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Qube
12-22-2008, 07:56 AM
Alternator failed last week and was changed out. Water cooled so some draining and refill had to be done.

I've been watching the KTMP for a few days and it hovers around 105-108 highway driving (100kph or so) with ambients of -5 to -15.

Sound normal? It seems a little high to me. The idiot gauge points straight up. In stopped traffic, it may actually drop a few degrees but never under 100.

For those wondering how or what is KTMP... http://www.ideaphile.com/bmw/540-obc.html

According to that link, my temps aren't bad, but any other search comes up with people around the mid 90s. Go figure.

2002 540 E39...

Dado 540
12-22-2008, 12:17 PM
Hummm mine is around 98 degrees. The gauge only shows if the temperature is within the given range. Just for example if the KTMP is between lets say 90 and 110 the gauge will show that its in the dead center. If it goes over that range or below it will move. So you could still be running cold or hot and it wont show.

MLue1
12-22-2008, 12:38 PM
Alternator failed last week and was changed out. Water cooled so some draining and refill had to be done....Did they check the battery with a tester.... if not take it to Canadian Tire and have it tested other wise you maybe replacing another alternator real soon. E39s seem to kill batteries especially if there is some thing like a faulty ignition switch or FSU that is draining the battery.

Thanks for the link, I wasn't using that tool... nice to have it.

chromius
12-23-2008, 09:30 AM
Normal temp is 105 give or take a couple of degrees. So I would say you don't have anything to worry about. 108 might be a little high in -15 temps, but I wouldn't worry about it, since it's still well within specs.

If you're stuck in traffic for a long period of time you will notice the temp drop to around 85-90 degrees. This is how it's designed to work. The MAP controlled thermostat will automatically open up more if it senses you are in stop and go traffic in an attempt to bleed off heat; however, under normal circumstances it should stay at ~105 to maintain efficiency.