Overheating and coolant leak

Hi guys, Thursday night got home and the temp gauge was reading 107c. The fan was running and doing what it should. I parked the bike up as usual, and noticed that where I had shunted back and forth to turn round was a trail of coolant. Today (Sunday) I took the fairings off and expected to find a split hose, but nope, nothing. I removed the rad cap and found the rad was full of coolant. The only thing I found was the expansion was below minimum, and the vent tube that comes off the bottle just below the filler cap was wet with coolant at its end. I topped it up to the max mark and warmed the bike up. Got it up to 104c and nothing. The fan cut in as normal, and that's all. Except, the expansion tank filled up almost to capacity. I would assume that if the temp was a few degrees higher then it would have run out of the vent tube. Which I think is what happened Thursday night. I have a couple of questions though, should the rubber pipes be hard due to the coolant pressure? As mine were soft and you could squeeze them easily. Also should the expansion tank fill to such a high level when hot? Or is everything normal and I have no problem?

 

bad radiator cap not holding pressure.

 

And the upper mark on the tank is when up to normal operating temp. If you are filling it to max when cold, it will be too full when the rad dumps anything to it, possibly spitting some to the ground.

 

well I have the same problem... but saw this post after I created mine https://vfrworld.com/threads/coolant-leaks-from-reserve-tank-hose-at-higher-temperatures.56010/

 

Thanks for the replies, and thanks for the link. It does confirm my own thoughts, and today my new cap arrived. I will be fitting it asap and will post my results later.

 

New cap fitted, and it has sorted the problem. The water level is once again normal, and the pipes are now hard indicating pressure in the system. Thanks guys.

 

Yeah, I solved my problem with a new cap too
Now even the fan starts at lower temperatures and cooling is faster.