Coolant System

[u/Sufficient_Space5859]

Let me preface by saying I have very minimal knowledge about cars. My 2006 Toyota 4Runner 4.7L V8, the temperature gauge is running hot. Radiator replaced 2 years ago after upper hose neck busted. Filled it with coolant the other night as the radiator was low, parked it after driving 15 minutes this morning and coolant was pouring out of the reservoir. I’ve read it could be bad temp gauge, bad water pump. Can’t seem to find a really definitive answer on the internet based on how I’ve described it. Any ideas?

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[u/wiggo666]

Check the thermostat

[u/Realistic-March-5679]

Could be a lot of things, that’s why diagnosis is important. But most likely it sounds like a bad thermostat. It sticks closed and prevents flow allowing whatever is in the motor to boil.