Thread: Z3 Roadster (E36/7) Running Temp
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Old 01-22-2013, 07:37 AM
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vintage42 vintage42 is offline
BMW CCA 1405
Location: Louisville, KY
Join Date: Jun 2007
Posts: 3,755
Mein Auto: 1997 BMW Z3 1.9 5MT
Originally Posted by BeemerMikeTX View Post
... You want your car to run at normal coolant temperature.
Therefore, you need to check to see if your "temperature gauge" is working properly (not sure how this is easily done; the BMW diagnostic computer?), and to double check the actual coolant temperature (external thermometer) and condition of the thermostat...
I think first it would be good to know what the normal full operating temperature. It is different for each car, for instance my 2006 Scion xB is 184 and my 2008 Forester is 192, as displayed by their ScanGauges. If he thinks his cooling system has a problem, and does not previously know his full operating temperature, a temperature reading has nothing for comparison.

I do think anything between 180 and 200 is probably normal full temperature for most cars. Not to be confused with the operating range. According to their ScanGauges, the Scion's blue light goes out at 139, and the Forester's needle reaches its steady point at 155. Both the light display and the needle display are moderated to remain steady and only cause alarm if the temperature is out of the wide operating range. The term "idiot" has been applied to this feature.

A quick rough check of coolant temperature can be done with a infrared thermometer gun.
Point its laser at the tank and the hoses. The temperature displayed will probably be lower than what the ECU is sensing internally, especially since the readings are on the other side of the thermostat.

If having a BMW dealer check the actual coolant temperature costs much money, one might consider buying a ScanGauge:
It shows the actual temperature sensed by the ECU, as well as about a dozen other operating parameters, plus reads codes and calculates mileage and range etc. It simply plugs into the OBD port (under the dash of most cars, or on the right side of the console in a Z3). Here's my Scion and Forester ScanGauges:
I only recently got the Z3 and will give it a ScanGauge once I figure out where to put it.
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