I possibly have a pourous head on my 1991 Cav GSI. I read somewhere the sympton is a mayonnaise like substance in the coolant tank. Anyway yesterday i decided to drain the coolant system and engine of water so i could make sure it had the right amount of anti-freeze in it for the winter. Whilst i was doing this i noticed that all the water coming out was brown in colour. Is this a sign of a pourous head (i had the same thing on my 8V Astra GTE) or just bad water?
If it is a sign then can anyone give me some info on what it does, what needs to be fixed etc.
Thanks in advance.