeding the air from the coolant system ?

 

[Swims350]

I would think maybe it's got an air pocket in it or too full? or even thermostat needs changed? Is it the stock guages? they could be wrong and not reading the correct temp. I'd look into a thermo cap or something to take the radiators temp. Alot of people drill a small hole or two in the thermostat to help bleed air from the system, others leave it running with the cap of then fill it up.

 

[KennyB01]

I would think maybe it's got an air pocket in it or too full? or even thermostat needs changed? Is it the stock guages? they could be wrong and not reading the correct temp. I'd look into a thermo cap or something to take the radiators temp. Alot of people drill a small hole or two in the thermostat to help bleed air from the system, others leave it running with the cap of then fill it up.

i have not had the truck long, it did not start untill about 6 months after i had it and i drive it around 120 miles everyday back and forth to work. i was kinda leaning towards the thermostat or the fan. the only reason i did not change the thermostat was because i had convinced myself that if it was that it would run hot while driving. but i will try that since it is not that hard of a job. thanks

 

[71 cuda man]

Yeah I'd start by flushing system replace thermostat & check cap.I don't know what year your truck is but some models have a bleed screw if your does bleed system to get air out.Another thing that will do it would be incorrect timing.