Sorry, having a total BLONDE moment (duh!). Of course brake fluid will expand if heated, same as ATFOriginally Posted by Spacenut
I rather foolishly assumed that because the brakes and clutch don't mysteriously jam on/de-clutch when hot that brake fluid was somehow immune from expansion. Of course it isn't; the expanding fluid merely moves into the fluid reservoir and the displaced air vents through the breather.
The hydraulic throttle has all the same features, but works rather differently - a bleed screw prevents the expanding fluid from entering the reservoir, which doesn't have a vent hole and is only filled with fluid when purging the system of air. So the only way for the expanding fluid to go is to force the pushrod out!
I'm such a dodo sometimes
Lauren