Hi all, after a bit of advice. Recently acquired a 2004 749 and noticed after every ride I'm loosing coolant from the small hole in the top of the expansion tank cap. I've fitted a new cap but problem still there. Any advise greatly appreciated.
Have you checked it's not over-full? The level is difficult to see. See post #16 here: https://www.ducatiforum.co.uk/threads/wot-no-light-switch.88101/#post-1887574
Thanks for replying, yeah checked the level with a torch, between the lines before setting off but obviously below after riding.
The main pressure of the coolant system should be managed by the cap fitted to the radiator and not the expansion bottle. if your getting excessive coolant coming out the expansion cap/overflow, the first port of call is the radiator cap to check its holding system pressure when the bike is at running temp. (is the bike overheating?) pull it out and check for seal damage, and also the spring is working before checking the fluid in the radiator. remeber that the cap is a PVRV ( Pressure vacuum regulation valve) so has 2 functions, control of pressure and allowing excess to pass to the expansion tank, and vacuum allowing fluid to return to the radiator as fluid temp drops and contracts. just pass your fingernail under the centre of the cap to lift the light spring of its seat to check for seal wear. if all is ok then check when the bike is running ( cold) with the radiator cap off and a light shining into the radiator, to see if there are any bubbles or a surge of fluid ( simple raise of level is ok due to pump operation) as this would indicate pressure is entering into the coolant system, ie. head gasket.
Brilliant, thanks for your reply. I'll give it a look later, hopefully it's just the cap and not gead gaskets! Cheers Chris.
If you need a new rad cap AS3 do a decent aftermarket replacement for less money than genuine Ducati. We run a higher pressure rad cap than standard on the Panigale on track to counter it being too quick to fill the expansion bottle. Not sure if it’s something you’d do on a 749 as I have no experience of them but might be worth looking into if you’re buying a new cap.
