While my car is at idle I get regular operating temperature. As soon as I give it has and start to climb those rpms it slowly starts heating up. The second I quit working the motor (stop giving it gas) the temperature slowly drops.

At times while driving my temp will hit high all the way to the red. Then drop down rapidly to normal operating temp.

I'm leaning towards my water pump being bad, or only working intermittently.

Has this happened to you? Other causes?

I pulled my covers today and saw coolant everywhere. Just not sure where it's coming from. I noticed the cap wasn't all the way sealed to my reservoir. Maybe with the temperature that overflow started boiling and slowly spewed?

I got a check engine light just barely.
But as soon as I made it home and popped the hood and locked around I started my car again to see if I could find where it was leaking. The lights were off and couldn't pull a code anymore.

Any ideas are appreciated.

 

Have not heard about this issue. Should bring bring to shop ASAP I think water pump.

 

I was begging for a stored code. Ran it last night. Got p0117. Coolant sensor fault. Was thinking it was the pump. Then got to thinking, they typically work or don't. They're not so much intermittent to my knowledge. I just haven't had this Lexus too long so I'm new to all this. I'm going to replace the thermostat today and see if that doesn't fix it. I've got 90k on the motor. It could be the pump still. I'm just praying it's not gonna be that head gasket.

 

I also am getting back pressure. So that's why I'm leaning towards that thermostat being stuck till the coolant starts to boil. Then it finally breaks and allows the Coolant to pass through. I wouldn't get back pressure if the pump wasn't working, correct?