My temperature gauge is showing that my engine is running extremely hot. The radiator is full of water, the water pump seems to be functioning properly, because I can see waterflow through the radiator with the cap off, and after about a 45 minute drive this afternoon (in 90 degree heat), the radiator cap was pretty much cool to the touch.
The temp gauge won't drop below the red, and it does move when I rev the engine.
I'm sure my water temperature is not that hot. I know what an overheated engine does, and this engine is not running poorly and there is no coolant overflowing from the radiator.
Is there a sensor that feeds the temperature gauge? I need to know how to get started.
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Re: Dash Temp Gauge reading extremely hot
You need to pressure test the cooling system. If it holds pressure, I would look at replacing the water temp. sensor. If it doesn't hold pressure, you have a coolant leak going on. If you don't see it dripping on the ground or inside the car, I would be suspecting head gasket problem.
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Hi Bill, is the engine actually getting hot enough for the fans to come on? if the engine does have overheating problem (but you say the temp gauge reads normal) then i would check the operation of the engine temp switch, there are two, one for the gauge and one for the fans.
it could very well be a bad gauge. when it shows the engine to be overheated or at the least very hot, check the actual temp at the water outlet where the upper radiator hose attaches to the engine. use a non contact thermometer to check the temp so as not to get burned in the process. if the thermometer reads way different than the gauge, the gauge is bad.
This may be an electrical issue in the dash and a phantom problem. I would suggest measuring the water temperature in the radiator to see if it matches the guage (normal temperature should be around 90decC. Higher revs would increase water flow via the water pump not lower it so I am thinking some kind of restriction - check your radiator fins are not blocked there could be blockages in the radiator or less likely in the block valleys, other things to check are that your hoses are in good condition and they don't flatten with heat. A faulty thermostat is also possible.
Well the first question would be what does the temp gauge on the dash show after you have run the engine for 5 or 10 min ? If the gauge is in the middle of the temp range the engine is getting hot and either the heater core is stopped up or you have a problem with the blend door under the dash. If the temp gauge is staying around the cold mark the thermostat is not closing to warm up the engine. I am assuming the radiator is full of coolant.
The overheating could be a stuck thermostat, or a failed water pump among other things. If you are loosing coolant faster than the leak on the hose, you may be burning it out the exhaust pipe. Which would point to engine problems. If the temp gauge is not showing the engine is hot, and the fan is not coming on, what you are smelling may only be the drip blowing onto the exhaust pipe. The engine may not be running hot. A mechanic would use an infered thermometer or a scanner to "read" the engine temp to verify it is overheating. There is a chance the system is not actually full and has air pockets in it which would need to be bled out.
How do you know it gets hot? Are you going by the temperature gauge on the dash? Or have you checked under the hood and found out the engine really is running hot? ...Reason I ask is, something just doesn't sound right in your description. After just 5 minutes from starting and driving away, the engine would not yet be at normal operating temperature. That would explain the heater not yet warm. But the temp. gauge says hot? If so, I would replace the temperature sending unit on the engine. the one for the dash gauge, and see if that was the problem-not reading the temp. accurately. Couple of other things: Are you sure you got all the air out of the coolant system? Start the car with the radiator cap off and let it run until the engine is warmed up fully, then shut it off and install the cap. Does your reservoir tank stay about half full where it should be, between the full-hot and full-cold marks? If your problem persists. I would have the coolant system pressure tested, and see if you could get a true temperature reading of the coolant when it seems to be running hot. Good luck.
Did the engine overheat before the water pump was replaced? If so, you may have a warped cylinder head and/or blown head gasket.
Was the radiator full of rusty-colored liquid before you flushed it? If so, your radiator is probably restricted with rust deposits in the cooling tubes. Flushing WILL NOT get this stuff out. The radiator MUST be replaced if this is the case. Your heater core is probably not in real good shape either, so you should be expecting some heating problems this winter.
If the above is not the correct answer, then you should check to make sure the temperature gauge is not "LYING" to you. This could be caused by a defective gauge, a bad temperature sending unit, or faulty wiring.
The way to check this is with a scan tool that can read engine data and an infrared thermometer. While reading the coolant temperature data from the computer, check the cylinder head temperature with the infrared thermomometer. The readings you get should be within 5 degrees (F) of each other. If the computer data does not match the thermometer within the 5 degrees, then the sending unit for the computer should be replaced.
Then look at the gauge to see if the gauge reading is appropriate to the temperature readings that you took. Normal operating temperature is between 190 and 230 degrees. This should place the gauge at slightly to the right of center to about 5/8thsof the way to HOT. If the readings you took are OK and the gauge is reading higher than this, then you should try replacing the temperature sending unit for the gauge and see if that fixes the problem.
Please note that there are TWO temp sending units: One for the gauge and one for the computer.
If you are not getting a signal to your gauge, your car can still run. You just won't know if your car is overheating until it is too late. A bad thermostat won't keep your gauge from working. The temperature sensor that sends the signal to the gauge will keep it from working.
The thermostat helps your car in extreme weather. It helps your engine warm up in extreme cold so your heater will work sooner. And it helps you car cool itself off in extreme hot weather. As your engine water temp rises, the thermostat will open allowing the water in the radiator (that has been cooling) to flow into the engine block. The water that was in the block will go into the radiator to begin cooling.
If the gauge shows hot within the first 30 seconds of starting your car in the morning, you probably have an electrical short in your temperature sensor. This may be located on the engine block or on the radiator. If you can locate it, you might try to disconnect the electrical connector to it and see if the gauge stops indicating hot. If so, you might just buy and install a new temperature gauge sensor (you will need to drain the antifreeze from the radiator (and later replace/reuse it) using the finger-turned draincock at the bottom of the radiator, and should only do this when the engine is actually cold - check the temperature of the radiator cap and squeeze the radiator hoses to see that they are not pressurized, then if cold, remove the radiator cap, place a container below the drain and open the drain). Use teflon tape to wrap the threads of the sensor (in the opposite direction you would screw it in) before installing. Be aware that radiator fluid is toxic if injested by pets or people.