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Playing with my 03GT the other day and noticed that with an ambient temp of around 90 degrees F. the fans alone can not reduce coolant temp enough to turn off the fans once they start. I have to ride the bike to get enough air across the radiator to shut the fans down.
Is that odd?
Every other water cooled bike I've had ........had fans and radiators large enough to cycle on and off even at 100 degree ambient. That's telling me the GT cooling system/fans are marginal. I've always thought the radiators were on the small side for a 1200.
What have you guys in the lower 48 states found?
 

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im in the northeast and on hot summer days they do seem to run a little hot but without knowing what the coolent temp really is its hard to say its at the point of over heating....are your radiators free of bugs and fod?..and your mix ratio?...could be just the sender saying its hottor than it really is....try blowing your fins out with compressed air and make sure that both fans are working and not just one...good luck!
 

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bluestreak said:
..with an ambient temp of around 90 degrees F. the fans alone can not reduce coolant temp enough to turn off the fans once they start. I have to ride the bike to get enough air across the radiator to shut the fans down.

[...]

What have you guys in the lower 48 states found?
Can't say with any certainty, as I have a difficult time discerning between when the fan is on or off because they seem to run pretty quiet. The droning of the engine and the use of a full-facer doesn't help. :D
 

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heat

Riding in Oklahoma summers will put any cooling systems to there test. I've found no problems at all Riding in 100 plus deg day's at hi speeds 80 + then pulling up to a stop. This will send the temp to clime high but the fans will pull it down quickly. If your having problems with this there could be several reasons. Is your coolant full check both your resovor and radiator. and if radiators are clear it could be a head gasket though Ive not herd of a problem there. also could be a bad ground to your temp sending unit. Lots of luck...
 

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Dealers comments re this

Hi, i asked my local BMW dealer about this too as the bike runs hotter (as stated by the temp guage) than other bikes i've ridden - they said that the KRS guage does show that it is running hot - i.e near the red area. I however have also noticed that when the fans come on it doesnt really bring the needle back down - only riding with air coming through reduces it.
I plan to change my coolant soon, as i dont know when it was done last - but i've also seen a mod that allows you to cut a hole in the front fairing to push more air onto the radiator (as it only has one air intake, the 'dummy' one can be cut out to do this mod).
Thanks
 

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I live in the desert. I have had no problem with engine heating at 110 degrees in stop and go traffic.
I over heated but not the bike.

I have seen that temp gauge in cool weather at high alltidute climb to the red zone. But the bike never over heated.

Make sure your radiators are clean.
 

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This is funny because the K75s had the opposite problem. My K75RT had a K100 radiator and the fan would only turn on at the extreme (stuck in traffic in hot weather.) Some owners who didn't have the benefit of stopped traffic would find that if they ever did need the fan, it would be stuck because it never runs.

But my '98 is not like that. When the needle climbs and fans kick on, it seems like it never comes down until I get going abut 45 mph or so, and then only after some distance. But it has never overheated, even riding in 90+ deg F weather, so I'm not concerned.

Recall also that these bikes have an oil cooler with no fan, so a portion of the cooling system is not working when you're not moving.

Early on I did have some coolant boil over (a few drops under the bike after stopping) that I fixed by replacing the radiator cap. The part number had been superceded so I figured it was probably a fault of the earlier design.
 
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