Engine Cooling problem
1995 Lexus ES 300 6 cyl Front Wheel Drive Automatic 162000 miles
Hello, I have a 95 lexus es 300 that has a overheating problem. I bought the car from an individual a couple of weeks ago and he said he had placed a new radiator and thermostat in the vehicle. After driving it for the first time the temperature hand rose to half way as normal but after that it started to rise up towards the red. After limping the car home I raised the hood to see that it was steaming and boiling under the hood. The radiator did indeed look to be new but I went ahead and bought a new thermostat and had it installed just to be sure about that. I replaced the radiator cap also and had the coolant flushed and replaced with new coolant. After starting the vehicle it still would start to overheat the same as before and after trying the old trick of turning the heat on to help slow down the heating I found the heater is not blowing out hot air. Thought maybe a head gasket but the car is not steaming from the tailpipe nor is the oil cap milky looking. I am stumped as to what this could be any suggestions will be greatly appreciated. Thanks.
Did you bleed the system? After engine cools down, remove radiator cap and top up coolant if necessary.
While bleeding cooling system, it is recommended to turn the heater on. Run engine for a rew minutes and if coolant does not drop, close radiator cap and run for 5 minutes. Stop engine and allow to cool. Recheck coolant level in radiator and repeat process till no more air are trapped in system.
Did you check the cooling fan? Is it working correctly?
Cooling fan used for ES300 is hydraulic and related to the power steering system.
As to the heater not blowing heated air, if the cooling system has air pockets, it would not work correctly.
October, 19, 2010 AT 9:08 AM
Thanks for the reply.
Yes I did check the cooling fan it seems to be working properly, I added a little power steering fluid to the reservoir because it was low. The fan seems to increase in speed as the engine becomes warmer if that is indeed the way it is supposed to operate. Also how would I bleed the cooling system? Do I do it the way you mentioned in your post?
October, 19, 2010 AT 9:22 AM
Yes, the fan would work faster when the temperature increases.
Yes, perform the bleeding as described and monitor the coolant level.
October, 20, 2010 AT 6:32 AM
I bled the system as you suggested. There was indeed small and big air bubbles rising to the top of the radiator. After about 7 or 8 minutes though the coolant level suddenly drops and it starts to spit the coolant out of the top of the radiator. I immediately shut the car off. Also after further checking the top radiator hose was hot but the bottom radiator hose was not hot or even warm at all. I also found that the top heater core hose was hot and the bottom one was cool I checked because I was still getting no heat. What now?
October, 20, 2010 AT 7:00 AM
1. Remove radiator cap.
2. Top up the coolant.
3. Close the radiator cap and run engine for 5 minutes.
4. Wait for engine to cool down.
5. Repeat above till the coolant level is at radiator neck when radiator cap is removed.
The upper hose being hot whereas the lower is cool because the thermostat is not opening when there is insufficient pressure.
The lower heater hose being cool could be due to the heater water control valve not opening correctly.
Check the valve cable adjustment.
October, 20, 2010 AT 7:24 AM
So is the thermostat defective?
If I try this a few times and it doesnt work what does it mean then?
Could the heater core be bad and if so can it cause a car to overheat?
October, 20, 2010 AT 7:51 AM
It could be but when there are air pockets in system the thermostat might not work correctly as it has to be immersed in coolant. Perform the bleeding and if the overheating still occurs, then you need to check/test the thermostat.
December, 7, 2010 AT 9:16 PM
Replaced thermostat but still have the same problem. Also the car will not overheat while idling the temperature hand will remain at the half way point, but when the car is placed in drive and it begins to drive off the temperature rises and it will eventually oveheat.
December, 8, 2010 AT 6:52 PM
You wuld have to check for clogging in the coolant passages and a weak water pump.
January, 14, 2011 AT 1:04 PM
Turns out it was a bad water pump causing all the problems. Thanks for your help.