Hello all, we own a 2007 Toyota RAV4 3.5L V6. It has 450,000km. Up in Canada land yes. 😛

Recently we started having overheating issues. Temp gauge running very hot in stop and go traffic, and coolant boiling over. 

We replaced the thermostat, and that has not fixed the issue. The water pump was also replaced in April. 

Most recently tried purging any air in the system (using the purge valve to funnel method), and had to stop since the coolant boiled out of the reservoir. I noted that the coolant coming out of the purge line into the funnel seemed to be at a low flow rate? 

It seemed like the coolant system is not getting proper circulation? 

Could it be a faulty thermostat? if that even was the issue in the first place? We kept the original OEM just in case. 

Or maybe something to do with the radiator itself causing a blockage? **

Is there anyway to test the radiator for flow? Can it be cleaned? 

What else could it be? 

Thank you all.