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.
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
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.
Motorsforum.com is a website by car enthusiasts for car enthusiasts. It is not affiliated with any of the car or spare part manufacturers or car dealers discussed here.
All logos and trade names are the property of their respective owners.