Dear Colleagues,
My 907 started to leak coolant the other day…
Tracing back the leak I found it came from somewhere behind the radiator.
After disassembling the fairing and the radiator+fan I got to the faulty part: the aluminium tube where the 2 temperature sensors and the fan thermoswitch are placed.
In the picture you can hardly see but the green spot is the leaking point on the right side end (just where the hose connects to the tube).

Then I disassembled the tube to found a high degree of corrosion.
The SAMCO hoses and SAMCO wide clamps had done a good job holding the leak for a while until the coolant found its way.

Both temperature sensors and thermoswitch use aluminium washer but thermoswitch additionally had a suspicious pink product that I did not expect.
Is anybody familiar with this pink substance? I wonder if this is serial Ducati fitment or an amendment to prevent something.

maybe someone used sealant. Sometimes if used a very long time the coolant will leave some residue. Pink, blue, green depending on what colour the coolant has.
I`m wondering about all the black stuff on the sensors.

the pink stuff looks like dried Loctite gasket maker. You could probly fix that hole with a bit of epoxy steel or devcon , that's if its not corroded to bad , making a new one probly wouldn't be that bigger deal

looks like a perfect job for alumalloy

Thanks for your words and apologize for my slow reply (I only check the forum occasionally...).

One funny thing is that corrosion built from outside to inside of the tube (starting just were the hoses ends: there some very tinny coolant leak and air's oxigen met each other).

I got a NOS tube from Stein-Dinse and reassembled the 2 sensors and thermoswitch using mid strength threadlock LOCTITE (just in case). Particularly I was concerned about large thermoswitch thread as I feared high adequate tightening torque could bend the new tube.

As for the black substance... I suspect all internal galleries are covered in this. It looks like black paint hard flakes but it is like ash: when you touch with the tip of your fingers it melts like powder.

I washed the cooling circuit three times with distilled water and refilled with MOTUL MOTOCOOL FL (red). So far it runs fine.

Josep

It may be the pink is some kind of anti-seize as you say the tube is aluminum and the sensors are either steel or brass? There looks to be a crush washer for the sensors so torque value is probably low. I have had the tube out of my bike but could not break loose the sensors as I thought they were probably seized up and did not want to damage the tube.