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My duke is loosing about 100ml of coolent about 1/2 inch on the viewing bottle after about an hour of riding and drops slightly more when sitting after a ride....
I've had the radiator pressure checked and the engine and gasket rebuilt trying to solve this... But after a test ride the coolent is still going somewhere but no one can figure out where... Has anybody had this problem b4. Or does anybody have any ideas on what could be the problem. Can't find a leak anywhere. Only drops after a ride....
Please help me its costing me a fortune and I can't ride it until I solve this but my best mechanics are scratching there heads
 

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Have you checked your oil? The two gaskets separating coolant from oil on the shaft of the water pump are known to let some coolant through in some cases.

In my case, the water pump shaft had damaged surface on it and was chewing through the gasket. Dealer replaced the gasket (by rebuilding the whole engine), and now everything is good.
 

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Varroa is right. There are two seals one on the inside and one outside on older Dukes, newer Dukes have three seals, one on the inside the engine, two outside (on the impeller side). If either one of these seal slow leaks, they won't show up as trouble, but eventually they go bust when riding full nuts some day. Start off by inspecting both the inner and outer seals and for peace of mind, I'd suggest replacing all the impeller seals.

Good luck.

Cheers!
VJ
 

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Varroa is right. There are two seals one on the inside and one outside on older Dukes, newer Dukes have three seals, one on the inside the engine, two outside (on the impeller side). If either one of these seal slow leaks, they won't show up as trouble, but eventually they go bust when riding full nuts some day. Start off by inspecting both the inner and outer seals and for peace of mind, I'd suggest replacing all the impeller seals.

Good luck.

Cheers!
VJ
To add to that, if any of the seals leak, there's a high chance of damage on the shaft, so if you're tearing down the engine, I'd strongly recommend replacing the shaft with OEM part, as well.
 
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