Question about 2000 Mercury Grand Marquis

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Replaced engine coolant temperature sensor because of check engine light and overheating due to no fan operation. fan came on after change. However, now the temp display on the dash reads minimum always. fan is not coming on... Temperature displays on diagnostic tool display when plugged in... I swapped relays to rule that out when engine at 230 degrees.

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Make sure that your thermostat is working correctly. Let the engine warn up, not long enough for the vehicle to get into close loop, but to where the hose is warm. At this point the hose should be hard. If it isn't hard you will also hear the water flowing as you squeeze it. Often the thermostat goes into a fail safe mode which is all the way open and with the engine having run hot, this could have caused failure here. If it does't pass this test, it should be taken out and looked at. If it is bad you will see it all the way open...you can always compare it with the new one.

Posted on Mar 28, 2011

  • bobbyayo13ba May 18, 2012

    Check for sufficient water flow. Pull off bypass hose at water pump. Start for few seconds. Water flow will be immediate. If not diagnose water pump.

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Check if you have correct temp sensor. Computer is 2 wires, in German cars you see 4 wire applications.

Very important to inspect harness connector and pins for damage or corrosion. Sensor gives a resitance value to ecm for signal. Loose and corroded connectors will cause false readings.

Don't forget basics. Water flow, and thermostat operation.

And quite possible the parts department sold you a faulty one . Like that never happens.

To test sensor attach ohm meter and you should see a rise or fall of resistance reading with changing temperature. SiMply have a bowl of hot and cold water, dip Sensor back and forth in hot and cold water to see resistance change.

Posted on May 18, 2012

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Why is the temperature light keep coming on and the gauge keep going up and down?


Temperature Warning Light is on Inspection Service How this system works: With the exception of older, air-cooled vehicles, cars rely on a liquid called coolant (or antifreeze) to keep the engine at an optimal temperature. Coolant is a mixture of water and ethylene glycol, and it circulates around the engine block and absorbs excess heat, which keeps the engine from overheating. The coolant converts that heat to air in the radiator, and then the air is emitted, at which time the coolant is ready to absorb more heat. Without coolant, the engine would quickly ruin itself with its own heat production. Common reasons for this to happen:
  • Coolant is low or weak: The most common culprit when an engine overheats is low or weak coolant. If your car doesn't have enough coolant, then it can't absorb enough heat. While your car will naturally lose small amounts of coolant over the years, a leak is the most likely cause of low coolant levels.The proper ratio of coolant to water can also get distorted, resulting in a problem. Too little or even too much antifreeze can dramatically lower the boiling point of the coolant. A proper ratio of antifreeze to water is 50/50 to 60/40, depending on the vehicle.
  • Broken radiator fan shroud: The radiator fan shroud directs the airflow across the radiator so the air can absorb the coolant's heat. When the fan shroud breaks or becomes dislodged, air fails to enter the radiator, and the coolant will no longer have a place to direct the transfer of heat.
  • Broken or missing air dam: Along with the shroud, some vehicles have an air dam (or deflector) underneath the vehicle. If this is broken or missing then the air can pass underneath the vehicle but not also through the radiator, which will cause overheating. These air dams are essential in newer vehicles, as they force the air through the fan shroud.
  • Faulty coolant temperature sensor: The temperature sensor takes constant readings of the coolant temperature and sends that information to the engine control unit. Based on the temperature of the coolant, the engine control unit adjusts the ignition timing, the fuel injector pulse, and the operation of the electric cooling fan.
  • Bad water pump: The water pump is responsible for keeping the coolant cycling throughout the engine. After the coolant transfers its heat energy to the air, the water pump recirculates it around the engine so that it can absorb more heat. The most common water pump problems are a leaking pump, bad bearings, or an impeller that has rotted away due to a low coolant ratio.
  • Stuck thermostat: The thermostat acts as a dam for the coolant. When the engine first turns on, and it is still cold, the thermostat keeps the coolant from circulating, which allows the engine to warm up as quickly as possible. Once the engine has reached its operating temperature, the thermostat opens and allows the coolant to circulate. A stuck thermometer may stay permanently sealed and therefore keep the coolant from reaching the engine block.
  • The thermostat may also stick open. This will not usually result in overheating, but it will waste gas.
  • Broken engine cooling fan: The engine has a cooling fan that is deployed when the coolant needs some extra help. When the coolant temperature sensor notices that the coolant temperature is getting too high, the engine control unit (on newer vehicles) will initiate the cooling fan to reduce the temperature.
  • Broken thermostatic fan clutch: Older vehicles use a thermostatic fan clutch to engage the engine cooling fan, which is mounted to the fan blades. The fan clutch uses a bi-metallic spring that tightens when the temperature increases. This acts as a "high speed" option for the fan, and when engaged, it draws more air across the radiator.
  • Blown head gasket: The head gaskets sit between the engine block and the cylinder heads, and keep coolant from entering the engine's oil and combustion chamber. When a gasket blows and coolant seeps in, the issue is not only that the engine will overheat, but also that damage may be done to the catalytic converter and oxygen sensors due to contamination from the coolant. What to expect: A top-rated mobile mechanic will come to your home or office to determine the cause of the temperature warning light turning on and the source of the overheating, and will then provide a detailed inspection report that includes the scope and cost of the necessary repairs. How important is this service? An overheating engine is extremely dangerous. It is not safe to drive a vehicle with an overheating engine, or you may ruin the engine completely and put yourself at risk. As soon as you notice the light come on, pull over. If there is no place to safely pull over, turn off your radio and other electrical units, and turn your heat on high (this will funnel some of the hot engine air into the cabin). As soon as you can safely pull over, do so, and then book one of our mechanics to perform an inspection.

Sep 30, 2016 | 2008 Pontiac G6

3 Answers

Can either of these codes cause my 1999 Oldsmobile bravada SUV to over heat: P0442 ornP1361 or P0117??


code p 0442 refers to EVAP system so that is unlikely
check the fan operation and if you have a viscous fan hub ( fan clutch ) replace it
if you have electric fans , check coolant temperature sensor for operation , fuses , relay and fans
overheating is from low coolant levels , head gaskets/cracked heads, blocked radiator cores , fins flaking off core tubes, incorrect timing, blocked exhaust( cat converter)problem thermostat, over loading /over speeding, overdrive not engaging
if you over heating is predominately at lights , slow moving traffic or high engine rpms with low speed --check the fan operation and if it is viscous fan hub driven --replace the hub or if electric fans have that circuit checked out

Sep 07, 2016 | 1999 Oldsmobile Bravada

1 Answer

Overheating with AirCon ON, OK with Aircon OFF


if engine over heating coolant over flow jug will boil over you will see steam.sound like you have either faulty engine coolant temperature sensor or could have faulty fans relay or fuse or pcm problem if coolant fans dont turn on.have garage with code scanner that can do a snap shot on coolant temperature sensor check see how hot coolant temperature is see if coolant temperature over 220 degrees engine getting too hot.could have faulty water or blowed head gasket check engine oil on oil dip stick look milkly you have blowed head gasket. i use infra red laser thermometor check see how hot engine is over 107 celsius engine is overheating.

Dec 10, 2012 | 2000 Toyota Sienna

1 Answer

Overheating


OVERHEATING CAN BE CAUSE BY MANY THINGS LIKE FAULTY THERMOSTAT AND FAULTY RADIATOR PRESSURE CAP,TOO MUCH WATER IN COOLANT SYSTEM NEED 50 / 50 WATER AND ANTIFREEZE.LOOK FOR WATER PUMP WEEP HOLE LEAK, IF COOLANT LEAKING OUT WEEP HOLE WATER PUMP BAD NEED REPLACING.CHECK FOR LOW COOLANT LEVEL, YOUR RADIATOR OVERFLOW JUG SHOULD HAVE COOLANT AT THE FULL COLD MARK IF NOT KEEP ADDING COOLANT INTO COOLANT OVERFLOW JUG UNTIL COOLANT STOP DROPPING AND FULL COLD MARK, IF OVERFLOW COOLANT JUG WAS EMPTY RADIATOR IS LOW ON COOLANT.WHICH CAUSE AIR IN COOLANT SYSTEM KEEPING THE ENGINE COOLANT TEMPERATURE SENSOR FROM BEING SUBMERGE IN HOT COOLANT WHICH TURN ON THE COOLANT FANS.WHEN ENGINE COOLANT TEMPERATURE GET CERTAIN SET TEMPERATURE LIKE 190 DEGREES THE PCM AND COOLANT SENSOR WILL TURN ON COOLANT FANS, IF VECHICLE OVERHEATING COOLANT FANS NOT WORKING EITHER YOU HAVE FAULTY ENGINE COOLANT TEMPERATURE SENSOR CHECK COOLANT FANS FUSE AND RELAYS. YOU CAN CODE SCAN CAR TO SEE IF YOU HAVE FAULTY PCM, FAULTY ENGINE COOLANT TEMPERATURE SENSOR OR FAULTY COOLANT FAN RELAY.IF COOLANT FAN AND ENGINE COOLANT TEMPERATURE SENSOR OKAY,YOU HAVE CORRECT COOLANT LEVEL IN COOLANT SYSTEM, THERMOSTAT AND RADIATOR PRESSURE CAP BEEN REPLACED, YOU COULD HAVE BLOWN HEAD GASKET CHECK ENGINE OIL LOOKS LIKE MILK SHAKE HEAD GASKET BLOWED ALSO WHEN HEAD GASKET BLOWED YOU CAN DRIVE CAR SHORT DISTANCE START OVERHEATING AND YOU LOOSE ENGINE POWER SUSPECT BLOWED HEAD GASKET.

Aug 04, 2011 | 1999 Oldsmobile Alero

1 Answer

Crownvictorias2006 overheating all the time


Do you think that it's overheating because the temperature light is on? If so, then it's possible that you have a bad temperature sensor and not an overheating engine.
Look for other signs of engine overheating :
1. Sluggish engine operation.
2. Detonation upon acceleration (pinging).
3. Rough, uneven engine idle.
4. Coolant boiling in overflow tank.
If your vehicle is experiencing these symptoms, then overheating is indicated. One of the most common cases of overheating is a bad thermostat. Another common problem is a faulty cooling fan or fan circuit. The cooling fan can be checked by running the engine at operating temperature and turning on the AC control. if the fan does not come on, then a problem with the fan circuit is indicated. The thermostat can be checked by placing a cooking thermometer on the motor near the upper radiator hose where it attaches to the motor. the temperature should not go above 225deg. If it does, then replace the thermostat. If the temperature stays at or below this rating, then replace the temperature sensor. I hope that this information helps you with your problem and thank you for using Fixya.com.

WARNING : Be very careful when working around cooling systems when the engine is at operating temperature. DO NOT open the radiator cap (if equipped) or even the overflow tank cap when the system is hot. Always wear safety glasses. Remember that electric cooling fans can operate at any time, even after the engine is off. Keep hands away from fan when working in the engine compartment.

Jun 01, 2011 | 2006 Ford Crown Victoria

3 Answers

Took out the thermostat, replaced the radiator, the water is circulating in the radiator but it is still running hot. what do i do next?


Overheating can seriously damage a car's engine if left unchecked. Although overheating simply means that a car's engine temperature exceeds normal operating temperatures, the causes of overheating are varied. What follows is a brief list of some of the most common causes of engine overheating.

    Faulty Radiator
  1. A car that overheats will often have a faulty radiator. A radiator is responsible for cooling hot engine coolant that picks up heat from inside a car's running engine. A radiator "radiates" the heat from engine coolant out into the outside air. A faulty radiator loses its "radiating" effects and allows engine coolant to become overheated, thus rendering it ineffective at adequately cooling and engine.
  2. Faulty Water Pump
  3. A faulty or malfunctioning water pump prevents adequate engine coolant flow and can cause a car to overheat. A water pump serves to pressurize and propel engine coolant throughout a car's engine and radiator to increase the heat-reducing capabilities of engine coolant. A faulty water pump loses its ability to adequately pump and propel engine coolant, and can cause a car to overheat.
  4. Coolant System Leaks
  5. A leaky engine coolant system reduces the level of circulating engine coolant, which increases engine temperature and leads to engine overheating. Radiators, water pumps, and coolant system hoses and seals--all of these coolant system parts can develop leaks, which can result in low coolant levels and engine overheating.
  6. Faulty Thermostat
  7. A car thermostat regulates the flow of engine coolant. A thermostat is a heat-sensitive valve that opens when a car engine reaches a set operating temperature and closes when a car engine is cold and warming up. If a thermostat gets stuck in the closed position, coolant will be prevented from reaching the engine, which will quickly lead to engine overheating and potential engine damage.
  8. Low Engine Oil Level
  9. Engine oil, in addition to lubricating an engine's internal parts, helps to keep engine operating temperatures reduced by eliminating friction within the engine. If engine oil levels are low, friction and heat build up inside an engine, a condition that causes increased engine operating temperatures and can lead to engine overheating.

Jan 15, 2011 | 1998 Isuzu Rodeo

1 Answer

Hello... I got problem with my honda odyssey. For the past 3 days, if i start the engine, after 5 min the temperature will goes up to HOT and engine indicator light-up. I turn-off the engine and then start...


Your English is very good.

From what you have described, which is a rapid over heating of the radiator coolant fluid and therefore a hot engine condition, it would appear that the thermostat in the engine's cooling system is faulty.

If the thermostat is sticking in the closed or nearly closed position temporarily, there will be no flow or very little coolant flow between the engine and the radiator and the engine will overheat.

You have advised that after the engine is shut off , and radiator coolant fluid has cooled, you re-start the engine and drive the car without the overheating condition occurring again and the radiator coolant temperature is normal. This time there is no overheating because the thermostat is working normally.

You should have the thermostat replaced as soon as possible because allowing the engine to overheat can cause very expensive engine damage.

If you had a continuing overheating condition then I would suspect both the thermostat and the water pump. However as the overheating seems to be only temporary, and clears itself after you have shut down the engine and re-started it 10 minutes later (without further overheating arising) then I think you only have a faulty thermostat.

Please also check that the electric fans which draw air through the radiator are operating. These run on a temperature sensor and will switch on automatically once the radiator coolant fluid reaches a certain temperature and then switch off again when the fluid temperature reduces. You will hear them running once they start up. If these fans are not working the radiator coolant can quickly overheat in various driving and temperature conditions because there will be insufficient air flow through the radiator to cool the fluid. If the temperature sensor is faulty or has died, or if the electric motors running the fans are faulty, the fans will not operate.

I hope this helps.

Dec 18, 2010 | Honda Odyssey Cars & Trucks

2 Answers

I have a 91 Dodge Caravan LE 3.3 liter V6 engine, The long story on what problems I have had with this car is as follows. The first thing that happened was I had a fusable ling burn out on the van, this I...


For first check the coolant level.If its low then it must be made full.If its full then check out for any kind of coolant leak.If the coolant is low or getting leaked from somewhere then the car will overheat.So get the ac pressure test done.At any local car garage they do ac pressure test.Doing this test will let you know that there is coolant leak or not.If there is coolant leak then that leak is the cause of overheat.But if there is no coolant leak and coolant level is also full.Then ignore coolant cause for overheat.Then other cause may be the thermostat ,thermostat allows coolant to circulate when the engine is warmed up and should be closed when the engine is cold so that the car can warm up faster. It's a fairly inexpensive part that's replaced easily, but when it fails, your car can overheat, causing costly engine damage.
To check if thermostat is faulty try this procedure:--
Warm up the car but don't let it overheat--don't let the thermostat gauge go into the red.Turn off the engine.Open the hood.Find the upper radiator hose. It's black, is made of rubber and is about 2 inches in diameter, with metal clamps on either end. The upper hose goes into the top of the radiator.Locate the lower radiator hose. It looks similar to the upper hose except that it attaches to the bottom part of the radiator.Touch each hose very carefully (they can be extremely hot). If the temperature gauge is indicating that the engine is warmed up but one hose is hot and the other is cold, the thermostat is probably stuck closed, and the coolant isn't circulating through the radiator.the thermostat is faulty is the case. If the thermostat checks out ok then it can be faulty temp sensor.Its also called coolant temperature sensor. The coolant temperature sensor is a thermistor ( a resistor which varies the value of its voltage output in accordance with temperature changes. ). The change in the resistance values will directly affect the voltage signal from the water thermosensor. As the sensor temperature decreases, the resistance values will increase. As the sensor temperature increases, the resistance values will decrease.
The coolant temperature sensor lets the engine control computer know what the engine temperature is by gathering information from the engine coolant temperature.
There are several ways to know if the coolant temperature sensor is malfunctioning, if the sensor is bad it will trigger a trouble code and the check engine light in the dashboard will come on, you can retrieve the engine code and see if it is related to the coolant temperature sensor, even if the engine control computer doesn't store a trouble code, there is another way to suspect a bad coolant temperature sensor : If your vehicle starts using more fuel than usual, starts having trouble starting when the engine reaches normal operating temperature or you notice black smoke coming out from the exhaust tail pipe, it is very likely that these symptoms are related to a bad coolant temperature sensor. A thermostat that is stuck closed will cause the engine to overheat. To test if thermostat is stuck in the closed position, place the thermostat in boiling water. If the thermostat doesn’t open, than the thermostat is defective and needs to be replaced.
Check the Engine Coolant Fan
Since the cooling fan pushes air through the radiator to cool the coolant, a fan that’s not working properly will cause an overheat condition.
  1. Electric Fan – If the vehicle is equipped with an electric cooling fan, check to see if the fan is working properly. Most electric fans will only operate when the coolant temperature reaches a certain degree. In many vehicles when the air conditioner is turned on, the electric fan automatically turns on. The most common cause of an electric fan failure is the fan motor, a controller module or a relay.
  2. Engine Driven Fans – Some vehicle have cooling fan driven off the front of the engine. If the clutch (between the fan and the engine) is bad it may slip. If the clutch slips it may not allow enough rotation on the fan to be affective and the clutch needs to be replaced.
Thanks. Keep updated for any more query. You can rate this solution and show your appreciation.

Jul 21, 2010 | Dodge Caravan Cars & Trucks

1 Answer

1994 Camaro: My engine is overheating. Ive flushed the ratiator...


It could be the radiator fan motor if all sensors and relays have been changed.......unplug the coolant temperature sensor the fan should come on and stay on unless the motor is bad or it is not getting electrical current.

May 17, 2010 | 1994 Chevrolet Camaro

4 Answers

My engine is always overheating and we can not


CHANGE THERMOSTAT.MOST OF THE TIME THERMOSTAT WILL CAUSE OVERHEATING.CHECK YOUR COOLANT MAKE SURE ITS NOT LOW.HAVE COOLANT FANS CHECK TOO SEE IF THEY TURNING ON.GET A DIAGNOSTIC SCANNER HOOK UP TO CHECK FOR COOLANT TEMPERATURE SENSOR FAULT AND FAN RELAY AND FAN FAULT. MAKE SURE FAN FUSE IS GOOD.

Nov 12, 2009 | 2005 Pontiac Grand Prix

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