I noticed that the coolant level drops when the engine is running (a Volvo D-20B) by about 2cms. Is this normal? I did have a small overheat a few months ago when the raw water had drained from the system, and a small amount of the FW coolant had escaped from the valve cap under pressure when it boiled briefly.
Yes, it's normal.
Many thanks, I will sleep better knowing that.
Neil