Radiator Filler Neck Replaced Car Overheats Now

[jmb15]

07 rx350 114,xxx sat for a week while the filler neck part came in; replaced it and car seemed fine. Left my house later and car started to overheat. I put coolant in it and the temperature regulated to normal; should I look for something else to fix or would the lack of coolant do the trick.

[scottq60]

yes...a lack of coolant would cause overheating, after all, it's the coolant that carries the heat away from the engine. There may also have been air pockets that had to work themselves out after replacing the filler neck. Just keep an eye on it.

[RX400h]

I don't change coolant (myself) anymore for two reasons:

1. Used coolant is considered hazardous waste and most auto parts stores don't accept it as they do used oil and trans fluid.

2. The bleeding procedures have become more and more complex.

If the cooling system is not properly bled of air or coolant is leaking then yes, the engine could overheat. Other causes of overheating are:

1. Bag or newspaper covering front of radiator (temp rises at any speed)

2. Thermal switch fails - fan doesn't turn on. (temp rises only during slow or stop & go driving)

3. Thermostat sticks closed ( temp rises at any speed)

4. Radiator or overflow tank cap does not adequately keep the coolant system pressurized (failed cap).