2008 ES350 Overheating and heater only when revving engine

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Hello everyone,

Just bought a 2008 Lexus ES350 with the 3.5l V6 engine, but the previous owner said that it starts to overheat, so I assumed that it was the water pump or thermostat since it has not been changed since new (currently sits at 175k miles). Symptoms that I am experiencing is that there's no heater, but if I rev the engine at idle the heat comes through, but when I start driving the heat becomes cold and I start to overheat. I just changed the water pump and thermostat with OEM parts and tested the thermostat as well in boiling water. However, before I did all that, I drained the radiator to see if the fluid was brown or if it was clogged. Fluid was red/pink and it drained just fine. Also have dealership records of it being services regularly with coolant drained and flush for about 30k miles or so. Burped the system, but still overheating, but the radiator was cold to the touch. I am at a lost.... Maybe I'm not burping it right? I unscrewed the nipple valve in the back and used no drip funnel with a tube that connects the two. I can't seem to get the coolant to come out in a solid stream (only air bubbles) but I kept the revs at 2-2.5k for about 15-20 minutes. I felt that its kind of long for burping? Please let me know. Thanks ya'll!
 

Ian Schmidt

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Did you verify somehow that the new water pump is working? Because that all sounds like it's not, and for the last 5 years or so "NEW means Never Ever Worked" has been true an alarming amount of the time. Although OEM parts generally fare a lot better.
 

Ian Schmidt

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Huh. I would've thought that the coolant would've been discolored in that case, but glad you figured it out!