Hi...first post... I just bought a used 96 Camry with 185K miles ..drove home 100 miles no problem, the next day I drive to a friends and coolant dumps all over his driveway. You could hear gurgling in the engine (my friend said that the engine was EXTREMELY HOT but the gauge on the dash showed right in the middle (like everything was fine)...the coolant reserve was filled to top and had obviously overflowed. I replaced the thermostat and then had it checked at Car-x and they could not get it to overheat (although they didnt drive it)... I drove it home and sure enough it overflowed again (not as much) and again the gauge said middle.
I've read the service manual and they say to get guage put a 3.4w light bulb in place of the temp sensor but doesnt really explain how to test sensor (whereas other sensors it gives you curves of temp vs resistance)
1.any suggestions how to test that sensor
2.how can i measure what temp that sensor is seeing ?
3.that sensor only influences the guage, right ?
4.regardless, that is not the root of the problem, right ....any suggestions on how to debug ?

thanks in advance for ANY help.
Tim

 

so i have confirmed that the radiator temp switch is stuck open - causing the fans to run all the time...i've ordered a switch. This just causes fans to be on all the time but should not cause engine to overheat.

I found a light tester and hooked that from the temp guage wire to ground...the light lit up dimly and the guage went to half way...the manual says the gauge should go to hot... so...i'm still unsure if this was a good test ..they said to test with a 3.4w bulb, which if I calculate should have 280ma going through it (Power = 3.4w = 12v * .288a) but I only get 130ma....although i dont know how much voltage drop across gauge. Anyways does anyone have a better way of testing gauge or gauge sensor ?

I also found a digital meat thermometer that goes over 200 (tested it in boiling water)...so I want to see how hot the engine gets ..where would be the best spot to put this lead ?

Thanks
Tim

 

What engine model?

 

2.2L 4 cylinder model 5S-FE

 

more questions ..
1. checking out the radiator..... i was told to feel the radiator to see if it was evenly hot ..if one area was hot and others not it would suggest a blockage.... as I read the service manual it indicated that the radiator has 2 chambers - top for coolant and bottom for transmission ....so my question is HOW is the radiator partitioned ? If I wanted to feel for temp variation how far down can I check for even heating ?

2. Is there other tests I can do on the radiator to check operation ?

3. what tests can I do to test the water pump ? I read somewhere to squeeze the upper radiator hose and it should expand...not sure if I will be able to feel that ....is there better tests ?

 

A quick test of the fan coolant system is to unplug the wiring at the sensor on the radiator (ign switch on). The fans should start running. The system works opposite of what one would expect. When the relay connected to the switch is turned off (unpowered) the fans should run.

The switch should NOT have continuity if the coolant temp is above 199F and continuity below 181F.

The coolant system has 2 temp sensors. One is for the gauge, the other for the engine computer. The gauge sensor typically has just one wire going to it. The engine coolant sensor has 2 wires, one may be Brown, the other Green/Black.

Are you stating the coolant overflows but the engine is not overheating?

Any possibility of a blown head gasket. This can cause all kinds of strange overheating, coolant surging issues.

How is the radiator cap. It should pressurize the system to around 13psi (check cap for the number). If the spring in the cap is too weak, the coolant system will have less pressure boil at a lower temp.

The temp sensor for the gauge should have and ohm reading of 160-240 when the temp is 122F. 17.1-21.1 when the coolant temp is 248F.

I don't know what the light bulb test is. Assume this is a test of the gauge in the car. As you can see by the ohm readings above, the lower the reading the higher the gauge needle (hot).

One test of the gauge may be to ground the wire to the sensor (zero ohms), but this might damage the gauge due to excessive current flow (don't try this!!!). Hence the use of a light bulb. It has a very low ohm resistance but the filament can handle a lot of current. The bulb could simulate the sensor when the coolant is very, very hot!

Typically a bulb setup is used to test the fuel gauge without the tank sensor attached.

The trans cooler is build into the lower tank. The coolant flows around the trans cooler pipe. Rarely do they leak or cause other problems.

Feel the hoses after the engine has warmed up. The upper will be slightly higher in temp them the lower. The upper is the water outlet from the engine. If the radiator is plugged or coolant is not flowing through the radiator for other reasons, the upper hose may feel hot, the lower much colder. I have never found this test to work that well.

If you place a garden hose open to full flow into the upper radiator inlet, the water should flow out the bottom outlet without backing up. The coolant pump really circulates the water.

The water pump seldom fails. On rare occasion the blade may break loose from the shaft, or the fins become damaged but this is very rare.

Have you tried flushing the coolant system.

On this engine if the coolant fans are running the engine should never over heat at idle. If the fan system is working OK, the fans should turn on and off as the temp switch on the radiator opens and closes.

If you do think it could be a head gasket issue do what is called a block test. This tests the coolant for exhaust gases.

 

Wow...thanks for the wealth of information !!! This is unbelievable !!

Are you stating the coolant overflows but the engine is not overheating? it is overflowing and I THINK it is overheating. The overheating assessment is my friends- we could hear the fluid in the engine bubbling !!
The temp gauge at that point was in the middle which didnt make sense

Any possibility of a blown head gasket? I hope not as I asked at CAR-X if there was any serious issues before adding 4 new tires and they said it was fine....but to answer your question I dont know.

The trans cooler is build into the lower tank. The coolant flows around the trans cooler pipe. so would I expect even temp across the radiator? I got the engine warm, just idling in the garage ..the valve cover was at 144F, the exhaust manifold was at 204F and near the gauge sensor was 191, then turned off the engine. I then measured the temp at the radiator (fan side) at the top of the fan height it was 135, at middle of fan, 86 and at bottom of fan 81 ...is that normal or indicative of blockage ?

As far as flushing ....do I use Solder Seal/Gunk Radiator Flush (22 oz) and follow directions (i.e run engine,etc) or I bought some things to hook hose to do flush ?

I measured the resistance of gauge sensor ,it was 886 @ 72F, 70@150F and 47@191F ..I'm just guessing but it sounds in the ballpark compared to your numbers....or not?

I then tried a 33 ohm resistor in place of temp gauge sensor to ground and the guage only showed halfway...it seems that it should have moved higher. (if 17-21 is 248F) ? The problem is that I would have to take the whole dash off to fix, right ?

One other weird thing....I tried to measure the resistance of that sensor from the sensor pin to battery ground and I measured an open...I had to probe on the sensor case to get a reading (Instead of battery)...shouldnt it be a good connection from battery ground and case of sensor ?

The radiator cap said 0.9 on it ....you mentioned 13psi ...do I have the wrong cap or is the 0.9 mean something else ?

last, when I run the car in the garage (idling, the car does not overheat, which is what CAR-X did), however if the car is driven 10 miles or so and stopped is when it gets hot...(I need to take off the jacks and now that I have the thermometer measure how hot it gets after driving 10 miles.)

Thanks so much for help !!
Tim

 

Update:
1. I tried a 17ohm resistor from the temp guage wire to ground and the meter did go up to hot (so I think its working)

2. I bought a new radiator cap and when I took off the old one, they didnt look quiite the same...the old one did not have a piece of rubber in the middle. I put the new one on and drove the car and the overflow level did not rise at all !!!

the fans are still running all the time so I have to put the new switch on the radiator (tomorrow morning !)

after driving on the highway for 20 minutes,
the low hose (going to water pump) was cold (nothing flowing?)....the thermostat is supposed to open at 180 and I'm thinking that I didnt hit 180 degrees for it to open ....could this be a normal thing or does something sound wrong ?

Thanks again for any help !!

 

i replaced the radiator temp switch and now the fans don't instantly turn on
and after driving a while, it does not overheat, the radiator seems evenly heating and the low side hose is warm !!

now my only problem is that there is a leak of radiator fluid ...so will have to figure that out

now on to fix the RUST !

 

Good job in repairs.

Check the radiator upper and lower plastic tanks for small cracks and leaks. With age the tank can crack resulting in very small leaks. If you find leaks due to cracks replace the radiator as the cracks can get worse fast.

When the engine is cold, run you hand over all the coolant hoses, including the bypass hose that is harder to inspect plus the heater hoses, oil cooler hoses, etc.

Look at the bottom of the timing belt cover for signs of coolant leakage from the water pump.

The coolant overflow tank can break down with age and start leaking.