on the way home tonight i look at the temp guage and noticed it was at the 3/4 point.....luckily i was almost home, i unscrewed the header cap (slowly and carefully) and a little cooland came out....about a teaspoon, after that the cooland level dropped down quite, should the header tank be full almost the top? and how full should the white plastic 1 be at the front of the engine?

thanks

 

it sounds like the rad has developed a leak and you have lost coolant. The header tank and rad should be full to the top. The plastic overflow bottle should operate between the two marks, max when hot, min when cold, that's about 1/4 to 1/2. The fact the OEM gauge move to 3/4 is bad news, the engine would have got really hot for it do that. The leak can be the finest of spray but there will be clues around the front of the engine bay.
I would establish normal level's and monitor very closely.
Trev