I checked the rad a few hours later and I had lost approx 250ml of fluid. So I topped back up.
On my return journey tonight, I started with the heater turned on and it stayed bang on normal all the way home, but zero traffic.
So my theory is by shutting off the heater valve it’s causing a build up of pressure, also there is white watery deposits on the front of the block, and in various parts, but I can’t see where they are coming from!
Thoughts?
Edited by beardylondon, 15 June 2019 - 10:23 PM.