Hello there, I have a 2008 Lexus IS 350 and when I put the foot down to do a full 100% acceleration, I notice the coolant temp drop down then going back to operating temperature. This only happens when I do a full 100% acceleration. Wonder what could the issue be? Thank you.

 

On a cooled down engine. Check the coolant level at the radiator cap. Is it low on coolant?

 

Coolant is full when I checked and so is the reservoir tank as well.

 

You probably have air bubbles in the cooling system, make sure it's bled properly. If you've owned this car for a while and this just started happening, then you might have an issue with the water pump too. If you just bought this car and don't know it's maintenance history, then it's probably just air in the cooling system.

 

Ok will check for air in the cooling system. Bought the car last year and saw that the previous owner changed out the waterpump and thermostat. Thank you.

 

Oh OK, then yeah, they probably didn't bleed it properly. Not a big deal. Good luck!