After an uneventful drive to Dunsfold this weekend the level in my header tank dramatically changed, this was right after some hard use. The tank was completely full up so I thought I would leave it overnight before going any further. In the morning the cap had leaked slightly and when I released the cap there was a good cup full of coolant that came out.
I filled to the line then ran it last night, it appeared to be slightly warmer than usual but I put this down to paranoia. This am took it out for a last and all appears fine? Temp at 80 or on the 0 and no change in level.
Tomorrow I have booked Cadwell Park and am really unsure whether driving 300 miles + track time is going to be ok. Reading various things on here it seems that the first thing is an airlock somewhere, although it has been fine for the last 6 months since a rad change. Next the cap, could it be leaking? I don’t know what thermostat is in there and this morning the bottom hose was lukewarm after about 15 miles of driving. I don’t want to think HG as it seems unlikely and also an easy thing to say and overlook the obvious.
Opinions?