Hi, I believe my 2010 Lexus 450rx h has a bad thermostat. Is this a project that is reasonable to take on, or is it harder due to the way the car was built. I suppose I’m wondering how hard is it to access, and how much disassembly is necessary

 

I have not replaced one in my 450H so no first hand experience to share. [Replaced one on first gen and posted DIY there. RX are not drastically different, but you are on the right track to ask.]

Can you share what leads you to believe that you have a bad thermostat? 450 coolant warming is slightly different and its behavior is slightly different in cold environment. This is because 450 tries to reduce IC engine use. In winter there is a demand to heat the cabin and 450 even sucks heat from exhaust ducting. On top of it the IC engine needs extra fuel to reach optimum temperature. Any prior learning about thermostat has to be re-looked at in 450H. In simple words, 450H is not the ideal vehicel for extreme climates.

Salim

 

I recently had my thermostat replaced, somewhat pricey due to labor required to access it. 2010rx450h. The thermostat was stuck partly open, so car would not heat up properly.