my 1995 ford taurus has a intermitting engine knock when at idle and loses power when driving.also the heat stopped working it blows real cold now.the temp gauge read highwhen this first started,could someone tell me what the problem is .it has a 3.0

Lets just say i was gona buy a 1995 ford taurus for 0 that has an engine knock i know i should not buy it but lets just say i already did. Theres a slight knock that eases once the engine is warmed up and there is no white smoke. What can cause those knocks. actually its more like a tick.