Greetings,

I have searched the forums, but am not sure if I have found my answer yet. A little bit about the problem:

I have a 2001 Camry, 4 cylinder with 160,000 miles. I noticed that over the last several months, the car seems to be running a bit warm. I'll try to describe as best I can.

After I start the car it takes a little more than 3 to 5 minutes or so to get to operating temp. After I have driven for a while, regardless of highway or in town, the temp gauge reads it bit hotter than it used to. If you imagine the gauge like a clock, with the 3 oclock position being the needle pointing directly in the middle of the field between cold and hot, my car will run at about the 3:30 position. It will warm to the 2:30 position and then I hear the fans click on and it drops back down to about the 3:30 position. When I first got the car, it was running at about the 4 to 4:30 position. I thought perhaps the Tstat was bad, so I replaced it, but I still get the same problem.

I have never had the car get to the red, nor has the needle ever gone above 2:00. I opened the rad cap when the car was cold and started it; cranked on the heater and waited. After it reaches operating temp, the coolant tends to expand out of the filler hole, not much, maybe a tablespoon, and then it levels out flush with the rim of the hole. The hose on top gets warm/hot to touch, but not to where you need to take your hand away. The bottom hose stays cooler, but after a while it gets warm. Not as warm as the top one though.

Maybe I am being overly concerned, but my Camry never broke the 3:00 mark on the gauge before, and I'd like to catch the problem before it gets worse. No leaks anywhere. Any suggestions on what I can do to rule out/in things?

Regards, Brenden.

 

1. you may have replaced t-stat with a high temp one. which is generally a power mod. but shows higher temp readings.
2. if it takes more than usual to warm up, t-stat is normally stuck open.
3. coolant temp sensor may be going south, and I think you should have 2 of those, one in t-stat housing and one in engine blosk.
4. check radiator for obstructions
5. was air bleeding done after t-stat replacement?

 

4. check radiator for obstructions as in glogged radiator fins, snow and ice stuck on it, dirt. whatever obstructs normal air flow through it.

 

Hi,

Thanks for the input. This problem started before I replaced the Tstat. I was driving today and when I noticed the gauge in about the 3 o'clock position, I decided to crank on my heat full blast. The temperature dropped down to normal operating temp in about 30 seconds and stayed that way as long as the heat remained on high. Any thoughts?

Regards, Brenden.

 

If the heater operation lowers the temp the coolant system is for some reason inadequate. The heater is acting as a small radiator.

Don't let the temp gauge go into the red or the head gasket can fail.

In a working Camry cooling system once the engine warms up and needle reaches mid range (typically just below this) the needle should stay fixed. It should not move if the engine has prolonged idle, hwy speeds, heater blower on or off, etc.

Find a thermometer such as cooking. Place this in the radiator fill port and let engine warm up. The fans should kick in around 199F.

Water temp sender should have an ohm reading of 160-240 ohm @ 122F and 17.1-21.2 ohm at 248F. You can approximate the ohm reading between there two temps.

Check all items listed by ukrkoz.

Sometimes flushing the radiator and block will help cooling (also flush the heater core).

On rare occasion the water pump impeller degrades causing overheating.

You should be able to full flow a garden hose into the radiator inlet port and have the water flow out the bottom port without backing up.

 

Greetings,

Well, I tried a few things and here are my results:

Since I have a new Tstat I drained the radiator and flushed it out top and bottom and cleaned off the radiator. Filled with coolant. Problem persists.

Disconnected wire at radiator and turned ignition to on. Fans started. Replaced the wiring harness. Took off radiator cap. Inserted digital meat thermometer in filler neck. Started engine. Took about 15 minutes to reach 195 degrees on thermometer. However, at this temp, the gauge was reading in the 3:30 position. By the time the fluid reached 197 to 198 the gauge was in the 3:00 position. Fans failed to turn on at 199. Discontinued test at 205 degrees with fans still not on, and dash gauge reading at the 2:30 position. Turned on AC and fans kicked in and heat gauge dropped to 4:00 position.

Any thoughts?

Regards, Brenden.

 

If the fans run when you disconnect the plug from the radiator and also when the AC is on check the radiator switch.

As you noticed the fans turned on with the switch was disconnected. This is opposite what one would expect. Take note the switch becomes ungrounded when the temp gets hot enough to operate the switch.

Check the dash gauge temp sensor ohm readings and determine if they vary too much with the small changes in coolant temp.

 

Hi,

Thanks for the reply. How do I check the radiator switch?

Regards, Brenden.

 

If you remove the switch and place the sensor end into heating water.

Should be no continuity when water temp is above 199F.

Should be continuity if water temp is below 181F.

 

Hi Joey,

Thanks for the input. Wouldn't it be safe to assume that this is the problem even without the test, considering that the fans fail to turn on even at 205 degrees? Is there anything else that would cause this other than the temp sensor?

Regards, Brenden.