I have a cooling problem with my superduke 990.
The bike is a Superduke 990 from 2007 with 31000km on the clock.
Changed base gaskets and head bolts and valve cover gaskets 2500km ago.
Never changed water pump seal ring and shaft.
It started with a leak from some hoses and from the thermostat.
But all that is replaced now and it doesnt leak from that.
Then it started to leak fluid from the expansion tank, the hose behind the battery.
Like there is too much fluid in the system.
One ride the fluid levels where perfect, just above the cells in the radiator and between min and max in the expansion tank
But the next day when it has cooled down it had fluid in the radiator up to the radiator cap it was full and it had leaked on the floor under the bike.
Maybe it had sucked it from the expansion tank but it should not have been so much fluid in the radiator because it had leaked out some.
I replaced the radiator cap (did not solve the problem).
Then after a ride i saw that there was grey bubbles in the radiator and grey smudge under the radiator cap, so something is leaking oil into the cooling system.
Kinda looked like this, but more like a sludge.
The engine oil was replaced, oil looked like new and filter was like new.
It has been in the bike for 2000km.
So not a long time on the oil.
I run about 5000km on the oil.
Ive done a compression test, 14bar on both cylinders. Cold engine!
Then i replaced the coolant, i thought maybe it was mixed with different coolant types and there was oil in the cooling of the grey smudge so i wanted new fluid to see if there comes more oil/grey smudge bubbles.
This is what worries me is this sound!
I have a noise from the rear cylinder after the bike has warmed up, like a boiling sound.
Only from the rear cylinder.
The noise doesnt change if i open the radiator cap or the bleed screw on the waterpump.
Please listen on this youtube clip
https://youtu.be/LkAhMsZILfQ
Has anyone heard the noise or had the same problem that i have, what was the solution?
Well the problem with the overflowing didnt go away its not just a mixing of the coolants, its still there after the cooling change.
And i elevated the front tyre 50cm and bleed screws and so on.
I even ran the bike elevated with the cap open untill the thermostat opened.
I bought a new head gasket for the rear and a waterpump kit so i will change that.
But am i on the right track?
Best regards/ Fredrik Mehlin
