But the expansion chamber, which is on the other side of the valve, is a sealed closed vessel, is it not ? Therefore what pressure the valve sees on the other side would only be dependent upon the temperature in the expansion chamber (and what has been forced into it) ? If the valve vents fluid into the expansion chamber when it gets hot is there a secondary, and therefore ultimate, safety valve that vents to atmosphere in the event of "excessive" overpressure ? I don't know.
Surely there has to be or the main rad cap valve couldn't function properly if pressure were over 1.2 bar both sides of the valve :/
Fair enough. Checked out my expansion tank filler and it does have a valve in it which appears to be pretty low pressure. I also ran my engine till the fans cut in and checked out the direction of flow. They suck.
Well if it is any consolation, I was out on my 1199 yesterday filtering down through traffic after a blast temp gauge got up to 100 very quickly, got to a set of lights and had to stop, temp went up very quickly, 101, 102, 103 at which point the fan must have came on as temp then started to drop & settled at 101 and remained so till I moved off. Lights are 3 way set which all operate individually I caught them as they changed to red so was sat there a fair while before they changed to green. Ambient air temp according to Panni's dash was 9 degrees c.
Catch tank is open to atmosphere but the overflow to it will feed into the bottom of the tank meaning that if it 'sucks' back it takes fluid back in to the expansion tank. At least that's how it is on the older (916 etc.) models.
"Catch tank is open to atmosphere but the overflow to it will feed into the bottom of the tank meaning that if it 'sucks' back it takes fluid back in to the expansion tank. At least that's how it is on the older (916 etc.) models." Dukedesmo seems to be describing fluid being sucked back into the expansion tank from a catch tank...
Yes, 916 models have the radiator, a pressurised header tank with a 'radiator' cap which overflows into an expansion tank which is vented to atmosphere. I believe later models may have done away with the (split-prone) header tank and have the radiator cap actually on the radiator, I would assume that the expansion tank is the same principle though?
999 has the rad cap on the radiator itself and you fill via the expansion tank which has a plastic cap with a small valve in it. The tank has a window with upper and lower water levels marked on it. This is on the inside, presumably so you can check the level without removing the fairing. Problem is I can't see the coolant level as a result and shining a torch in there doesn't seem to help. Anybody got any tips on this ??
Would it matter if was slightly over-full? I have a replacement alloy header tank on the 916 (after too many split tanks) and as such I can't see the level so I fill it to where I can see, i.e. the base of the neck which is likely to be over the 'recommended' level and then it just spits out the excess into the overflow tank.
I used a little artists paintbrush as a dipstick, so I do have some idea of the level. It does seem amazing though that Ducati would go to the trouble of providing a window complete with level markers if it is completely unusable, so I was wondering if there is some trick to it...
Haha! The window is perfectly visible but the level in it isn't because it's an opaque tank. Shining a torch at it doesn't seem to work. Maybe I could try sticking an led torch down into the top of the tank to light it up.
