over heating led light on 91 16v er

[BigRon]

yeah, kicks in and spins a treat,
the temp gauge never seems to reach half way either, before i do the thermo i am going to by a new header tank lid.

[piggy]

I had a regular problem with my 8v temp light flashing and having to top up the watwer in the header tank every 500 miles.
I changed a few hoses and still had the problem. I was also thinking about changing the header tank but gave the system a good flush and then replaced the fluid.
The most important thing I did was make the mixture of water to antifreeze.
Now done over 1500 miles without it reoccuring.

[BigRon]

Do you think that its possible the incorrect mixture of ant ifreeze and water what could cause this...Also i have noticed that the top rad pipe seem to swell more than i thought. like a snake after a meal thin at both ends and fat in the middle.. any info on this please.