K75S Cooling Question

QUICKDRAW · Apr 27, 2008

Lately there appears to be a single drop (maybe two) of coolent running down the reservor tank after every ride. I've drained and flushed the radiator, cooling fan appears to be working OK but no guess as to the reason for the escaping coolant. Anyone have a suggestion as to what to look for?

roy · Apr 28, 2008

Radiator cap? Hasit lost its seal so that coolant is forced out to easily and not drawn back in when the bike cools?

Just a guess

Roy

98lee · Apr 28, 2008

Cracked tank or cracked overflow hose from cap to tank?

:dance

tessler · Apr 28, 2008

I had a similar "leak" from a very worn rubber reservoir tank cover. Replaced it for $2.20 and have been "leak free" since.

motoedde · Apr 28, 2008

tessler said:
I had a similar "leak" from a very worn rubber reservoir tank cover. Replaced it for $2.20 and have been "leak free" since.

Quickdraw...Tessler has a good point. Depending on the age of your overflow bottle cap, which is different from the radiator cap; you might want to replace it. BMW actually changed the design on it and at $2.20...a cheap fix, and the most likely culprit.

The overflow line exits the radiator near the cap, and goes to the bottom of the overflow bottle. So if the drip is from the top of the overflow bottle, its probably the cap and not the overflow line/hose...

View the diagram on Max BMW's site for details...
http://www.maxbmwmotorcycles.com/fiche/MainDiagrams.asp?mospid=47908

HTH

LOSTBOY · Apr 29, 2008

K75s Cooling Question

On many K75s the battery cover (side panel) rubs the resevoir cover, either lifting it from it's seat or wearing a hole through it. You can fix this by filing a small bit of the cover off. The resevoirs occaisionally are roughly finished at the top. A bit of filing or sanding fixes this.

mrich12000 · Apr 29, 2008

Go to Fabric land, get a piece of velcro apply it to the new resevour..

QUICKDRAW · May 1, 2008

lostboy said:
On many K75s the battery cover (side panel) rubs the resevoir cover, either lifting it from it's seat or wearing a hole through it. You can fix this by filing a small bit of the cover off. The resevoirs occaisionally are roughly finished at the top. A bit of filing or sanding fixes this.

lostboy

Thanks, after looking at the side panel it does appear to rub against the reservor cap. I'll try a new cap and some sanding and see if the problem goes away. The cap itself is vented. Wonder if it could be a pressure problem as well?

jcridge · May 2, 2008

quickdraw said:
Lately there appears to be a single drop (maybe two) of coolent running down the reservor tank after every ride. I've drained and flushed the radiator, cooling fan appears to be working OK but no guess as to the reason for the escaping coolant. Anyone have a suggestion as to what to look for?

I had the same issue a few months ago with my K75 after replacing coolant. The reservoir level was set at 1/2 way up sight tube and radiator was topped up to just above the bottom of neck, air purged and good cap seal. I also had just a few drops for the first couple of trips, then it stopped. The reservoir never read above 1/2 when cool. I can only assume it was trapped air and a slight over fill causing coolant to push out during higher temperatures at high speed. If you find something different let us know.

K75S Cooling Question

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