328i Temperature Gauge Shows Hot Fast

I have a '97 328i with 116,000 miles. A few times the past month, the temperature gauge has quickly climbed from the normal dead-center position into the red when at idle. Either revving the engine or
getting the car moving would cause the needle to drop fast back to normal. This morning the gauge went into the red at 40 mph and then quickly dropped back down, so whatever the problem is, it's getting worse. I do not see any leaks or low coolant in the reservoir or radiator. Thanks for any help.
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Check the contacts on the back of the temp gauge they can go poor.Just clean and tighten them.This cured my same problem.
Mark

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usually when the temp gage moves erratically and quickly the problem is not engine temp related, but electrical in nature. check the connections on the back of the cluster. If no problem is found there then I would check the temp sensor. the temp sensor should not be too expensive if you dont find any connection problems. if that does not help then you may be looking at a problem with the cluster internally, of course if the engine is not really overheating. Good luck.
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hepcatal wrote:

Actually - NOT TRUE with modern BMW temp gauges. They are basically idiot lights done as a gauge. They indicate OK over a wide range of temps, and only go to the RED when something exceeds the temp.. but when they do - they go IMMEDIATELY into the red.
It sounds as if the OP has an airflow problem.. I'd suggest he check if his auxiliary fan (in front of the radiator) is coming on when the AC is turned on. If not - the fan is kaput (dead, nailed to the perch..) Not an uncommon failure actually.
IF that isn't the case - he also might want to check/replace his water pump.. the '97 date is right around when BMW phased them out due to failures.. and one that is starting to go can cause these symptoms as the impeller freewheels on the water pump drive shaft. In this case - if the system is open, I'd also do the thermostat.
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