overheating problems?

welli have a 94 lexus es 300 and that is my baby, i give it a tune up every 3-4 months and a complete real GOOd tune up every year. just recently i was using the AC and the car started heating up. i drained the radiator and put in antifreeze and changed the radiator cap. there was nothing wrong withthe thermostat but i changed it aywas. the car started to heat up constantly every 20 inutes of running and it makes a sputtering noise as it speeds up. the oils in the car were checked and every seemed to be ok. last time it was overheating and it sounded like it was boilling. i noticed a hose under the manifold that was steaming. could it be the heater hose that was damaged? i know its not the water pump because there is no water leak under the car.. so what could it be? blown gaskets? piston problems?

You have a pinhole leak somewhere that is not allowing the system to pressurize and prevent boiling. Borrow a coolant system pressure tester from your local parts store and pressurize the system then look for leaks. Could be a cracked hose near the manifold and/or a pinhole in the radiator. After 15 years, a rad can only hold out so long. Hope this helps!

My 93 ES300 overheat and coolant starts to bubble in reserver "only" when my AC is on. Problem started last year, but since I don't have any overheating or leaking issue with AC off, never had a chance to pin point my problems. I have 70,000 miles and never had water pump, thermostat changed. But again, no problem driving for hours as long as my AC is off.
Does anyone have any suggestion is to where to check?
Thanks.:confused:

I am having the same issue with my 92 es300..i have already sent the heads to the shop..resurfaced..new lifters..head gaskets..new timing belt..new radiator..waterpump...thermostat..and still doing the same thing as yours when i drive..i am seriously pissed off with this thing..maybe if you have found anything you can let me know..my last resort is to take it to lexus dealer..been going on for about 7 months..thanks..

Try a pressure test on the cooling system. If it is boiling, then it is not holding pressure as it should. A test kit will pressurize the system and allow you to see any pinhole leaks without having to work on it while it is hot.

the sme thing is happening to my 96' es 300 it just started a couple days ago just smoke steam something im not sure but it started doing it on the passenger side under the hood then all of a sudden the car shut off and locked up

i have a 92 es300 and we just had the heads done about 8mos ago and it overheats with air on or off now, iv removed the thermostat and it still overheated. as far as i know the heads r in good shape iv even checked water pump and no leaks in that area, what else could there be i could check :uhoh:

Check to see first if coolant is circulating and that the system is full. Then check to find a leak by pressure testing the system using a test kit (typically available at your parts store on loan).

Second, check to see if the cooling fan is working. That fan is hydraulic not electric and runs using fluid from your power steering pump and system. Check the resistance of the solenoid valve that controls the flow into the pump at the fan's hub and the in-line oil filter that runs to the small oil cooler just above the lower air dam.

Hope this helps!

I have a 93 Es300 with 184k, I have been overheating after about 20 min of driving. It also lowers the temp when i rev it a bit. It also always runs a little hot. The fan blows and it kick up to high when the a/c kicks on. I also noticed the fan speeds up with wngine rev. Relpaced the radiator, water pump, thermostat and radiator caps. It passes the block test. I think i have now found the problem!!! It overheated today and I started it and reved it a bit while hot and the hydrolic hose from the ps pump to the fan was squirting a ton of fluid. I believe the connection on the hose where it goes from rubber to metal starts to leak bad at high temps. I am going to replace that and see what happens.

Your car has a hydraulic-operated cooling fan, using fluid and pump from the power steering system. Its speed is controlled by a temperature sensor and solenoid operated throttling valve. Increasing temps open the valve more allowing more fluid to flow to turn the cooling fan. Obviously, a major leak will keep the fan from running. Fix that and post back. Good luck!

Well got the fan high pressure hose is done>>>>>> On to the NEXT problem...... The car STILL overheats with the following symptoms;
-always has bubbles in radiator
-warms up quickly and stays at first line above half way
-fan speed increases with engine rev but not A/C
-I think it is the power steering pump which is very noisy during overheat
- Car drives for 30-45 min of city and hwy before starting to overheat
- Heater helps bring temp down, also acceleration
-Boil over in to overflow
-Heater sometimes wont blow hot until engine rev
-When hot upper rad hose holding a lot of pressure


Work done;
Radiator
Thermostat
Temp sensor
Water pump
Fan high pressure hose
Coolant system cleaner
Both rad caps



Tested with the block tester and it passed, bubbles came up in to the tester and the liquid never changed color. Left tester on for a good 20 min with revving the engine. I am wondering if the ps pump is failing, i am pretty sure the solenoid for the high fan speed is not working properly. I set up a very high speed fan blowing in to the grill during an overheat and it did not seam to do a whole lot.


I have a theory, is it possible the the intake gasket has failed, causing air in the coolant, causing the coolant to not circulation well, in turn boiling off valuable coolant? I am not sure why it passed the head gasket test i am told that is very accurate.


I have read a lot of problems similar to mine but of course most do not show what their solution was. Someone please HELP......

You can try a leak down test (a pressurized air fitting is screwed into the spark plug hole of each cylinder with both valves closed) to see if the head gasket has failed between the pistons and coolant passage. If you get bubbles coming up into the radiator from this, there's your leak.

If the power steering pump is making noise, then it definitely could be that since the pump also supplies pressurized fluid to the cooling fan.

Using the cabin heater is a common way to help an overheating car, since it really acts like a mini-radiator, albeit very uncomfortably so.

Sounds like it's not holding pressure. Maybe a leak in a hose. I don't think it's a problem with the radiator.

When toyota stopped using asbestos in there head gaskits around early 1990 a lot of windoms a lexus models had gaskit failure apparently later models mid nineties this was solved by using a different material as it ia a expensive exersize to replace both gaskits a lot b uy second hand units if you do are capable of doing yourself beware when removing water from block as even a small amount that leaks into bores can cause instant corosion