I purchased a '96 Camry a month ago that has developed overheating problems. I changed the radiator and thermostat and still had intermittent problems. A Toyota dealer diagnosed that the head gasket was beginning to fail so I had that replaced. The car was running fine for the past week until last night. It had been driven in stop and go traffic for about 45 minutes when the temperature gauge started to rise. When it reached about 3/4's up I pulled over and stopped so I could make sure the fans were operating. I watched the needle rise when the fans were running and fall when the fans stopped! I watched this happen for over 5 minutes. This is just the opposite of what happens in my Corolla. Could the fans be blowing in the wrong direction? Does anyone have suggestions for a solution? Many thanks!
It should be easy enough to determine which direction the fans are blowing by spraying a mist of water and seeing which way the mist blows. The fans should be blowing into the engine compartment and the fan shrouds should be in place.
Some other things to check:
The coolant should be translucent and be a 50-50 mix of anti-freeze and water. If it is not translucent or has a muddy appearance, the cooling system should be flushed and the coolant changed. If there is oil in the coolant, or if the engine oil looks like a milkshake, the head gasket may be leaking or the head may be cracked.
The radiator should be clean inside, and the outside should be free of debris. If the car has air conditioning, the outside of the condenser should also be free of debris.
When the cooling system was filled, the heater should have been set to full hot so that no air is trapped in the system as coolant is added, and the overflow bottle should also be filled.
The upper and lower radiator hoses should be pretty solid and not collapse when coolant is flowing.
When the thermostat was installed, the spring should be facing down.
Other things that can make a vehicle overheat are a restriction in the exhaust, inoperative EGR system, over-advanced ignition timing, slipping timing belt (not too likely), and incorrect spark plugs.
Make sure they used a Toyota Factory thermostat, and it's mounted the right way.
We hear wierd things about aftermarket thermostats - contrary to common sense, if you let the coolant flow too fast through the heads and cylinder jackets it can't pick up the heat properly. And the accelerated flow affects where the coolant swirls and eddies, and the flow doesn't go where the engineers intended it to.
The next thing before you get too involved tearing the whole car apart is to make sure that the dashboard temperature gauge isn't lying to you - it happens. It could be a bad gauge movement or engine mounted temperature sender, or a bad ground from the sender body threads to the intake manifold to the engine block.
You do NOT want to put 50 layers of Teflon Tape on the gauge sender or fan thermostat threads - The single-lead senders and switches count on making some metal-to-metal contact for the ground. This is where you use Rectorseal #5 pipe dope or the old black Permatex sealant instead of Teflon Tape. Same thing with gooping on Silicone Sealant and accidentally electrically insulating the water outlet adapter from the engine block.
You can get an aftermarket coolant temperature gauge and lash it up "temporarily" to see what is really going on.
You could have one or both electric cooling fan motors starting to go bad - they have bronze oilite bushings on the motor shafts, and they do wear out over time. And a symptom would be they run fine for a while, but when they get hot they'll start moaning or whining, the motor shaft heats up and they start seizing in the bore.
Check the ampere draw of each fan motor against the ratings, a bad motor can draw too little power (failing windings) or too much.
Also, get the radiator checked - with an Aluminum core and plastic crimped-on tanks they can't easily disassemble it like the old Copper jobbies, they can only chemically clean it out and do a flow test on the bench. If it fails the visual check or flow test, replace it.
The aluminum ones are cheap enough to be considered 'disposable', but if you will keep the car a while try to find an old-style Copper radiator. They can be unsoldered and rodded out every few years.
Remember the old Overheating Emergency tricks:
Trick One: Roll your windows down and turn the heater up all the way, full hot, full fan. That's adding some additional radiator surface to the system, but it dumps the heat in the car instead of under the hood.
Trick Two: Carry a 2-gallon garden sprayer, the pump-up kind, filled with clean water. If the engine is overheating, set the spray nozzle wide open and spray a heavy mist of water into the radiator. The evaporative cooling should drop the temperature like a rock.
And if the temperature still doesn't come down, you have other more complex problems. Collapsing or blocked radiator hoses (they can develop internal "aneurysms" of the liner layer that blocks the flow), corroded water pump impeller that is not moving the coolant, the water pump was rebuilt with a reverse rotation impeller from another car model...
In other words, never rule out stupidity at any stage. The parts man can hand you the wrong item even though it fits in the hole.
Use a thermometer to check the coolant temp as the engine warms up. The coolant fan should come on at 199F and turn off at 181F. See if the actual temp corresponds with the temperature gage position.
I am the original poster of this thread. I wanted to let everyone know the outcome of my "adventure". To make a long story short, I took the car back to the Toyota dealer who did the head gasket work. After three days of testing they gave me the car back saying they could not find anything wrong. Everything in the cooling system was operating as it should. I drove the car for less than a week and it started to overheat again. I happened to be on my way to the dealer for state inspection so the mechanic was able to see the car at the actual point of overheating. Still they couldn't find anything wrong! Finally the service technician suggested, as a last remedy, a power flush of the cooling system. The dealer didn't provide that service but recommended a nearby radiator shop. Eureka! The radiator shop owner said the radiator (which was only about a month old) was full of gunk! He was able to successfully flush out the radiator and the engine. I have been running for a week now and the temperature gauge needle sits comfortably just below the halfway point. I learned a lesson from this episode. If you are going to have a radiator replaced it's a good idea to have the entire cooling system flushed. Think of it as cooling system insurance; especially when buying a car from a private seller where the service history is unknown.
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