1 How do you know it is not running hot? Engines run normally at close to 90 deg. C, that is, close to the boiling point of water. The pressure cap on the radiator ensures that the water does not steam off at this temperature. 2 If the engine is not running hot and the gauge shows that it does, the gauge is faulty, probably the sender unit. I am not sure of the Buick, but some cars have two senders, one for the gauge on the dash and the other for the radiator fan. If your car has only one, the information from the sender is probably used by the ecu to switch on the fan, so if the sender is faulty you will get the symptoms you describe.
Check your fluids. Check the oil dipstick for signs of antifreeze mixing with the oil. It will look like milky brown sludge in the oil. Also check your coolant level. When the engine is cold, take off the radiator cap and check the level and color of the coolant. Also the overflow tank must have clean coolant up to the full cold mark.
Are you certain it is not running hot? Apparently the engine computer also thinks it is hot if the radiator fan has been turned on. If your fluids, oil and coolant, are at the full mark and are clear and not mixed, then it is possible that a bad coolant temperature sensor could be sending the wrong information.
The 3100 is known for intake manifold gasket failure after a lot of years and miles. This can cause internal coolant leaking into the oil, or sometimes into the cylinders, and then overheating from coolant loss, and further woes. If not caught in time, major engine damage can occur. Anytime you have low coolant level, find out where it was lost. You should never need to add coolant, its a closed system, sealed off from the outside, only slight evaporation loss through the overflow tank.
Answers & Comments
1 How do you know it is not running hot? Engines run normally at close to 90 deg. C, that is, close to the boiling point of water. The pressure cap on the radiator ensures that the water does not steam off at this temperature.
2 If the engine is not running hot and the gauge shows that it does, the gauge is faulty, probably the sender unit. I am not sure of the Buick, but some cars have two senders, one for the gauge on the dash and the other for the radiator fan. If your car has only one, the information from the sender is probably used by the ecu to switch on the fan, so if the sender is faulty you will get the symptoms you describe.
Check your fluids. Check the oil dipstick for signs of antifreeze mixing with the oil. It will look like milky brown sludge in the oil. Also check your coolant level. When the engine is cold, take off the radiator cap and check the level and color of the coolant. Also the overflow tank must have clean coolant up to the full cold mark.
Are you certain it is not running hot? Apparently the engine computer also thinks it is hot if the radiator fan has been turned on. If your fluids, oil and coolant, are at the full mark and are clear and not mixed, then it is possible that a bad coolant temperature sensor could be sending the wrong information.
The 3100 is known for intake manifold gasket failure after a lot of years and miles. This can cause internal coolant leaking into the oil, or sometimes into the cylinders, and then overheating from coolant loss, and further woes. If not caught in time, major engine damage can occur. Anytime you have low coolant level, find out where it was lost. You should never need to add coolant, its a closed system, sealed off from the outside, only slight evaporation loss through the overflow tank.