My 1.6 nb overheated a while back and after I replaced the old radiator it has continued to run pretty hot.
The coolant reservoir gets bubbles in it, smells like exhaust fumes, and gets discoloured very quick (turns brown and when it settles theres a brown layer at the bottom of the reservoir).
This made me think the head gasket was blown and the cylinders were leaking. I finally got around to compression testing the engine and the results seem fine, all cylinders are much the same, around 190 psi.
So now I have no idea whats causing the issues with the cooling system, has anyone else experienced anything similar?