MDT

Does anyone know how many lines can disappear before the engine is starting to overheat? My car operates with three bars showing. If suddenly it went down to one bar, would it be overheating, and at what point would the idrive indicate an overheating problem? I have never had it happen thankfully, but have been curious as to the correlation between the bars and overheating.

Rudy

I really think it's a mistake to call these lines a "temperature gauge."

These lines, although tied to engine temperature, should not be used to judge the temperature like a true temperature gauge would allow. They are simply there to suggest the maximum rpm while the engine is coming up to normal operating temperature. Once it hits 3 bars (or 4, depending on engine) it is safe to rev the engine to it's normal red-line. (I can't say for sure but I'll bet that even when the car hits the 3 or 4 line mark, the car is still not to normal operating temperature.)

What the lines will not do is perform any indication of an overheating condition. Do not expect the lines to ever show anything less than the three or four lines that are there after a few minutes of running.

This is what you can expect if the engine becomes too hot:
http://forums.e60.net/index.php?showtopic=15555

It is unfortunate that we don't have a true temperature gauge or even a "vital statistics" screen in iDrive like many of us have wished for -- but that's an entirely different rant, I suppose...

http://forums.e60.net/index.php?showtopic=7220
http://forums.e60.net/index.php?showtopic=11412
http://forums.e60.net/index.php?showtopic=11269

///Marco.it

Strange, I've never seen mine below 5500. Considering also the outside temperature of abt. 23?C looks strange to me as I never had so low even at 0?C. Might be that the warning area changes by different engines your is an 8 cylinders and mine 6.

EBMCS03

Mines an 8. Whenever I start up the car it starts off at actually at 4500 RPMs and then those bars raise up really quick.

MDT

Rudy,

Thanks for the explanation and the links. I oftened wondered what to look for in an overheating condition. Now I know. My car needed coolant added at 12,000 miles, and I didn't know if I had a slow leak or if this was normal. I learned from this forum that this is normal (was at a year and a half time frame), but I still kept a close on it as I could swear I could smell a coolant smell when the car was warm. I haven't had any problem, so it was probably just my imagination.

ImolaRedM

A little off topic but the truth is most water temp guages in modern cars are so 'normalized' that they're almost useless (E39 included). They show cold-warm-hot but there is no real movement inbetween to give you a warning. Once it reads hot it's too late. The tachometer bars (if like the M5) is tied to oil temp. I would much rather have an oil temp guage than the more common water temp guage. I guess never really having the oil temp guage in a (non-M) 5er I'm okay with the loss of water temp. But I would like the option of having oil temp and oil pressure.