Anyone know proper temp range of factory coolant guage?

[bmw_jeff]

Based on my measurments and calculations I believe my temp sensor is sending the wrong info to my guage, since the sensor is a 12v part and my car is 6v. I won't bore you all with the V=I*R stuff but it seems it is making my guage read about 30-40F higher than the car really is, and gets disproportionally worse as the car gets hotter (which lowers the R of the sensor). This is what I found using a pyrometer:

At 1/2 or middle, just fully warmed up, the housing where the temp sensor is located reads about 173F. After lots of idling and reading slightly over 1/2 on the guage, I'm at about 180F. This seems normal I think?

Now, after some freeway driving in 80F+ temps, I will get up to the RED on the guage. When the needle is just entering RED, the housing is reading range of 193-203F in several tests. I would think it should not be reading RED until I get to 230F+ or more correct? Aftermarket guages seem to be 0-300F range, is this the same for BMW early temp guages? Anyone know or has tested their temp when its in the red? Interestingly my original owners manual states that you should "not be alarmed if the car runs into RED for short periods if it is under load or hot operating conditions". At what temp am I going to crack a head though, thats the question! Thanks!

[eastsidebimmer]

My 68 gets hot and it makes me nervous. I have a 70 c thermostat and I'm getting ready to install my new Curt I. radiator. Long freeway trips make my car run near the red too--people tell me to just keep driving, but I don't think it is safe to run so hot even with the heat on full blast. My radiator is unproven, so I'm replacing it. If I still run hot, then I'll know for sure. I do miss the mid way point "always safe" idiot gauge of my old E36.

[racebmw]

on the edge of the gauge face. If you looked at the very outside edge of the gauge there were numbers that showed the temperature of the end of the blue zone and the start of the red zone.

Don't have that car anymore or I would go look and tell you.

Jeff

[bmw_jeff]

I can read the 1st mark on the begining of the RED area of the guage at 105C = 221F. This confirms my theory that hte guage is reading too high, about 20F in this case. There is another number in the middle of the RED but I cannot make it out on my guage. Anyone have that number from thier pre-72 car? I'll search the archive or post another message, thanks for your help guys!

[Victor_PR]

(nt)