I have a 2000 dodge neon es. I have recently rebuild the cylinder head due to a low compressed cylinder 3. While having the cylinder head off, I replaced the radiator, water pump, thermostat, all seals and gaskets, belts and other parts. After putting everything back together, i drove the car on the highway for 6 hours, the whole time my temp gauge would read cold... When i pulled over, the engine temp increased to operating temperature. My first thought was the thermostat was stuck open. So i drained the coolant and took out the thermostat, and infact it was stuck open. I replaced it with a new one. 4 days later i was having the same problem but the temperature wasnt all the way down, just a line above cold. It takes it long to warm up, any idea???

 

Is the spring side of the thermostat facing the eng block? Also if you have a lot of air in the coolant system it will act weird. But it had to have gotten over 180 or what ever is stamped on the thermostat for it to lock the safety open.... I for one don't like the locking thermostats, even though they are fail safe when it comes to saving your eng.

 

If the t-stat was installed backwards it would overheat very fast.

My guess is either air or you bought another faulty t-stat.

If the top hose is cold and the bottom hose is hot, then you need another t-stat.

 

i drained the coolant. took out the t-stat and flushed the whole system. when i took the t-stat it was not stuck open so it functions. i put everything back and filled it up to spec. let it run with cap off to bleed the system of air. it still does not function right. it gets to operating temp when im idling, but once im moving the temp goes down halfway between 0 and operating temp.

 

So you're saying it runs between cold and the first dash on the temp gauge?

 

Hi I’m wondering if you ever found the answer to this I’m having the same exact problem to a t my gauge won’t go up to operation level and my cylinder number there is running 30 ib of compression and now it’s not starting unless it’s COLD like right in the morning or if I leave it for a few hours unless I go to crank it and hold the gas in all the way to the floor and I have to rev it for a few seconds other wise it dies could you please get back to me ASAP