Overheating "93 300

[Cher]

My 93 ES 300 started overheating yesterday while driving in traffic. It gets hot while idling or driving slow and cools back down almost to normal while cruising at speed.

I checked coolant level. It is OK. And no leaks.

I checked fan. It is spinning at idle.

Could a bad thermostat cause this? I wold think if it was bad, it would also overheat at any speed?

Water pump bad? but not leaking at drainhole? Would this cause it to overheat only at slow speeds?

Thanks for any suggestions.

[SAFRO.COM]

Cher what your problem is could be the ones you listed. How often do you flush your cooling system? the thermostat may be the issue, it is probably getting stuck. I have seen water pumps that have broken fins, the fins that pump the water can break off. Take it to a toyota or lexus dealer. Ask for a mechanic to help you, you may get a quick and straight answer there. good luck

[Cher]

Cher what your problem is could be the ones you listed. How often do you flush your cooling system? the thermostat may be the issue, it is probably getting stuck. I have seen water pumps that have broken fins, the fins that pump the water can break off. Take it to a toyota or lexus dealer. Ask for a mechanic to help you, you may get a quick and straight answer there. good luck

Thank you. The coolant was changed less than a year ago when I needed a new radiator due to a crack in the plastic neck. I can't really afford to go to a dealer and was hoping my dad could fix it.

[Alexxus]

I have a '92 es300 and it was overheating so we took it in for a test. They said one of the hoses were bad and it was replaced. Since then it doesn't overheat and the temp needle stays in the middle of the gauge (typically).

There is this long steep hill where I live and I drove up it last week. Upon getting to the top, I saw the temp rising faster and faster toward red (H). When I got to the top of the hill, I pulled over. Nothing was steaming or leaking, just hot. I let it cool down and everything seemed fine. I tried it a second time and the same thing happened.

Everywhere else I drive it's okay, except that one big hill. Does anybody know why this would happen?

[busoptr]

I have a '92 es300 and it was overheating so we took it in for a test. They said one of the hoses were bad and it was replaced. Since then it doesn't overheat and the temp needle stays in the middle of the gauge (typically).

There is this long steep hill where I live and I drove up it last week. Upon getting to the top, I saw the temp rising faster and faster toward red (H). When I got to the top of the hill, I pulled over. Nothing was steaming or leaking, just hot. I let it cool down and everything seemed fine. I tried it a second time and the same thing happened.

Everywhere else I drive it's okay, except that one big hill. Does anybody know why this would happen?

It could be your oil has a little coolant in it, but just too little that you dont detect any coolant missing. My 2 cents.

[Alexxus]

I have a '92 es300 and it was overheating so we took it in for a test. They said one of the hoses were bad and it was replaced. Since then it doesn't overheat and the temp needle stays in the middle of the gauge (typically).

There is this long steep hill where I live and I drove up it last week. Upon getting to the top, I saw the temp rising faster and faster toward red (H). When I got to the top of the hill, I pulled over. Nothing was steaming or leaking, just hot. I let it cool down and everything seemed fine. I tried it a second time and the same thing happened.

Everywhere else I drive it's okay, except that one big hill. Does anybody know why this would happen?

It could be your oil has a little coolant in it, but just too little that you dont detect any coolant missing. My 2 cents.

How could I check if that's the case?

I checked my coolant, and it's been at the same level since last month I checked it.

[byf43]

My 93 ES 300 started overheating yesterday while driving in traffic. It gets hot while idling or driving slow and cools back down almost to normal while cruising at speed.

I checked coolant level. It is OK. And no leaks.

I checked fan. It is spinning at idle.

Could a bad thermostat cause this? I wold think if it was bad, it would also overheat at any speed?

Water pump bad? but not leaking at drainhole? Would this cause it to overheat only at slow speeds?

Thanks for any suggestions.

I just had the same problem with my '93 es300.

I thought that it was water pump; thermostat or radiator cooling fan (which was making a little whining noise, like a bad bearing).

Engine would start overheating when sitting in traffic, but, at speed, the engine was running normal. (At speed, the air across the radiator is enough to strip the heat out of the coolant!)

The repair shop said that the radiator cap (both) were bad. (Springs getting weak.) $65.00 and I was on my way.

The car started overheating the next day, so, I took it back.

After tests. . . .

It turns out that the A/C 'cycling switch' is/was defective.

For the hydraulic radiator cooling fan to spin at maximum speed, the 'cycling switch' has to open the solenoid completely, so that maximum hydraulic pressure will spin the radiator fan faster.

"Cycling switch" was $81.00. Vacuumizing a/c system to install switch and then re-charge a/c was $161.00.

Engine is now running very cool again.

EDIT: I had to take my es300 back to the shop because of a check engine light. Problem turned out to be Oxygen Sensor (Code "21") Left bank - Main Sensor. Replaced.

While repair shop is test driving this car, it starts behaving like the OP's car.

I've had radiator caps (both of them) replaced, a/c cycling switch replaced, and two hoses.

The service writer called me yesterday and said that they did more tests, and the found carbon monoxide traces in the coolant. (How they did this. . .???)

Bottom line. . . . Cylinder Head Gasket on front (left) 'bank' of engine is blown.

Repair shop is replacing head gaskets, pressure testing heads (no charge), replacing timing belt (no charge), water pump and thermostat (parts charge only) and the grand total with the Oxygen Sensor replacements - $1800.

The original charge for Oxygen Sensor was $336.

Ultimate bottom line. . . . the overheating problem that the OP is describing COULD be a blown head gasket.

[Ray92es]

My 93 ES 300 started overheating yesterday while driving in traffic. It gets hot while idling or driving slow and cools back down almost to normal while cruising at speed.

I checked coolant level. It is OK. And no leaks.

I checked fan. It is spinning at idle.

Could a bad thermostat cause this? I wold think if it was bad, it would also overheat at any speed?

Water pump bad? but not leaking at drainhole? Would this cause it to overheat only at slow speeds?

Thanks for any suggestions.

could be a bad water pump. Mine went at 175k. so it was pump and belt time. And yes, the pump does go bad without leaking. I don't know how long mine was going bad until that day I got stuck in traffic due to major accident. Depending on how early a 93 you have, it may be a hydraulic fan. In that case, check to see if your power steering fluid is low. The fan may spin at idle but not have enough fluid to spin at higher speeds.

[byf43]

could be a bad water pump. Mine went at 175k. so it was pump and belt time. And yes, the pump does go bad without leaking. I don't know how long mine was going bad until that day I got stuck in traffic due to major accident. Depending on how early a 93 you have, it may be a hydraulic fan. In that case, check to see if your power steering fluid is low. The fan may spin at idle but not have enough fluid to spin at higher speeds.

Items of note.

1. The engine cools back down when driving at speed, so, apparently, the water pump is pumping the water from the radiator, through the engine.

(The heat is stripped from the coolant because of the air flow across/through radiator, at speed, but not while sitting - no air flow and heat convection.)

2. If I'm not mistaken (I'm not a pro or expert on the es300, by any stretch of the imagination) the es300 had a hydraulic radiator fan motor in '92 and '93. Maybe the '94, also.

I was very concerned that the hydraulic fan motor had gone 'south' in my case, whereas, it was the a/c cycling switch.

One technician said that the hydraulic fan motor technology in 'theory' was good, it was the implementation and electronics that were poorly executed.