vkriss

Hello
My 2000 ES300 is taking too long to warm up and heater only blowing warm air for first 15min or so. The temp gauge is going little low on highway speed and staying at normal with city driving. I also feel like engine lost some power and running little rough. There are no codes in ECU. What might be the problem?

HomerJay

Check the cold coolant level by removing the pressure/radiator cap. Should be filled to the top of the neck. Do not assume coolant level is correct by only checking the recovery tank.
If the level is correct, the thermostat is likely bad and should be replaced.

mnewxcv

pretty much this.

vkriss

I Just hooked up scanner and went for a 2.7 mile drive (city driving & engine idling for 10min before the trip ). When i check the live data, the coolant temp reached 169-171F by the end of the trip. What should be the normal temp?

EDIT: coolant is full

HomerJay

Sounds good so far, an OE thermostat is rated for 180F. I would suggest a longer run time of at least 30 minutes and monitor the data. Also check both heater hoses, they should feel hot to the touch.

daredeil95

Could be heater core? My pickup had a bad heater core and would produce no heat, I just replaced the heater core this past weekend and now I get heat within minutes of starting the truck. My heater core was leaking and steamed my windshield but, it will get rust inside it and clog the heater core itself. You could flush the coolant system and they also do heater core flush.

LeX2K

Temp gauge creeping down when driving on the freeway is a sure sign of a bad thermostat.

Koolaid54

based on what you are saying. it sounds like a thermostat. What is ambient temp.

Allow the vehicle to warm up to operating temps. let it idle, rev the engine, what ever you do. dont drive it. once the car is at operating temps. in park. turn on to high heat at max speed. monitor temps.
Now drive the car with max heat. monitor temps


if you see temps drop at all. replace thermostat.

terror83

My 04 ES330 did something similar. I swapped out the thermostat to an OEM one and now it reaches operating temp quicker and the temp gauge doesn't fluctuate.

vkriss

Ambient temp 48F. Took almost 20min to reach operating temp (180-183F). Went for drive with heater full blast, drove only a mile and coolant temp reduced to 172-173F.

Oro

Asked and answered, as L2k and Homerjay said, bad thermostat.

Oro

Koolaid54

replace the thermostat

Rolodon

I need some help on where the Thermostat is exactly located ? Follow the lower hose on right side of engine or upper hose on left ? Already bought a thermostat at AutoZone and was thinking I could figure it out myself what parts would you have to take off ? Any help would be much appreciated