The Overheating Camry That Is Not Overheating? Help

I have a 2000 Camry LE 4 cylinder with approximately 106,000 miles on it. For the last year, the temperature gauge has not stayed at the midpoint where it normally ran for the first 6 years I had the car. At first, if I turned on the air, it kicked in the fans and the gauge went down- initially, the problem was intermittent, but never stopped me from taking a vacation in Utah. About a year ago, I changed the timing chain and did the water pump and thermostat and most recently- about 2 weeks ago, I changed the radiator, which was cracked, another thermostat and all 3 sensor switched- the fan switch at the bottom of the radiator and the coolant temperature sensor and switch on the right side of the engine block where the hose from the top of the radiator comes in.

Today, I had a radiator shop test the car. According to them, the car is not at all running hot- they tested it with a laser sensor at the thermostat hose, the radiator and the return hose into the block. According to them, their final word today was that it is just the temperature gauge that is not functioning correctly- although yesterday they thought it was a bad fan switch and earlier today a bad thermostat. But since I changed the sensors…what could be causing this? I have also noticed that when the needle, which now heads up to about a half inch from the red and stays there, it will come down if I turn on the heater with the heater fan on.

What has remained consistent with the problem, since it started a year ago is that the radiator fans will ultimately come on by themselves, it just does so very late when the needle is close to the red- only now, it is closer to the red than I have ever seen it, even though, the radiator shop and I don’t believe it is actually overheating. I would like to get this fixed, but by somebody who has at least a notion of what is going on and at least a theory as to what they are going to try- that I already haven’t. Any suggestions would be very much appreciated. Thank you for your time in considering my request.

Leonard Isenberg


cell 323.383.7805

First of all, I don’t know that I’d be too keen on posting my phone numbers on a public forum like this…

Second, do you ever notice any coolant missing?

 I would suggest the only way you are going to really find out is to add a temporary temperature sensor to figure out what is really going on.   I suspect it is a gauge/sensor issue.  You could remove the gauge sensor and put it in a fluid that you heat up while it is still connected to the car. Measure the output and watch the gauge while the fluid is heating up and is being measured by a separate device and see what is happening.  

Frankly I would not worry about it as long as you are comfortable that it is not really over heating and that the gauge is not showing over heating.  They don't make the gauges very accurate.  They are just trying to tell you that they are cold warm or hot, and it is doing that don't worry.

No coolant missing- the system is now virtually new.

Thanks. The new external temperature monitor gauge might be the cheapest way to verify what the temperature is at any time and to assure myself that it truly isn’t overheating. The reason I just don’t leave it is that it stayed rock solid at the middle for the first 6 years I had the car and I think that what is going on must be knowable. It scares my wife and daughter to see it just below red…me too, even though I know the laser shows me that the actual temperature is actually okay. Thanks again.

The one thing that sounds suspicious is that the temperature gauge will drop if you turn on the heater with the heater fan on. You are effectively adding another radiator to the cooling loop to remove some of the heat. My first theory is that you may have bugs or debris on the exterior of the radiator, but you said that you replaced the radiator. However, there may be some reason why not as much air is circulating around the radiator. The radiator company probably tested the coolant flow in the shop. Things are different on the highway. Has some piece on the front end that would direct the air flow to the radiator been removed or possibly fallen off? I remember one case of an autombile manufacturer having problems with cars that would overheat in some states and not in other states. The terrain of the land was not a factor. The overheating would occur in cars sold in one state and not occur in cars sold in a contiguous state with the same terrain. The cause turned out to be the front license plate. In states that required a front license plate, the cars would overheat. Somehow the design of the grille caused a front plate to change the airflow pattern. These cars didn’t have the problem in states that issued only one license plate for the rear. Did you put a vanity plate on the front of your car? (I know this sounds far out, but you seem to have eliminated the common solutions). If you ever find the problem, I’ll bet it has something to do with the way the air circulates through the radiator.

When the radiator shop tested the temperature with a laser temperature tester, the radiator and both hoses showed that the car was running perfectly normally in terms of coolant temperature- it is only the temperature gauge that mistakenly tell you that you are close to the red. As best as I can figure, the sensor is giving the correct information to the computer, which is giving the wrong info to the gauge- maybe it is best…and less expensive to put in a second after market coolant temperature sensor that reports directly to the driver.

Has the system been checked for exhaust gases leaking into the coolant? It sounds like you may have a headgasket leak.