1986mustanggt5.0

while im driving my 86 gt when its dead cold ill b driving then all of the sudden my gague shoots up to about around 210 to 250 it normaly runs about a 190 at the most then ill let off the gas and it shoots back to 190 and then nothing it just gets lik really ott then goes back to normal and its full coolant wut would the problem be?

motorman524

tstat mabe?
EDIT: or air in the system. have you recentally changed the coolant.

ddeaton66

+1

Mike93SVT

testthe radiator cap, that's if you're overflow fills up when it gets hot

1986mustanggt5.0

just changed the coolamt lik a month ago it did it before and after i did i thought that was what it was but its not i got a brand new thermostat and water pump there both not even a year old

88ragtop

I would check to make sure theres no air in the system.........burp it i guess you would say