When i stop my engine after driving there are bubbles traveling up my water hoses into the header tank causing the water to temporarily rise and bubble. I do top the water up regularly. The previous owner said that regular top ups are to be expected. Is this the case or is that B*ll sh*t. I am worried that it is HG failure.
No mayonaise under oil cap.
Stage 3 saphire cossy.
Factory water hoses and radiator.Fans do come on regularly when the dial gets to the M of norm and cut out when the temp drops as they should do.

 

Bubbling is nothing to worry about, the coolant gets hotter after you switch off as the water pumps stops so the water absorbs the heat from the engine, this will be aggravated if the cap is a little dicky on the seal, and could also account for the water loss, but I would still check elsewhere, and the heater matrix/wet carpet ?
tabetha